One of the important outcomes of this situation has been the recent rapid development of German lignite production, based on newly worked-out methods of treatment and utilization.

By taking over Alsace-Lorraine, France acquires about 70 per cent of the iron ore reserves and annual production of Germany. This production was in minor part smelted locally,—the larger part moving down the Rhine to the vicinity of the Ruhr coal fields, and Ruhr coal coming back for the smelting in Lorraine. This great channel of balanced exchange of commodities has been determined by nature, and is not likely to be permanently affected by political changes. For the time being, however, the drawing of a political boundary across this trade route hinders the full resumption of the trade. Self-interest will require both Germany and France to keep these routes open. France requires German coal to supply the local smelters near the iron fields, and German markets for the excess production of iron ore. On the other hand, Germany's great smelting district in the Ruhr Basin is largely dependent on the Lorraine iron ore, and the movement of this iron ore requires coal from down the Rhine as a balance.

The intelligent handling of this great coal and iron problem is of far-reaching consequence to the mineral industries of the world.

CONCLUSION

In the foregoing discussion it is not our purpose to argue for any specific national or international plan or procedure, but rather to show something of the nature of the problem,—and particularly to show that intelligent and broadened self-interest requires a definite national policy in regard to world mineral questions. Realization of this fact is a long step toward the solution of the international problems. No geologist, engineer, or business man is safe, in the normal conduct of his affairs, without some attention to these matters.

It is our purpose further to bring home the fact that international cooperation in the mineral field is not merely an academic possibility, but that in many important ways it is actually in existence. The terms of the Peace Treaty alone have far-reaching consequences to the explorer or mining man in all parts of the world. The modifications of these terms, which are inevitable in the future, will not be of less consequence. It is necessary not only to know what these are, but to aid in their intelligent formulation.

LITERATURE

A vast new literature on the subject of international mineral relations has sprung into existence during and following the war, and anyone may easily familiarize himself with the essentials of the situation. Some of the international features are noted in the discussion of mineral resources in this book. For fuller discussion, the reader is especially referred to the following sources:

The reports of the United States Geological Survey. Note especially World Atlas of Commercial Geology, 1921.

The reports of the United States Bureau of Mines.

Political and commercial geology, edited by J. E. Spurr, McGraw-Hill Book Co., New York, 1920.

Strategy of minerals, edited by George Otis Smith, D. Appleton and Co., New York, 1919.

Coal, iron and war, by E. C. Eckel, Henry Holt and Company, New York, 1920.

The iron and associated industries of Lorraine, the Sarre district, Luxemburg, and Belgium, by Alfred H. Brooks and Morris F. LaCroix, Bull. 703 U. S. Geological Survey, 1920.

The Lorraine iron field and the war, by Alfred H. Brooks, Eng. and Min. Journ., vol. 109, 1920, pp. 1065-1069.

Munitions Resources Commission of Canada, final report, 1920.

FOOTNOTES:

[58] Umpleby, Joseph B., Strategy of minerals—The position of the United States among the nations: D. Appleton and Co., New York, 1919, p. 286.

[59] Control is here used in a very general sense to cover activities ranging from regulation to management and ownership. The context will indicate in most cases that the word is used in the sense of regulation when referring to governmental relationships.



CHAPTER XIX

GEOLOGY AND WAR

GEOLOGY BEHIND THE FRONT

The experience of the great war disclosed many military applications of geology. The acquirement and mobilization of mineral resources for military purposes was a vital necessity. In view of the many references to this application of geology in other parts of this volume, we shall go into the subject in this chapter no further than to summarize some of the larger results.

As a consequence of the war-time breakdown in international commercial exchange, the actual and potential mineral reserves of nations were more intensively studied and appraised than ever before, with the view of making nations and belligerent groups self-sustaining. This work involved a comprehensive investigation of the requirements and uses for minerals, and thus led to a clearer understanding of the human relations of mineral resources. It required also, almost for the first time, a recognition of the nature and magnitude of international movements of minerals, of the underlying reasons for such movements, and of the vital inter-relation between domestic and foreign mineral production. The domestic mineral industries learned that market requirements are based on ascertainable factors and that they do not just happen. Large new mineral reserves were developed. Metallurgical practices were adapted to domestic supplies, thus adding to available resources. Better ways were found to use the products. Some of these developments ceased at the end of the war, but important advances had been made which were not lost. One of the advances of permanent value was the increased attention to better sampling and standardization of mineral products, as a means of competition with standardized foreign products. For instance, the organization of the Southern Graphite Association made it possible to guarantee much more uniform supplies from this field, and thereby to insure a broader and more stable market. Such movements allow the use of heterogeneous mineral supplies in a manner which is distinctly conservational, both in regard to mineral reserves and to the human energy factors involved. In another war the possibilities and methods of meeting requirements for war minerals will be better understood.

In these activities, geologists had a not inconsiderable part. The U. S. Bureau of Mines, the U. S. Geological Survey, state geological surveys, and many other technical organizations, public and private, turned their attention to these questions. One of the special developments was the organization by the Shipping Board of a geologic and engineering committee whose duty it was to study and recommend changes in the imports and exports of mineral commodities, with a view to releasing much-needed ship tonnage. This committee was also officially connected with the War Industries Board and the War Trade Board. It utilized the existing government and state mineral organizations in collecting its information. Over a million tons of mineral shipping not necessary for war purposes were eliminated. This work involved also a close study of the possibilities of domestic production to supply the deficiencies caused by reduction of foreign imports.

Other special geological committees were created for a variety of war purposes. In the early stages of the war a War Minerals Committee, made up of representatives of government and state organizations and of the American Institute of Mining Engineers, made an excellent preliminary survey of mineral conditions. A Joint Mineral Information Board[60] was created at Washington, composed of representatives of more than twenty government departments which were in one way or another concerned with minerals. It was surprising, even to those more or less familiar with the situation, to find how widely mineral questions ramified through government departments. For instance, the Department of Agriculture had men specially engaged in relation to mineral fertilizers and arsenic. Sulphur and other mineral supplies were occupying the attention of the War Department. Mica and other minerals received special attention from the Navy Department. The Tariff Board, the Federal Trade Commission, the Commerce Department, even the Department of State, had men who were specializing on certain mineral questions. All these departments had delegates on the Joint Mineral Information Board, in which connection they met weekly to exchange information for the purpose of getting better coordination and less duplication.

The National Academy of Sciences established a geologic committee, with representatives from the U. S. Geological Survey, the state geological surveys, the Geological Society of America, and other organizations. This committee did useful work in correlating geological activities, mainly outside of Washington, and in cooperation with the War Department kept in touch with the geologic work being done at the front.

While the activities of geologists for government, state, and private organizations were for the most part in relation to mineral resource questions, this was by no means the total contribution. The U. S. Geological Survey and other organizations, in cooperation with the War Department, did a large amount of topographic and geologic mapping of the eastern areas for coast-defense purposes. This work involved consideration of the topography for strategic purposes, as well as the stock-taking of mineral resources—including road materials and water supplies. The revision of Geological Survey folios, with these requirements in mind, brought results which should be of practical use in peace time. Studies were likewise made of cantonment areas, with reference to water supplies and to surface and sub-surface conditions.

Many geologists were engaged in the military camps at home and abroad, and in connection with the Student Army Training Corps at the universities, in teaching the elements of map making, map interpretation, water supply, rock and soil conditions in relation to trenching, and other phases of geology in their relation to military operations. The textbook on Military Geology,[61] prepared in cooperation by a dozen or more geologists for use in the courses of the Student Army Training Corps, is an admirable text on several phases of applied geology. The name of the book is perhaps now unfortunate, because most of it is quite as well adapted to peace conditions as to those of war. There is no textbook of applied geology which covers certain phases of the work in a more effective and modern way. The topics treated in this book are rocks, rock weathering, streams, lakes and swamps, water supply, land forms, map reading and map interpretation, and economic relations and economic uses of minerals. Another book,[62] on land forms in France, prepared from a physiographic standpoint, was a highly useful general survey of topographic features and was widely used by officers and others.

GEOLOGY AT THE FRONT[63]

Perhaps the most spectacular and the best known use of geology in the war was at and near the front. This use reached its earliest and highest development in the German army, but later was applied effectively by the British and British Colonial armies, and by the American Expeditionary Force.

One of the first intimations to the American public of the use of geology at the front appeared in the publication of German censorship rules in 1918,—when, among the prohibitions, there was one forbidding public reference to the use of earth sciences in military operations. A leading American paper noted this item and speculated at some length editorially as to what it meant.

It was discovered that geologists to the number of perhaps a hundred and fifty were used by the Germans to prepare and interpret maps of the front for the use of officers. Features represented on these maps included topography; the kinds of rocks and their distribution; their usefulness as road and cement materials; their adaptability for trench digging, and the kinds and shapes of trenches possible in the different rocks; the manner in which material thrown out in trenching would lie under weathering; the ground-water conditions, and particularly the depth below the surface of the water table at different times of the year and in different rocks and soils; the relation of the ground-water to possibilities of trench digging; water supplies for drinking purposes; the behavior of the rocks under explosives, and the resistance of the ground to shell-penetration; the underground geological conditions bearing on tunnelling and underground mines; and the electrical conductivity of rocks of different types, presumably in connection with sound-detection devices and groundings of electric circuits. Some of the captured German maps were models of applied geology. They contained condensed summaries of most of the features above named, together with appropriate sketches and sections. During the Argonne offensive by the American army the captured German lines disclosed geologic stations at frequent intervals, each with a full equipment of maps relating to that part of the front. From these stations schools of instruction had been conducted for the officers in the adjacent parts of the front.

The British efforts were along similar lines, although they came late in the war, under the leadership of an Australian geologist. Their efforts were especially useful in connection with the large amount of tunnelling and mining done on the British front. Among the many unexpected and special uses of geology might be cited the microscopical identification of raw materials used in the German cement. It became necessary for certain purposes to know where these came from. The microscope disclosed a certain volcanic rock known to be found in only one locality. In the Palestine campaign, the knowledge of sources of road material and water supply based on geologic data was an important element in the advance over this arid region. Wells were drilled and water pipes laid in accordance with prearranged plans.

In spite of the fact that the usefulness of geology had been clearly indicated by the experience of the German and British armies, the American Expeditionary Force was slow to avail itself in large measure of this tool; but after some delay a geologic service was started on somewhat similar lines under the efficient leadership of Lieutenant-Colonel Alfred H. Brooks, Director of the Division of Alaskan Resources in the U. S. Geological Survey. The work was organized in September, 1917, and during the succeeding ten months included only two officers and one clerk. For the last two months preceding the armistice there was an average of four geologic officers on the General Staff, in addition to geologists attached to engineering units engaged in road building and cement making, and plans had been approved for a considerable enlargement of the geologic force. The work was devoted to the collection and presentation of geologic data relating to (1) field works; (2) water supply; and (3) road material. Of these the first two received the most attention. Maps were prepared, based somewhat on the German model, for the French defenses of the Vosges and Lorraine sectors, and for the German defenses of the St. Mihiel, Pont-a-Mousson, and Vosges sectors. Water supply reports covered nearly 15,000 square kilometers. The following description of the formations, taken from the legend of one of the geologic maps, shows the nature of the data collected:

Silt, clay and mud, with some limestone gravel, usually more or less saturated, except during dry season (June to September), in many places subject to flooding. Surface usually soft except during Summer. These deposits are 1/2 to 2 meters thick in the small valleys, and 2 to 3 meters in the —— Valleys. Unfavorable to all field works on account of ground-water and floods, and not thick enough for cave shelters.

Silts with some clay and fine sands and locally some fine gravel and rock debris. These deposits occur principally on summits and slopes, and are probably from 1 to 2 meters thick. Even during dry season (June to September) they retain moisture and afford rather soft ground. In wet season the formation is very soft and often muddy. In many places water occurs along bottom of these deposits. Favorable for trenches, but which require complete revetment, and ample provision for drainage, not thick enough for cave shelters; cut and cover most practical type of shelter.

Clay at surface with clay shales below. This deposit occurs in flats and is usually saturated for a depth of 1 to 2-1/2 meters, during wet season, for most of the year the surface is soft, but in part dries out in Summer. Deep trenches usually impossible, and even shallow trenches likely to be filled with water; defensive works will be principally parapets revetted on both sides. Cave shelter construction usually impracticable, unless means be provided for sinking through saturated surface zone into the dry ground underneath. Cut and cover usually the most practical type of shelter in this formation.

Clay at surface with calcareous clay shale and some thin limestone layers below. This formation occurs in low rounded hills; surface saturated during wet weather, but terrain permits of natural drainage, and dries out during Summer; during wet season (October to May) the surface zone is more or less saturated, and ground may be muddy to a depth of a meter or more, ground-water level usually within two or three meters of surface. Trench construction easy, but requires complete revetment, and ample provision for surface drainage. Cave shelters can be constructed in this formation where the slope is sufficient to permit of drainage tunnels. The depth to ground-water level should always be determined by test shafts or bore holes in advance of dugout construction.

Surface formation usually clay 1 to 2 meters in depth; below this is soft clay shales or soft limestone. Surface usually fairly well drained, and fairly hard ground. In general, favorable for trenches and locally favorable for cave shelters. In some localities underground water prevents cave shelter construction. The presence or absence of underground water should always be determined by test shafts or bore holes in advance of dugout construction.

Surface formation consisting of weathered zone 1/2 to 1-1/2 meters thick, made up of clay with limestone fragments and broken rock. Below is compact limestone formation. The surface of this formation is usually fairly hard, and well drained except in wettest season. Trenches built in it require little revetting; very favorable for cave shelters, but requires hard rock excavation. Some thin beds of clay occur in some of the limestone, and at these a water bearing horizon will be found. Where a limestone formation rests on clay as near —— a line of springs or seepages is usually found. Such localities should be avoided, or the field works placed above the line of springs or seepages. This formation is best developed in the plateau west of ——. Here it is covered by only a thin layer of soil, hard rock being close to the surface.

The limestones afford the only rock within the quadrangle which can be used for road metal.

Quarries (in part abandoned).

Limestone gravel pits.

Locus of springs and seepages. These should be avoided as far as possible in the location of field works, especially of dugouts. Field works should be placed above the lines of springs.

The water supply maps with accompanying engineer field notes are models of concise description of water supply conditions, with specific directions for procedure under different conditions. A few paragraphs taken from these notes are as follows:

Ground overlying rock, such as limestone, compact sandstone, granites, etc., which are usually fractured, is from the standpoint of underground water, most favorable for siting of field works. Clay shales and clay hold both surface and underground water, and are, therefore, unfavorable for field works. The contact between hard rocks resting on clay or clay shales is almost invariably water bearing, and should be avoided in locating field works.

At localities where impervious formations (clay, etc.) occur at or near the surface, they hold the water and form a superficial zone of saturation. This condition makes trench construction and maintenance difficult, and cave shelters can usually only be made by providing means of sinking through the saturated zone. The surface saturated zone often dries out in summer.

In pervious, or almost pervious rocks, the zone of saturation, or ground-water level, lies at much lower depth, and may permit of the construction of field works as well as cave shelters above it.

Underground water bearing horizons and water bearing faults should be avoided in locating field works.

Wherever there is any uncertainty about the underground water conditions, test shafts or bore holes should always be made in advance of the construction of extensive deep works.

EFFECT OF THE WAR ON THE SCIENCE OF ECONOMIC GEOLOGY

In general, the war required an intensive application of geology along lines already pretty well established under peace conditions. Much was done to make the application more direct and effective, and a vast amount of geologic information was mobilized. The general result was a quickened appreciation of the possibilities of the use of geology for practical purposes. Perhaps the most important single result was a wider recognition of the real relations of mineral resources to human activities, and of the international phases of the problem. More specifically, there was a most careful stock-taking of mineral resources and a consideration of the "why" of their commercial use. Many new resources were found, as well as new ways to utilize them.

FOOTNOTES:

[60] Now known as Economic Liaison Committee.

[61] Military geology and topography, Herbert E. Gregory, Editor. Prepared and issued under the auspices of Division of Geology and Geography, National Research Council, Yale Univ. Press, New Haven, 1918.

[62] Davis, W. M., Handbook of Northern France, Harvard Univ. Press, Cambridge, 1918.

[63] For more detailed description of this subject the reader is referred to The use of geology on the Western Front, by Alfred H. Brooks, Prof. Paper 128-D, U. S. Geol. Survey, 1920.



CHAPTER XX

GEOLOGY AND ENGINEERING CONSTRUCTION

Economic applications of geology are by no means confined to mineral resources (including water and soils). The earth is used by the human race in many other ways. Human habitations and constructions rest on it and penetrate it. It is the basis for transportation, both by land and water. Its water powers are used. In these various relations the applications of geology are too numerous to classify, much less to describe. While only a few of these activities have in the past required the participation of geologists, the growing size of the operations and increasing efficiency in their planning and execution are multiplying the calls for geologic advice. The nature of such applications of geology may be briefly indicated.[64]

FOUNDATIONS

The foundations of modern structures such as heavy buildings, especially in untried localities, require much more careful consideration of the substrata than was necessary for lighter structures. In planning such foundations, it is necessary to know the kinds of rocks to be excavated, their supporting strength, their structures, the difficulties which are likely to be caused by water, and other geologic features. Failure to give proper attention to these factors has led to some disastrous results.

The planning of foundations and abutments of bridges requires similar geologic knowledge. In addition, there must be considered certain physiographic factors affecting the nature and variation of stream flow and the migration of shore lines.

SURFACE WATERS

Construction of great modern dams is preceded by a careful analysis of sub-surface conditions, in regard to both the rocks and the water. It is necessary to know the supporting strength of the rocks in relation to the weight of the dam; to know whether the rocks will allow leakage around or beneath the dam; and to know whether there are any zones of weakness in the rocks which will allow shearing of foundations under the weight of the dam in combination with the pressure of the ponded water. It is necessary to know whether the valley is a rock valley or whether it is partially filled with rock debris; if the latter, how deep this debris is, and its behavior under load and in a saturated condition. Here again physiographic factors are of vital importance, both in relation to the history of development of the valley, and to questions of stream flow and reservoir storage.[65]

Construction of dams is only an item in the long list of engineering activities related to surface waters. River and harbor improvements of a vast range likewise involve geologic factors. Problems of wave action, shore currents, shifting of shores, erosion, and sedimentation, which are of great importance in such operations, have long occupied the attention of the geologist. They belong especially in the branch of the science known as physiography.

Geology in relation to underground water supplies is discussed in Chapter V.

TUNNELS

The digging of tunnels for transportation purposes, for aqueducts, and for sewage disposal requires careful analysis of geologic conditions in regard to both the rocks and the underground water. Knowledge of these conditions is necessary in planning the work, in inviting bids, and in making bids. It is necessary during the progress of the work. Too often in the past disastrous consequences, both physical and financial, have resulted from lack of consideration of elemental geologic conditions.

The building of the great New York aqueducts and subways through highly complex crystalline rocks has been under the closest geological advice and supervision. The detailed study of the geology of Manhattan Island through a long series of years has resulted in an understanding of the rocks and their structures which has been of great practical use. In the aqueduct construction the kinds of rock to be encountered in the different sections, their water content, their hardness, their joints and faults, were all platted and planned for, and actual excavation proved the accuracy of the forecasts. An interesting phase of this work was the tunneling under the Hudson at points where the pre-glacial rock channel was buried to a depth of nearly a thousand feet by glacial and river deposits,—this work requiring a close study of the physiographic history of the river.

SLIDES

Slides of earth and rock materials, both of the creeping and sudden types, have often been regarded as acts of Providence,—but studies of the geologic factors have in many cases disclosed preventable causes. A considerable geologic literature has sprung up with reference to rock slides, which is of practical use in excavation work of many kinds.

The cause of such movements is gravity. The softer, unconsolidated rock materials yield of course more readily than the harder ones, but even strong rocks are often unable to withstand the pull of gravity. The relative weakness of rock masses on a large scale was graphically shown by Chamberlin and Salisbury,[66] in a calculation indicating that a mass of average hard rock a mile thick, domed to the curvature of the earth, can support a layer of only about ten feet of its own material. The structural geologist, through his study of folds, faults, and rock flowage, comes to regard rocks essentially as failing structures.

Disturbances of equilibrium, resulting in rock movements under gravity, may be caused by local loading, either natural or artificial. Natural loading may be due to unusual rainfall, or raising of water level, or increased barometric pressure. Artificial loading may come from construction of heavy buildings or dams. Movement may also result from excavation, which takes away lateral support—and such excavation again may be caused by natural processes of erosion or by artificial processes involved in construction. Movement may be caused by mere change in the moisture content of rocks, or by alterations of their mineral and chemical character, affecting their resistance to gravity. In still other cases, earthquakes are the initiating cause of movement.

In unconsolidated rocks, a frequent cause of movement is the presence of wet and slippery clay layers. The identification and draining of these clay layers may eliminate this cause. In certain sands, on the other hand, water may actually act as a cement and tend to increase the strength of the rock. Planes of weakness in the rock, such as bedding, joints, and cleavage, are also likely to localize movement.

Earth materials, and even fairly hard rocks, may creep under gravity at an astonishingly low angle. The angle from the horizontal at which loose material will stand on a horizontal base without sliding is called the angle of rest or repose. It is often between 30 deg. and 35 deg., but there is wide variation from this figure, depending on the shapes and sizes of the particles and on other conditions. It has been suggested that even the slight differences in elevation of continents and sea bottoms may, during long geologic eras, have caused a creep of continental masses in a seaward direction.

In problems relating to slides, the geologist is concerned in determining the kinds of rocks, their space relations, their structures and textures, their metamorphic changes, their water content and the nature of the water movement, their strength, both under tension and compression, and other factors.

In the digging of the Panama Canal, a geological staff was employed in the study of the rock and earth formations to be met. However, had more attention been paid to geologic questions in the planning stages, this great undertaking, so thoroughly worked out from a purely engineering standpoint, would have avoided certain mistakes due to lack of understanding of the geological conditions. It is a curious fact that in these early stages no strength tests of rocks were made, and that no thorough detailed study was made of the geologic factors affecting slides and their prevention. It was only after the slides had become serious that the geological aspects of the subject were intensively considered. The results of the geologic study, therefore, are useful only for preventive measures for the future and for other undertakings. One of the interesting features of this investigation was the discovery that certain soft rock formations were rendered weaker rather than stronger by the draining off of the water. It had been more or less assumed that the water had acted as a lubricant rather than as a cement.

SUBSIDENCE

Not the least important application of geology to slides is in relation to deep mining operations. While the mining geologist has been principally engaged in exploration and development of ores, he is now beginning to be called in to interpret the great earth movements caused by the sinking of the ground over mining openings. For instance, the long-wall method of coal mining has resulted in a slow progressive subsidence of the overlying rock, affecting overlying mineral beds and surface structures over great areas. Detailed studies have been made of this movement, in order to ascertain its relation to the strength and structure of the rocks, its relation to the nature of the excavation, its speed of transmission, and the possible methods of prevention. German scientists have perhaps gone further with this kind of study than anyone else. In an elaborate investigation of subsidence over a coal mine in Illinois,[67] unusually complete data were obtained as to the nature, direction, and speed of the transmission of strains through large rock masses, and as to their effect in producing secondary rock structures.

RAILWAY BUILDING

In railway building, the planning and estimation of cuts and fills is now receiving geologic consideration, in order to make sure that no geologic condition has been overlooked which will affect costs, the stability of the road, or the accurate formulation of contracts. The location of best sources of supply for ballast is also a geologic problem (see pp. 90-91).

The physiographic phases of geology also are finding important applications to railroad building. The physiographer studies the surface forms with a trained eye, which sees them not as lawless or heterogeneous units but as parts of a topographic system, and he is able to eliminate much unnecessary work in the location of trial routes. Further study of some of the older railroads from this standpoint has led to considerable improvements. Physiographic study has also been applied to railway bridge construction, in the appraisal of the difficulties in surmounting stream barriers. A still broader use of physiography or geography, not popularly understood, is illustrated in the case of certain transcontinental railroads, in the study of the probable future development of the territory to be served—many features of which can be predicted with some accuracy from a study of the rocks, soils, topography, conditions of transportation, and natural conditions favoring localization of cities. The location of new towns in some cases has been based on this kind of preliminary study.

In locating an Alaskan railway close to the end of a momentarily quiescent glacier, troubles were not long in appearing, due to the fact that the glacier was really not as stable as it seemed to the layman. A specialist on glaciers, knowing their behavior, their relations to precipitation, their relations to earthquakes, the speed of their movement, and the periodicity of their movement, was ultimately called into consultation on the location of the railroad.

ROAD BUILDING

Road building in recent years has become a stupendous engineering undertaking, which is requiring geologic aid to locate nearby sources of supply for road materials. A considerable number of geologists are now devoting their attention to this work. It relates not only to the hard-rock geology but to the gravel and surface geology. Certain northern states are using specialists in glacial geology to aid in locating proper supplies of sand and gravel.

GEOLOGY IN ENGINEERING COURSES

Many engineering courses include elementary geologic studies, in recognition of the close relationship between geology and engineering. Men so trained, though not geologists, have been responsible for many applications of geology to engineering. With the increasing size and importance of operations, calling for more specialization, the professional geologist is now being called in to a larger extent than formerly. A logical trend also is the acquirement of more engineering training on the part of the geologist, for the purpose of pursuing these applications of his science.

FOOTNOTES:

[64] Excellent texts on this subject may be found in Military Geology and Topography, Herbert E. Gregory, Editor, prepared and issued under the auspices of Division of Geology and Geography, National Research Council, Yale Univ. Press, New Haven, 1918, and Engineering Geology, by H. Ries and T. L. Watson, Wiley and Sons, New York, 2d ed., 1915.

[65] Atwood, W. W., Relation of landslides and glacial deposits to reservoir sites in the San Juan mountains, Colorado: Bull. 685, U. S. Geol. Survey, 1918.

[66] Chamberlin, T. C., and Salisbury, R. D., Geology, vol. 1, 1904, pp. 555-556.

[67] Schultz, Robert S., Jr., Bull. Am. Inst. Mining and Metallurgical Engrs. In preparation.



CHAPTER XXI

THE TRAINING, OPPORTUNITIES, AND ETHICS OF THE ECONOMIC GEOLOGIST

Economic geology is now an established and well-recognized profession, but there is yet nothing approaching a standardized course of study leading to a degree in economic geology. There are as many different kinds of training as there are institutions in which geology is taught. Within an institution, also, it is seldom that any two persons take exactly the same groups of geologic studies. This situation allows wide latitude of training to meet ever changing requirements, but in other respects it is not so desirable.

PURE VERSUS APPLIED SCIENCE

In no institution are all the applied branches of geology taught. There is constant pressure for the introduction of more applied courses; this seems to be the tendency of the times. The economic geologist, fresh from vivid experiences in his special field, is often insistent that a new course be introduced to cover his particular specialty. Any attempt, however, to put into a college course a considerable fraction of the applied phases of geology would mean the crowding out of more essential basic studies. To yield wholly to such pressure would in fact soon develop an impossible situation; for, on the basis of time alone, it would be quite impossible to give courses on all of the applied subjects in a training period of reasonable length.

On the other hand, the failure to introduce a fair proportion of applied geology, on the ground that the function of the college is to teach pure science and that in some way economic applications are non-scientific, seems to the writer an equally objectionable procedure,—because it does not take into account the unavoidable human relations of the science, which vivify and give point and direction to scientific work. The development of science in economic directions does not necessarily mean incursion into less scientific or non-scientific fields. It is true that many of the economic applications of geology are so new and so constantly changing that they are not yet fully organized on a scientific basis; but this fact is merely an indication of the lag of science, and not of the absence of possibilities of developing science in such directions. There is today a considerable tendency among geologists of an academic type, whose lives have been spent in purely scientific investigation and teaching, to assume that anything different from the field of their activities is in some manner non-scientific, and therefore less worthy. Many economic geologists have been made to feel this criticism, even though seldom expressed openly. For the good of geologic science, this tendency seems to the writer extremely unfortunate. The young man entering the field of economic geology should be made to understand that his is the highest scientific opportunity; and that if parts of his field are not yet fully organized, the greater is his own opportunity to participate in the constructive work to be done.

Under war requirements many geologists were called upon to extend their efforts to bordering fields of endeavor. In some quarters these activities were regarded as non-scientific, and as subtracting from efficiency in purely geological work,—and yet out of this combined effort came a wider comprehension of new scientific fields, between the established sciences and between sciences and human needs. It is inevitable that in the future these fields, now imperfectly charted, will be occupied and developed, perhaps not by the men who are already well established in their particular fields of endeavor, but by coming scientists. In this light, it was a privilege for geologists to participate in the discovery and charting activities of the war.

Still another attempt to discriminate between scientific and non-scientific phases of geologic effort has been the assumption by certain scientific organizations with reference to standards of admission,—that work done for practical purposes may be regarded as scientific only if it leads to advancement of the science through the publication of the results. There is by no means any general agreement as to the validity of this distinction. On this basis, some of the most effective scientific work which is translated directly into use for the benefit of civilization is ruled out as science, because it is expressed on a typewritten rather than on a printed page.

While applied phases of the geologist's work may be truly scientific in the broader sense, it is undoubtedly easy in this field to drift into empirical methods, and to emphasize facility and skill at the expense of original scientific thought. The practice of geology then becomes an art rather than a science. This remark is pertinent also to much of non-applied geologic work in recent years. A considerable proportion of this empirical facility is desirable and necessary in the routine collection of data and in their description; but where, as is often the case, the geologist's absorption in such work minimizes the use of his constructive faculties, it does not aid greatly in the advancement of science.

Geology is by no means the only science in which there has been controversy as to the relative merits of the so-called pure and applied phases; but as one of the youngest sciences, which heretofore has been pursued mainly from the standpoint of "pure science," it is now, perhaps more than any other science, in the transition stage to a wider viewpoint. In the past there was doubt about the extension of chemistry toward the fields of physics and engineering, and of physics toward the fields of chemistry and engineering, and of both physics and chemistry toward purely economic applications; but out of these fields have grown the great sciences of physical chemistry, chemical engineering, and others,—and few would be rash enough to attempt to draw a line between the pure and applied science, or between the scientific and non-scientific phases of this work. This general tendency means a broadening of science and not its deterioration.

COURSE OF STUDY SUGGESTED

There are almost as many opinions on desirable training for economic geology as there are geologists, and the writer's view cannot be taken as representing any widely accepted standard. On the basis of his own experience, however, both in teaching and in field practice, he would lay emphasis on the fundamental branches both of geology and of the allied sciences,—general geology, stratigraphy, paleontology, physiography, sedimentation, mineralogy, petrology, structural and metamorphic geology, physics, chemistry, mathematics, and biology. After these are covered, as much attention should be given to economic applications as time permits. The time allowance for training, at a maximum, is not sufficient to cover both pure and applied science. Subsequent experience will supply the deficiencies in applied knowledge, but will not make up for lack of study of basic principles.

It is safe advice to a student wishing to prepare for economic geology that there is no royal road to success; that his best chance lies in the effort to make himself a scientist, even though he cover only a narrow field; that if he is successful in this, opportunities for economic applications will almost inevitably follow. To devote attention from the start merely to practical and commercial features, rather than to scientific principles, brings the student at once into competition with mining engineers, business men, accountants, and others, who are often able to handle the purely empirical features of an economic or practical kind better than the geologist. In the long run the economic geologist succeeds because he knows the fundamentals of his science, and not because he has mere facility in the empirical economic phases of his work. Of course there are exceptions to this statement,—there are men with a highly developed business sense who are successful in spite of inadequate scientific training, but such success should be regarded as a business and not a professional success.

Geology is sometimes described as the application of other sciences to the earth. This statement might be made even broader, and geology described as the application of all knowledge to the earth. In the writer's experience, the best results on the whole have been obtained from students who, before entering geology, have had a broad general education or have followed intensively some other line of study. Whether this study has been the ancient languages, law, engineering, economics, or other sciences, the results have usually been good if the early training has been sound. To start in geology without some such background, and without the resulting power of a well-trained mind, is to start with a handicap in the long race to the highest professional success. It follows, then, that intensive study of geology should in most cases not begin until late in the undergraduate course, and preferably not until the graduate years. Two or three years of graduate work may then suffice to launch the geologist on his career, but so great is the field, and so rapid the growth of knowledge within it, that there is no termination to his study. It is not enough to settle back comfortably on empirical practice based solely on previously acquired knowledge. Each problem develops new scientific aspects. It is this ever renewing interest which is one of the great charms of the science.

However, whether the student has a general training in geology, a specialized knowledge of certain branches, or takes it up incidentally in connection with engineering and other sciences, he will find opportunities for economic applications. The frequent success of the mining engineer in the geological phases of his work is an indication that even a comparatively small amount of geological knowledge is useful.

The writer is inclined to emphasize also the desirability of what might be called the quantitative approach to the subject,—that is, of training in mathematics and laboratory practice, which gives the student facility in treating geologic problems concretely and in quantitative terms. Geology is passing from the descriptive and qualitative stages to a more precise basis. For this reason the combination of geology with engineering often proves a desirable one. It is not uncommon for the student trained solely in the humanities and other non-quantitative subjects to have difficulty in acquiring habits of mind which lead to sufficient precision in the application of his science. He may have a good grasp of general principles and be able to express himself well, but he is handicapped in securing definite results. This does not necessarily mean that a large amount of time should be given to study of quantitative methods; exact habit of mind is more important in the early stages than expert facility with methods.

The teacher of economic geology finds his data so voluminous that it is difficult to present all the essential facts and yet leave sufficient time for discussion of general principles or for drill in their constructive application. It is difficult to lay down any rule as a guide to the proper division of effort; but from the writer's point of view, it is a mistake to attempt to crowd into a course too many facts. At best they cannot all be given; and in the attempt to do so, the student is brought into a passive and receptive attitude, requiring maximum use of his memory and minimum use of his reasoning power. Presentation of a few fundamental facts, combined with vigorous discussion tending to develop the student's ability to use these facts, and particularly tending to develop a constructive habit of investigation, seems to be the most profitable use of time during the course of training. The acquirement of facts and details will come fast enough in actual practice.

The variety, amount, and complexity of the data available in geology tend in themselves toward generalizations in teaching—toward the deductive rather than the inductive method. A certain amount of generalization is desirable, but its over-emphasis develops bad habits of mind on the part of the student, and requires radical readjustment of his ideas in subsequent field investigations. To retain a proper emphasis on inductive methods, it is necessary to limit the amount of data presented. Good results have been obtained by using the "case system," now common in the teaching of law—that is, by starting with a specific fact or situation as a basis for developing principles.

Another advantage in the restriction of data is the opportunity thus afforded for spending more time in the study of original reports rather than of the short textbook summaries. The student thus learns where the best primary sources of information are, how to find them, and how to extract essentials from them.

FIELD WORK

Field work is an essential part of any course of geologic training. Not only should it be taken at every opportunity during the regular school year, but no summer should be allowed to pass without geologic practice in the field. Opportunities for such work are offered in the summer field courses given by various institutions. In recent years it has usually been possible, also, for the student with elementary training to take part in summer geological survey work for state, national, or private organizations. In fact, after two or three years of geologic training, it is comparatively easy for the student to earn at such intervals during the year a fair fraction of his year's expenses.

The ideal arrangement, from the writer's viewpoint, would be about an equal division of time between indoor and outdoor study. The alternation from one to the other supplies a much needed corrective to clear thinking. It is impossible to bring all the subject materials into the classroom and laboratory; such study must inevitably be more or less deductive and generalized. If the student at frequent intervals is not able to acquire and renew a mental picture of field conditions, there is likely to be a faulty perspective even in regard to principles, and a considerable gap between the theoretical and applied phases of his knowledge. It may be possible in the classroom, for instance, to discuss faults in great detail with the aid of maps, diagrams, and pictures; and yet it is extremely difficult to get a real three-dimensional conception of the problems without actually standing on the ground.

SPECIALIZATION IN STUDIES

With the increasing size and efficiency of human operations has come an inevitable tendency to specialization. Where, in the past, the necessary geologic work might be passably done by the mining engineer, the local superintendent or operator, it is now being intrusted to specialists. Even within the more strictly engineering phases of the mining engineer's work, there is the same tendency toward specialization; his work is being divided up among the electrical engineers, the mechanical engineers, the hydraulic engineers, and others. The opportunities for geologic work, therefore, are distinctly in the direction of specialization. The student in determining the field he shall enter needs to take this fact into account and to prepare accordingly, but not at the sacrifice of the broad basal training. Only a small part of the specialization can be accomplished in college. The remainder will come with experience.

In the future there is likely to be increasing specialization among the different educational institutions in the phases of applied geology which are taught. Geographic location has a good deal to do with this tendency. Where an institution is located near a coal or oil field, it is likely, as a matter of course, to specialize to some extent in the application of geology to these resources. Or, the specialization may arise from the fact that the teachers have had special training in certain phases of applied geology, and such training naturally and properly determines the emphasis to be placed. Courses in engineering geology are finding a natural development in the leading engineering colleges.

In view of the fact that it is impossible for any one institution to cover all phases of applied geology, because of lack of time, and in view of the fact that even if this were attempted the results would be very unequal, because of the varied experience of teachers or because of geographic location, it would seem wise definitely to recognize these limitations and for each institution to play up the work it can do best. With freedom of migration among universities, a student by moving from place to place can thus secure any combination of specialized courses which best fits his requirements.

A DEGREE OF ECONOMIC GEOLOGY

There has been some agitation in recent years for standardization of courses in economic geology, and for the granting of a special degree in evidence of the completion of such a course. The principal argument for this procedure is that it would tend to insure a better average of training and would draw a line between worthy geologists and a host of ill-trained pseudo-geologists. The earth is so accessible, and its use so varied, that geology is handicapped perhaps more than any other science by persons who really have no valid claim to a scientific title.

The writer doubts whether a special degree in economic geology would go far toward improving this situation. Even if the courses were the same in different institutions, the manner of treatment and the ability of the teachers would be so varied that in the future, as in the past, anyone inquiring into the real standing of a geologist would be likely to consider his individual training rather than the degree attached to his name. There would be no guarantee that institutions not qualified to give the degree might not do so. However, the principal objection in the writer's mind to a degree of economic geology is the assumption that it is possible for anybody, in the present stage of knowledge, to formulate a standardized course adequate or best to meet the varied requirements. Considering the breadth and the variety of the field, any such attempt at standardization would have to be highly arbitrary. Once established, it would be a hindrance to the natural development of new courses to meet the ever changing requirements. When, if ever, the science of economic geology becomes fully organized, a standardized course may be possible. In the present stage of the science, more elasticity is required than seems to be possible in any of the courses proposed.

One of the purposes of the introduction of a degree of economic geology, to separate the sheep from the goats, may be accomplished in another way,—namely, by the establishment and maintenance of high standards of admission and high aims on the part of the various professional societies having to do with geology and mining. If this is done, membership in such societies may be regarded as evidence of sound training and achievement. To some extent this procedure may relieve the pressure on universities for uniformity of courses and degrees, leaving them free to develop in such manner as seems best. Scientific organizations, overlooking the entire field, are in a position to take into account the greatest variety of factors of training and experience in selecting their members. Failure of any university course to make men eligible for such recognition will obviously react on the course in a desirable way.

THE OPPORTUNITIES OF THE ECONOMIC GEOLOGIST

It has been the aim in this book to present a general view of the fields of activity of the economic geologist; and the list of chapter headings in itself summarizes the variety of his opportunities. The rapidly increasing use of earth materials promises far greater calls for geologic aid in the future than in the past. The profession is in its infancy.

Opportunities for employment are ordinarily found in three main directions—in educational institutions, in the federal and state geological surveys, and in private organizations. Connection with the United States Geological Survey excludes participation in private work, and in recent years even in teaching. In the state surveys there is ordinarily more latitude in this regard. In the educational institutions, it is rather the common procedure for the instructor to secure his field practice and experience through private agencies, or through part time connection with state surveys,—an arrangement with advantages to all concerned. The educational institution secures the benefit of the field experience which it cannot afford to provide, and is enabled to hold geologists at salaries far below their earning capacity. The geologist gains by the opportunity to alternate between office and field study, and to correct his perspective by the constant checking of theory with field conditions. The combination tends to keep the clearly scientific and the applied phases in a proper relative proportion; it minimizes the danger of drifting into purely empirical field methods on the one hand, and of losing touch with actualities on the other. Geologists devoting their attention solely to field work often complain that they do not have time to digest and correlate their results, nor to keep up with what others are doing. On the other hand, geologists without current field practice are likely to develop too strongly along subjective, deductive, and theoretical lines. The teacher gains in freshness and force in the presentation of his subject in the classroom, and the very effort necessary for presentation requires better analysis and coordination of his field observations. The private or state organization gains in this combination by drawing on the general and varied knowledge which has necessarily been accumulated for teaching and investigative purposes.

Temperament and circumstances will determine in which of these directions the student will turn. However, in view of the present natural tendency to be attracted by the large financial rewards in the commercial field, it may not be out of place to emphasize the fact that these rewards are perhaps more likely to be gained through perfected training and experience in state and national surveys and in educational institutions, than through early concentration in the commercial field. In any case, the financial side will take care of itself when sufficient knowledge and proficiency have been attained in any branch of the science.

The world is the geologist's laboratory; it is the only limit to his activities. The frontiers are near at hand, both physically and intellectually. There are few fields so attractive from the scientific standpoint. There are few in which the successful prosecution of the science can be of so much direct benefit to civilization and can yield such large financial rewards. If, in addition, the opportunities for travel and adventure are taken into account, what profession promises a more interesting and useful life?

So far we have discussed geology as a profession. It has proved its value also as a training for administrative and other public careers. The profession contributes its full share of men to these activities. The practice of geology deals with a wide variety of factors, and requires the constant exercise of judgment in balancing, correlating, and integrating these factors in order to reach sound conclusions. This objective treatment of complex situations is valuable training for the handling of human affairs.

ETHICS OF THE ECONOMIC GEOLOGIST

Ethical questions involved in the practice of economic geology have called out much discussion, and, in some cases, marked differences of opinion among men equally desirous of doing the right thing. In the plain choice between right and wrong, there is of course no difference of opinion. Unfortunately in many of the questions which arise the alternatives are not so clearly labeled.

The lure of discovery and quick returns always has, and doubtless always will, draw into the field large numbers of persons without sound ethical anchorage or standards. Fortunately, these are not the persons in control of the mineral industries; they are mere incidents in the great and stable business built up by legitimate demands for raw materials.

The view is sometimes expressed that the geologist should hold himself aloof from the business or applied phases of his profession, because of the danger of being tainted with commercialism. This argument would apply to the engineer as well as to the geologist. To carry such a procedure through to its logical conclusion would mean substantially the withdrawal of scientific aid from industry,—which, to the writer, is hardly a debatable question. Circumstances are trending inevitably to the larger use of geologic science in the commercial field. The problems of ethics cannot be solved by staying out. The economic geologist is rather called upon to do his part in raising the standards of ethics in that part of the field in which he has influence. This he can do by careful appraisal of all the conditions relating to a problem which he is asked to take up, and by refusing to act where questionable ethical standards are apparent or suspected. He must understand fully the purposes for which his report is to be used; merely as a matter of professional self-interest, there is no other course open to him. In a field in which there is so much danger from loose ethical conceptions, the premium on rigid honesty and nice appreciation of professional ethics is proportionately higher. The extreme care taken in this matter by acknowledged leaders in the profession of economic geology should be carefully considered by the young man entering the profession. There is a reason.

In other chapters reference is made to certain special ethical questions, such as the use of geology in mining litigation (pp. 349-355), and the necessity of the geologist's recognizing his own limitations (pp. 92-94), but no attempt has been made to cover the variety of such questions that may come up. It is safe to assume that no special ethical code can be made sufficiently comprehensive, detailed, and elastic to cover all the contingencies which are likely to be met in the practice of economic geology; nor is it likely that any such code, if attempted, would be any improvement on the spirit of the Golden Rule. Simple decency and common sense in their broader implications are essential to the practice of the profession.



INDEX

Abrasives, 267-270, 397

Abyssinia, potash, 112

Adams, Frank D., 367

Adirondacks, New York, graphite, 282 iron ores, 160, 162, 163, 171 phosphate from magnetic ores, 105-106 use of magnetic surveys in tracing iron rocks, 317

Ad valorem method of valuation of mineral deposits, 331-335

Africa, bauxite, 242 coal, 116 cobalt, 255 copper, 197-198, 205 tin, 260 See also South Africa; North Africa; East Africa; West Africa. Alabama, bauxite, 243, 245 graphite, 281 iron, 52-53, 160, 162, 163, 166-167

Alaska, antimony, 248 copper, 36, 41, 47, 49, 199, 200-201 gold, 222, 224, 229 silver, 234 tin, 261, 262

Algeria, antimony, 247, 248 gypsum, 283 iron, 156, 160, 161, 194 petroleum, 128 phosphates, 104, 105, 106 See also North Africa.

Almaden, Spain, mercury ores, 256-257, 259

Alsace, potash, 111-113

Alsace-Lorraine, coal and iron of, under Peace Treaty, 401-402

Aluminum Company of America, 243

Aluminum ores, 241-246, 397 See also Bauxite.

Alunite, 39, 41-42, 112, 114, 230

Anaconda, Montana, arsenic production, 250

Anaconda Copper Mining Company, manufacture of phosphate, 105 use of geology in development and exploration, 326-327

Anamorphism, defined, 27, 57

Anamorphism of mineral deposits, 26, 57-58

Anhydrite, occurrence in gypsum deposits, 284-285

Anticlines, occurrence of oil in, 141-142, 147-148

Antimonial lead, 246

Antimony ores, 246-249, 398

Apex law, 349-350, 353

Aplites, 35

Appalachians, barite, 274 bauxite, 245 graphite, 282-283 petroleum, 132, 135 pitchblende, 266 pyrite, 108 tin, 262 See also under individual states.

Argentina, borax, 275 mica, 286 petroleum, 128 tungsten, 183

Arizona, asbestos, 271, 272 copper, 33, 38, 41, 47, 48, 198-199, 203, 204-205, 208, 314, 316 gold, 222 manganese, 175 molybdenum, 186,187 silver, 234 tungsten, 183 turquoise, 293

Arkansas, bauxite, 96, 243, 244-245, 246 diamonds, 292 fuller's earth, 279 hones, oilstones and whetstones, 269 phosphates, 105 zinc, 215

Arnold, Ralph, 134, 136, 149-150

Arsenic ores, 249-251, 397

Artesian wells, 73

Asbestos, 270-272, 398

Asphalt and bitumen, 56, 151-153, 397

Atolia, California, tungsten ores, 185

Atwood, W. W., 414

Australasia, cement, 87 coal, 116 gold, 222

Australia, antimony, 247 arsenic, 250 asbestos, 271, 272 bauxite, 242 bismuth, 252 coal, 115 copper, 197-198 gold, 41, 222, 224 iron, 154, 164, 165 lead, 210-211, 212 molybdenum, 186 phosphates, 105 silver, 232 tin, 260 tungsten, 183 zinc, 214-215, 216

Australia, laws relating to ownership of mineral resources, 343, 345

Austria, cement, 87 graphite, 280 mercury, 256, 257 molybdenum, 186 talc, 299 uranium and radium, 264 zinc, 214

Austria-Hungary, barite, 272 coal, 115, 116 iron, 160, 161 magnesite, 191-193 manganese, 174 silver, 232 See also Hungary.

Austria-Hungary, commercial and political control of various minerals, 64

Ball clay, 85, 398

"Bar" theory of formation of thick salt beds, 297

Baraboo, Wisconsin, quartzites of, 82

Barite, 272-274, 397

Basalt, 17, 19, 82, 90

Bauxite, 9, 50, 96, 241-246, 397

Bavaria, graphite, 280

Bawdwin Mines, Burma, lead and zinc, 209, 214

Beaumont Field, Texas, occurrence of oil, 148

Belgian Congo, cobalt, 255 copper, 205

Belgium, barite, 272 cement, 87 coal, 115-117, 127, 401 flint linings, 269 iron, 160-161 lead, 54-55, 210 millstones and buhrstones, 269 phosphates, 104 zinc, 54-55, 214

Belgium, commercial and political control of various minerals, 64, 280

Belle Isle, Newfoundland, iron ores, 52-53, 160, 166

Bergholm, Carl, 319

Bergstrom, Gunnar, 319

Bessemer processes of steel making, 158, 161

Bilbao, Spain; iron ores, 160, 170

Billingsley, Paul, and Grimes, J. A., 44

Bingham, Utah, copper and lead ores, 37, 42, 47, 199, 203, 204, 207, 208, 212, 314

Birmingham, Alabama, iron ores, 160, 162, 163, 166-167 See also Clinton iron ores.

Bisbee, Arizona, copper ores, 47, 198, 204, 314, 316

Bismuth ores, 252-253, 397

Bitumen and asphalt, 56, 151-153, 397

Black Hills, South Dakota, gold ores, 228, 229 tin ores, 262

"Blue ground," occurrence of diamonds in, 291

"Bluestone," 84

Bohemia, uranium and radium ores, 265

Boise Basin, Idaho, monazite deposits, 289

Boleo, Lower California, copper ores, 201

Bolivia, antimony, 247 bismuth, 252, 253 borax, 275 copper, 206 nitrates, 103 petroleum, 128 silver, 232 tin, 261, 262-263 tungsten, 183, 184

Bolivia, commercial and political control of various minerals, 64

Bonne Terre limestone, Missouri, zinc ores, 217

Boone formation, Missouri, zinc ores, 217

Borax, 274-277, 397

Borax Lake, California, borax deposits, 276

Borneo, diamond dust, 268 platinum, 238

Bort, 267, 268, 398

Boulder batholith, Montana, ore-deposits of, 44

Boulder County, Colorado, tungsten ores, 184

Braden copper ores, Chile, 199

Brazil, chromite, 179 coal, 116 diamonds and diamond dust, 268, 292 graphite, 280 iron, 52-53, 162, 165, 167, 313 manganese, 174-175, 176 mica, 286 monazite, 288, 289 oil shales, 151 zirconium, 189-190

Brazil, commercial and political control of various minerals, 64

Briey district, France, iron ores, 161, 163 vanadium, 187

Brinton, Virginia, arsenic ores, 251

British Coal Commission, 367

British Columbia, laws relating to mineral resources, 344

British Empire. See Great Britain.

British Guiana, bauxite, 242, 243

British South Africa, coal, 116

Broken Hill, New South Wales, lead and zinc ores, 209, 212

Bromine, 277-278, 397

Brooks, Alfred H., 404, 408

Brooks, Alfred H., and LaCroix, Morris F., 404

Buhrstones, 269

Building stone, 80-84, 88-90, 397

Bureau of Mines, 403, 406

Burma, lead, 209, 210, 212 rubies, 289, 292 silver, 233 tungsten, 183, 185 zinc, 214, 216

Burrows, J. S., 367

Butler, B. S., Loughlin, G. F., and Heikes, V. C., 44, 55, 230

Butte, Montana, arsenic in copper ores, 251 copper ores, 40, 47, 49, 198-199, 201-203, 207, 208 manganese ores, 177, 314 silver ores, 234, 314 use of placers in locating ores, 316 zinc ores, 215-216 zonal arrangement of minerals, 42, 44

Cadmium ores, 253-254, 397

California, antimony, 248 asbestos, 271 asphalt and bitumen, 152 basalt, 82 borax, 275, 276-277 chromite, 179 copper, 199, 204 diatomaceous earth, 269 fuller's earth, 279 gold, 222, 224, 227, 229, 308, 316, 342 granite, 82 graphite, 281 grinding pebbles, 268 magnesite, 191-193 manganese, 175 mercury, 40, 256, 257, 259 natural gas, 151 petroleum, 132, 133, 135, 137 potash, 112, 113-114 pyrite, 108 serpentine, 83 silver, 234, 308 tourmaline, 293 tungsten, 183

Campbell, J. Morrow, 185

Campbell, M. R., 121, 122, 366

Campbell, M. R., and Parker, E. W., 367, 370-371

Canada, arsenic, 250 asbestos, 270-271, 272 cement, 87 chromite, 179 coal, 115, 116 cobalt, 255 copper, 197-198 corundum, 268, 270 feldspar, 86 fluorspar, 193, 194 gold, 222 graphite, 280-281 grindstones and pulpstones, 269 gypsum, 283-284 iron, 52-53, 155, 156, 160, 165 magnesite, 191-193 mica, 286, 287 molybdenum, 186 natural gas, 151 nickel, 180-182 petroleum, 128 phosphates, 105, 106 platinum, 238 pyrite, 107-108 salt, 294 silver, 232, 234-235 talc, 299, 300 titanium, 190 zinc, 214, 215

Canada, laws relating to ownership to mineral resources, 343 use of magnetic surveys in tracing iron rocks, 317

Cananea, Sonora, Mexico, copper ores, 203

Cannel coal, 125

Cape Colony, South Africa, asbestos, 272

Capillarity, effect on ground-water level, 70 effect on petroleum migration, 142-143

Capital value of mineral resources, 64, 328

"Capping," of copper ores, 47

Carbonado, 268

Carey Act, classification of public lands under, 310

Carmel, New York, arsenic ores, 251

Casing-head gasoline, 139, 151

Caucasus region, Russia, manganese ores, 174, 176

Cement, 86-88, 397

Cementation, mineral products resulting from, 24

Cementing materials, source of, 25

Central America, cement, 87, 88 silver, 232 See also Costa Rica, Guatemala, Panama.

Central Powers. See Germany, Austria-Hungary.

Cerium ores, See Monazite.

Ceylon, graphite, 280-283 mica, 286

Chalk, 83, 398

Chamberlin, T. C., 217

Chamberlin, T. C., and Salisbury, R. D., 415

Chance, H. M., 367, 368

Chert, use for abrasives, 267, 268, 270

Chile, borax, 275, 276 bromine, 277 coal, 116 copper, 197-199, 203 iron, 155, 161, 162, 164, 171 manganese, 176 nitrates, 100, 101-104 phosphates, 105, 106 potash, 112 silver, 232 sulphur, 109-110

Chile, commercial and political control of various minerals, 64, 261

China, antimony, 247-248, 249 arsenic, 250, 251 bismuth, 252 coal, 115, 116, 127, 154 iron, 154, 160, 164, 165, 171 petroleum, 128 salt, 294 silver, 232 tin, 260 tungsten, 183, 184

China, commercial and political control of various minerals, 64

"Chloriding" for silver ores, 314

Chrome (or chromite) ores, 178-180, 307, 365-366, 398

Clarke, F. W., 13, 17, 18

Classification of mineral deposits, 27-59 of mineral lands, 309-311 of mineral materials, adjustment of scientific to commercial names, 356

Clays, 18, 85, 91-92, 398

Cle Elum, Washington, iron ores, 58

Cleavage, 26

Cleveland district, England, iron ores, 161

Clifton-Morenci district, Arizona, copper ores, 38, 198

Climate, as a factor in exploration, 315 effect of in formation of bauxites, 246

Clinton iron ores, 9, 52-53, 163, 166-167, 218, 313, 317

Coal, conservation of, 365, 366-382 European international situation, 116-117, 386, 387, 393, 400-403 general economic and geologic features, 56, 115-127, 309, 397 reserves, 116, 360-361, 366-367

Cobalt district, Ontario, arsenic, 251 cobalt, 255 silver ores, 232, 234-235, 308, 316 use of coefficient to estimate future output, 322

Cobalt ores, 254-255, 398

Coeur d'Alene district, Idaho, lead-silver ores, 39, 45, 211, 212-213, 216, 234

Coke, 118-119

Colloids, content of in clays, 92

Colombia, coal, 116 emeralds, 289, 293 gold, 222 platinum, 238

Colombia, commercial and political control of various minerals, 64

"Colorado," 313

Colorado, arsenic, 250 asphalt and bitumen, 152 bismuth, 253 coal, 117 fluorspar, 194 gold, 222, 230 graphite, 281 lead, 211, 212 molybdenum, 186 oil shales, 150 petroleum, 133 silver, 234 tungsten, 183, 184 turquoise, 293 uranium and radium, 264-265, 266 vanadium, 187-188 zinc, 216, 219-220

Commercial and political control of mineral resources, 65, 387, 388 See also under individual resources.

Common rocks, as mineral resources, 80-94

Comstock Lode, Nevada, silver ores, 235-236, 308

Congo. See Belgian Congo

Connecticut, basalt, 82 diatomaceous earth, 269 tourmaline, 293

Conover, Julian D., 12

Conservation, 359-382, 393-395 application of economic geology to, 1-2 of coal, 366-382 of common rocks, 81 of human energy, 362 international aspects, 362-363, 375, 376-377, 393-395 of petroleum, 137-139

Conservation Commission of Canada, 367

Contact metamorphism, 20, 24, 25-27, 36-37 See also Igneous after-effects.

Contracts, classification of earth materials in, 356-357

Copper ores, 9, 36-50, 51-52, 55, 197, 209, 307, 308-309, 313-314, 318, 396

Cornwall, England, tin ores, 42, 260, 262, 263 uranium and radium ores, 264

Corocoro, Bolivia, copper ores, 206

Corundum, 267-268, 270, 398

Costa Rica, manganese, 176

"Cracking" processes for refining petroleum, 137, 139

Cripple Creek district, Colorado, gold ores, 230

Cuba, chromite, 179 copper, 197 iron, 8-9, 50, 58, 96, 155, 160, 163, 171-173, 313, 349 manganese, 175 nickel, 181 petroleum, 128

Cuyuna Range, Minnesota, manganese ores, 175, 177

Cycle, erosion or topographic, 6-7

Cyclic nature of ore concentration, 7-8, 47-48, 56, 169, 201, 205, 208, 325

Cyprus, asbestos, 271, 272

Dams, geologic problems involved in construction, 414

Davis, W. M., 408

Death Valley, California, borax deposits, 276

Degree of economic geology, 427-428

Denmark, cement, 87 chalk, 83 grinding pebbles, 268

Depletion of mineral deposits, as factor in valuation and taxation, 331, 337, 339

Depth as a factor in mineral deposition, 43, 49, 58-59

Diamond dust, 267, 268, 398

Diamonds, 289-292, 316, 317

Diatomaceous earth, 267, 269, 398

Diorite, 82

Dolomite, 23, 192

Domes, occurrence of oil in. See Anticlines.

Domes, salt and sulphur, Gulf Coast, 110, 298

Drilling, exploration of mineral deposits by, 320-321

Drilling records, public registration of, 305-306

Ducktown, Tennessee, copper ores, 204

Dutch East Indies, natural gas, 151 petroleum, 128, 129 tin, 260 use of coefficient to estimate tin reserves, 322

Dutch Guiana, bauxite, 243

Dutch West Indies, phosphates, 105, 106

Dynamic metamorphism, 25-26

East Africa, mica, 286

East Indies. See Dutch East Indies.

Eckel, E. C., 404

Economic Liaison Committee, 406

Egypt, petroleum, 128 phosphates, 104

Eiserner Hut, 313

Electrical conductivity, use in exploration of mineral deposits, 319

Ely, Nevada, copper ores, 41, 203

Emeralds, 289, 291, 293

Emery, 267-268, 270, 397, 398

Emmons, W. H., 43

Empire, Colorado, molybdenum ores, 186

Energy resources, 115-153 accelerating production of, 64, 130-131, 361, 366-367

Engineering, application of economic geology to, 2, 413-419

England. See Great Britain

Enrichment, secondary, 7-8, 25, 46-50. See also under Copper ores, silver ores, etc.

Epigenetic ore deposits, use of term, 32, 36

"Equated Income" method of taxation, 335-336

Erosion, relation to oxide zones, 47-48

Erosion cycle, description of, 6-7

Ethics, questions of, 430-431

Europe, coal and iron situation under terms of Peace Treaty, 400-403

Expert witnesses, use of geologists as, 349-355, 357-358

Exploitation of mineral deposits, functions of geologist, 326-327

Exploration of mineral deposits, 301-327 effect of ownership laws on, 347-349 effect of taxation on, 339-341 quantitative aspects of, 321-322, 324-326 relation to international conditions, 395-396

Extralateral rights, litigation affecting, 349-355

Extrusive rocks, formation of, 19

Federated Malay States. See Malay States.

Feldspar, 16, 86, 268-269, 397

Ferro-alloy minerals, 156-158, 173-196, 307, 362-363, 365-366, 393-394, 397-398

Ferroboron, 275

Ferrocerium, 288

Ferrochrome, 178

Ferromanganese, 173-174

Ferromolybdenum, 186

Ferrosilicon, 195

Ferrotitanium, 190

Ferrotungsten, 182-183

Ferrovanadium, 187

Ferrozirconium, 189

Ferruginous chert, 167

Fertilizer minerals, 99-114

Field work for students of economic geology, 425-426

Flint linings for tube mills, 269

Florida, fuller's earth, 279 phosphates, 105, 107 titanium, 190, 191 zirconium, 189

Flowage, rock, 25, 26

Fluorspar, 193-194, 397

Foothill district, California, copper ores, 204

Formosa, petroleum, 128

Foundations, application of geology to, 413

France, antimony, 247, 249 arsenic, 250-251 asphalt and bitumen, 152 barite, 272 bauxite, 242, 245 cement, 87 chalk, 83 coal, 115-117, 127 coal and iron situation under Peace Treaty, 400-403 fluorspar, 194 grinding pebbles, 268 gypsum, 283 iron, 154, 160-162, 163, 166-167, 402-403 manganese, 176 millstones and buhrstones, 269 molding sand, 84 oil shales, 150 phosphates, 104, 105 potash, 111-113 salt, 294 talc, 299 vanadium, 187 zinc, 214

France, control of various minerals in other countries, 64, 104-105, 178, 180, 210, 215, 222, 238, 247, 261, 280 laws relating to ownership of mineral resources, 343 relative position in regard to supplies of minerals, 399

Franklin Furnace, New Jersey, zinc ores, 215-216, 220

"Freestone," 84

French Guiana, bauxite, 242

Fuel ratio of coal, defined, 120

Fuller's earth, 278-279, 397

Gabbro, 19, 82

Gale, Hoyt S., 111

Galena dolomite, Wisconsin, zinc ores, 217

Galicia, petroleum, 128, 129 potash, 112

Ganister, 84, 91, 195

Garnet, 267, 268, 270, 398

Gas, natural, 57, 151

Georgia, asbestos, 271, 272 barite, 273 bauxite, 243, 245 corundum, 270 fuller's earth, 279 marble, 83

Georgia granite, volume change in weathering of, 21

Germany, arsenic, 250-251 barite, 272-273 bismuth, 252 borax, 275, 277 bromine, 277, 278 cadmium, 253, 254 cement, 87 coal, 115-117, 127, 400-403 copper, 9, 52, 197-198, 206 fluorspar, 194 gypsum, 283 iron, 154, 160-162, 402-403 lead, 54-55, 210-211 lignites, 379, 402 millstones and buhrstones, 269 nitrates, manufactured, 101-102 petroleum, 128 potash, 111-112 salt, 294, 297 silver, 232 tripoli and rottenstone, 269 uranium and radium, 264 zinc, 54-55, 214-215, 216 zirconium, 189

Germany, control of various minerals in other countries, 64, 174, 183, 189, 198, 211, 215, 222, 232, 257, 261, 271, 288, 387 participation of government in mineral trade, 388 relative position in regard to supplies of minerals, 399

Geysers, 72

Gilbert, Chester G., 123

Gilbert, Chester G., and Pogue, Joseph E., 119, 134, 138

Gilpin County, Colorado, uranium ores, 266

Glacial geology, application to railroad building, 418 application to road materials, 91, 418

Glacial soils, 95

Globe, Arizona, copper ores, 198

Gneissic structure, 26

Gogebic district, Michigan, iron ores, 312, 318, 325-326

Gold, monetary reserves, 223

Gold Coast, West Africa, manganese, 176

Gold ores, 36-50, 51, 221-230, 308-309, 313-314, 397

Goldfield, Nevada, alunite, 41-42, 114 bismuth, 253 gold-silver ores, 36, 39, 230, 308

Gossan, 47, 109, 173, 313

Government ownership and control. See Nationalization.

Governments, participation in mineral ownership and international trade, 388-390

Granite, 17, 19, 82, 90

Graphite, 279-283, 398

Graphite Association, Southern, 405

Gravel, sand and, 84-85

Gray, F. W., 368

Great Basin, Nevada, covering of mineral deposits by lavas, 311-312 gold-silver ores, occurrence in a metallogenic province, 308 tungsten ores, 185

Great Britain, arsenic, 250 barite, 272 cadmium, 253 cement, 78 chalk, 83 clay, 85 coal, 115-117, 126, 127 fluorspar, 193-194 fuller's earth, 278-279 grindstones and pulpstones, 269 gypsum, 283 iron, 154, 160-161, 163 manganese, 176 salt, 294 tripoli and rottenstone, 269 uranium and radium, 264

Great Britain, control of various minerals outside of British Isles, 64, 101, 104-105, 132, 152, 165, 178, 181, 183, 198, 210, 214, 222, 225, 232, 242, 247, 252, 256-257, 260, 275, 280 income taxes on mineral properties, 337, 339 laws relating to ownership of mineral resources, 343 participation of government in mineral trade, 388 relative position, in regard to supplies of minerals, 399 tendencies toward nationalization, 346

Great Plains, lignite, 118 pumice, 268

Greece, chromite, 178-179 emery, 268, 270 magnesite, 191-193 zinc, 214

Greenland, graphite, 280

Gregory, Herbert, 407, 413

Grimes, J. A., and Billingsley, Paul, 44

Grinding pebbles, 267, 268, 270, 398

Grindstones, 269

Ground-waters, composition of and relation to commercial use, 73-75 distribution and movement of, 68-72 influence in deposition of ore deposits, 41-42 relation to military operations, 78-79, 408, 410-411 relation to rock slides, 78, 416-417 source of, 68

Ground-water level, description of, 70 relation to oxide zone, 48 relation to zone of weathering, 22

Ground-water supply, relation of geology to, 75-76

Guano, 104, 106

Guatemala, chromite, 179

Guiana, bauxite, 242-243

Gulf Coast region, lignite, 118 petroleum, 132, 135, 137 salt, 298 sulphur, 110 See also Louisiana, Texas, etc.

Gypsum, 100, 283-285, 397

Haas, Frank, 367, 369

"Head" of underground water, 71-73

Heikes, V. C., Butler, B. S., and Loughlin, G. F., 44, 55, 230

Highway building, application of geology to, 90-91

Holland, cement, 87 commercial and political control of various minerals, 64 See also Dutch East Indies, etc.

Homestake Mine, South Dakota, gold ores, 229

Hones, 269

Hoover, Herbert C., 322

Hot springs, relation to ore-deposits, 40, 258-259

Hot waters, evidence of formation of ores by, 37-41

Huancavelica district, Peru, mercury ores, 258

Hudson River, physiographic problems in tunneling under, 415

Hudson's Bay, possible diamond field, 317

Humus, 94

Hunan Province, China, antimony ores, 249

Hungary, antimony, 247 natural gas, 151 See also Austria-Hungary.

Hydrosphere, 18

Hypogene ores, use of term, 32-33

Idaho, coal, 117 lead, 39, 45, 209, 211, 212-213 monazite, 289 phosphates, 105 silver, 234 zinc, 214, 216

Idria, Austria-Hungary, mercury ores, 257

Igneous after-effects, ore-deposits formed as, 19-20, 36-46

Igneous rocks, formation of, 19 mineral deposits associated with, 19-20, 34-46 principal minerals of, 14-16 proportions of principal types, 17 relative abundance of, 17 weathering of, 20

Illinois, clay, 85 coal, 115, 117, 126 fluorspar, 194 limestone, 83 petroleum, 132, 133, 135 pyrite, 109 sand and gravel, 85 tripoli and rottenstone, 269 zinc, 216

Illinois Geological Survey, cooperative exploration for oil, 147, 306

Income tax, application to mineral properties, 336-339

India, bauxite, 242

India, bromine, 277 chromite, 178-179 coal, 115, 116 corundum, 268 diamond dust, 268 gypsum, 283 iron, 154, 164, 165 manganese, 174-176 mica, 286 monazite, 288, 289 petroleum, 128, 129 platinum, 238 salt, 294 zirconium, 189

Indiana, coal, 117, 126 hones, oilstones and whetstones, 269 limestones, 83 petroleum, 133, 135

Interest rate, as a guide in conservation, 364 choice of for valuation purposes, 233 limiting effect on acquirement of reserves, 334

International aspects of mineral resources, 2, 383-404

International Coal Commission, 387, 393, 402

International trade, in common rocks, 80 in minerals, 383-388 participation of governments, 388-390

Intrusive rocks, formation of, 19

Iowa, flint linings, 269 grinding pebbles, 268 gypsum, 284 zinc, 216

Ireland, bauxite, 242

Iron and coal, situation of western Europe under terms of Peace Treaty, 400-403

Iron and steel, metallurgical processes, 158-159

Iron and steel industry, possible establishment on west coast of United States, 155, 165

Iron cap, of sulphide deposits, 47, 109, 313

Iron ores, anti-conservational effect of war, 365 attempt to estimate reserves of continents, 322 exploration of in Lake Superior region, 323-326 general geologic and economic features, 8-9, 28, 34, 36, 47, 50, 52-53, 55-56, 58, 96, 153-156, 158-173, 397 litigation concerning Cuban, 349 metallogenic provinces and epochs, 308-309 outcrops, 312-313 taxation of in Lake Superior region, 335 use of magnetic surveys, 317-318 world reserves, 162-165, 360-361

Itabirite, 167

Italy, asbestos, 271, 272 asphalt and bitumen, 152 barite, 272 bauxite, 242 borax, 275 cement, 87 graphite, 280 manganese, 176 marble, 83 mercury, 256-257 natural gas, 151 petroleum, 128 pumice, 268 salt, 294 sulphur, 109-110 talc, 299 zinc, 214-215

Italy, coal situation under Peace Treaty, 401 commercial and political control of various minerals, 64 relative position in regard to supplies of minerals, 399

Japan, arsenic, 250 cement, 87 chromite, 178-179 coal, 115, 117 copper, 197-198 gold, 222 graphite, 280 iron, 154, 160 manganese, 174 natural gas, 151 petroleum, 128 silver, 232 sulphur, 109-110 tungsten, 183, 185 zinc, 214

Japan, control of various minerals in other countries, 64, 105, 154, 247

Jasper, 167

Java, manganese, 176

Jerome, Arizona, copper ores, 41, 47, 198, 204-205, 314

Joachimsthal, Bohemia, uranium and radium ores, 265

Joint Mineral Information Board, 406

Joplin district, Missouri, cadmium, 254 lead and zinc ores, 54-55, 209, 211, 214, 215, 216-219

Juneau, Alaska, gold ores, 229

Kansas, gypsite, 284 natural gas, 151 petroleum, 132, 133, 135 salt, 294 zinc, 215

Kaolin, 85, 398

Katamorphism, defined, 27, 57

Katanga, Belgian Congo, cobalt, 255 copper ores, 205

Kennecott, Alaska, copper ores, 36, 41, 47, 49, 200-201

Kentucky, asphalt and bitumen, 152, 153 coal, 117 fluorspar, 194 marble, 83 petroleum, 133 sandstone, 84

Kimberley, South Africa, diamonds, 291-292

Knox dolomite, Tennessee, zinc ores, 219

Korea, gold, 222 graphite, 280, 282 iron, 160 molybdenum, 186 tungsten, 183

Lacroix, Morris F., and Brooks, Alfred H., 404

Lake Superior copper ores, 36, 52, 200, 206

Lake Superior copper, silver, gold ores, occurrence in a metallogenic province, 308

Lake Superior iron ores, 8, 47, 55-56, 160, 162, 163, 167-170, 309, 312-313

Lake Superior region, iron ore exploration in, 317-318, 323-326

Land grants in United States, retarding effect on exploration, 349

"Land-plaster", 100

Laterites, 172-173

Laws relating to mineral resources, 342-358

Lawton region, Pennsylvania, coal, 117

Lead and zinc, Wisconsin, equated income method of taxation, 335-336

Lead ores, 36-50, 54-55, 209-213, 307, 308, 313-314, 361, 397

Leadville, Colorado, bismuth, 253 lead and zinc ores, 212, 216, 219-220

Leasing law, on public lands in western United States, 348

Leith, C. K., 323

Leith, C. K., and Mead, W. J., 45

Leith, C. K., and Van Hise, C. R., 56, 324

Lesher, C. E., and Smith, George Otis, 371, 372, 373, 375

Lignite, 118, 120, 122, 124 German development of, 379, 402

Lime, 82, 99-100, 397

Limestone, 15, 17, 23, 82-83, 89-90, 91

Lincolnshire district, England, iron ores, 161

Lindgren, W., 43

Lipari Islands, Italy, pumice, 268

Lithosphere, principal elements of, 13 principal minerals of, 14-16 principal rocks of, 16-17

Litigation, use of geologists in, 349-355, 357-358

Lode, application of legal term to diverse mineral deposits, 350

Long-wall system of coal mining, conservational aspect, 368 subsidence of overlying ground and resulting litigation, 357, 417

Longwy, France, iron ores, 161

Lorraine, iron ores, 52-53, 161-162, 163, 166, 364, 402-403 phosphate from Thomas slag, 104

Loughlin, G. F., Butler, B. S., and Heikes, V. C., 44, 55, 230

Louisiana, natural gas, 151 petroleum, 132, 133, 135 salt, 298 sulphur, 110

Lower California, copper, 201 magnesite, 191-192

Luxemburg, coal situation under Peace Treaty, 401 iron ores, 160-162, 163 See also under Lorraine, iron ores

Madagascar, corundum, 268 graphite, 280-282

Magmatic segregation, mineral deposits thus formed, 34-35, 59

Magmatic waters, evidence of formation of ores by, 37-41

Magnesite, 191-193, 397

Magnetic surveys in tracing mineral ledges, 317-318

Magnetite deposits, 34, 171, 191, 317-318

Maine, feldspar, 86 granite, 82 tourmaline, 293

Malay States, tin, 260-261 tungsten, 183

Manchuria, iron, 160

Mandatory countries, exploitation of minerals in, 390-391

Manganese ores, 47, 55, 173-178, 314, 386, 398

Mansfield shales, Germany, copper ores, 9, 52, 206

Mantle rock, 22

Mapimi, Mexico, arsenic production, 250

Marble, 83, 89-90

Marbut, Curtis F., 95

Marl, 83

Marquette district, Michigan, iron ore outcrops, 312

Maryland, diatomaceous earth, 269 serpentine, 83

Marysville, Utah, alunite deposits, 114

Mashing, 25-26

Massachusetts, granite, 82 serpentine, 83

McCoy, A. W., 142

Mead, Daniel W., 69, 77-78

Mead, W. J., 245

Mead, W. J., and Leith, C. K., 45

Mehl, M. G., 144

Menominee district, Michigan, iron ore outcrops, 312

Mercury ores, 40, 255-260, 398

Mesabi district, Minnesota, concentration of siliceous iron ores, 156 exploration for iron ores, 313, 318, 324, 325

Mesopotamia, petroleum, 128-130, 137, 391

Mesothorium, 288

Metallogenic provinces and epochs, 308-309

Metamorphic cycle and its relation to classification of mineral deposits, 27-28

"Metamorphic rocks," defined, 27

Metamorphism, relation to economic geology, 10 use of principles of in exploration for mineral deposits, 319-320 See also Katamorphism, Anamorphism, Contact metamorphism, Dynamic metamorphism, Weathering, etc.

Metasomatic replacement, 24

Metcalf-Morenci district, Arizona, copper ores, 38, 198

Meteoric waters, influence of in deposition of ore deposits, 25, 41-42

Mexico, antimony, 247-248 arsenic, 250 cement, 87 copper, 197-198, 201, 203 gold, 222 graphite, 280-282, 283 lead, 210-211 magnesite, 191-192 mercury, 256, 258 molybdenum, 186 natural gas, 151 petroleum, 128, 129, 137, 144 silver, 231-232, 233 vanadium, 188 zinc, 214-215