What changes in the forests of your region would be brought about, and in what way, if the climate should very gradually grow colder? What changes if it should grow warmer?

On the Alps and the highest summits of the White Mountains of New England are found colonies of arctic species of plants and insects. How did they come to be thus separated from their home beyond the arctic circle by a thousand miles and more of temperate climate impossible to cross?

MAN. Along with the remains of the characteristic animals of the time which are now extinct there have been found in deposits of the Glacial epoch in the Old World relics of Pleistocene MAN, his bones, and articles of his manufacture. In Europe, where they have best been studied, human relics occur chiefly in peat bogs, in loess, in caverns where man made his home, and in high river terraces sometimes eighty and a hundred feet above the present flood plains of the streams.

In order to understand the development of early man, we should know that prehistoric peoples are ranked according to the materials of which their tools were made and the skill shown in their manufacture. There are thus four well-marked stages of human culture preceding the written annals of history:

4 The Iron stage. 3 The Bronze stage. 2 The Neolithic (recent stone) stage. 1 The Paleolithic (ancient stone) stage.

In the Neolithic stage the use of the metals had not yet been learned, but tools of stone were carefully shaped and polished. To this stage the North American Indian belonged at the time of the discovery of the continent. In the Paleolithic stage, stone implements were chipped to rude shapes and left unpolished. This, the lowest state of human culture, has been outgrown by nearly every savage tribe now on earth. A still earlier stage may once have existed, when man had not learned so much as to shape his weapons to his needs, but used chance pebbles and rock splinters in their natural forms; of such a stage, however, we have no evidence.

PALEOLITHIC MAN IN EUROPE. It was to the Paleolithic stage that the earliest men belonged whose relics are found in Europe. They had learned to knock off two-edged flakes from flint pebbles, and to work them into simple weapons. The great discovery had been made that fire could be kindled and made use of, as the charcoal and the stones discolored by heat of their ancient hearths attest. Caves and shelters beneath overhanging cliffs were their homes or camping places. Paleolithic man was a savage of the lowest type, who lived by hunting the wild beasts of the time.

Skeletons found in certain caves in Belgium and France represent perhaps the earliest race yet found in Europe. These short, broad- shouldered men, muscular, with bent knees and stooping gait, low- browed and small of brain, were of little intelligence and yet truly human.

The remains of Pleistocene man are naturally found either in caverns, where they escaped destruction by the ice sheets, or in deposits outside the glaciated area. In both cases it is extremely difficult, or quite impossible, to assign the remains to definite glacial or interglacial times. Their relative age is best told by the fauna with which they are associated. Thus the oldest relics of man are found with the animals of the late Tertiary or early Quaternary, such as a species of hippopotamus and an elephant more ancient than the mammoth. Later in age are the remains found along with the mammoth, cave bear and cave hyena, and other animals of glacial time which are now extinct; while more recent still are those associated with the reindeer, which in the last ice invasion roamed widely with the mammoth over central Europe.

THE CAVES OF SOUTHERN FRANCE. These contain the fullest records of the race, much like the Eskimos in bodily frame, which lived in western Europe at the time of the mammoth and the reindeer. The floors of these caves are covered with a layer of bone fragments, the remains of many meals, and here are found also various articles of handicraft. In this way we know that the savages who made these caves their homes fished with harpoons of bone, and hunted with spears and darts tipped with flint and horn. The larger bones are split for the extraction of the marrow. Among such fragments no split human bones are found; this people, therefore, were not cannibals. Bone needles imply the art of sewing, and therefore the use of clothing, made no doubt of skins; while various ornaments, such as necklaces of shells, show how ancient is the love of personal adornment. Pottery was not yet invented. There is no sign of agriculture. No animals had yet been domesticated; not even man's earliest friend, the dog. Certain implements, perhaps used as the insignia of office, suggest a rude tribal organization and the beginnings of the state. The remains of funeral feasts in front of caverns used as tombs point to a religion and the belief in a life beyond the grave. In the caverns of southern France are found also the beginnings of the arts of painting and of sculpture. With surprising skill these Paleolithic men sketched on bits of ivory the mammoth with his long hair and huge curved tusks, frescoed their cavern walls with pictures of the bison and other animals, and carved reindeer on their dagger heads.

EARLY MAN ON OTHER CONTINENTS. Paleolithic flints curiously like those of western Europe are found also in many regions of the Old World,—in India, Egypt, and Asia Minor,—beneath the earliest vestiges of the civilization of those ancient seats, and sometimes associated with the fauna of the Glacial epoch.

In Java there were found in 1891, in strata early Quaternary or late Pliocene in age, parts of a skeleton of lower grade, if not of greater antiquity, than any human remains now known. Pithecanthropus erectus, as the creature has been named, walked erect, as its thigh bone shows, but the skull and teeth indicate a close affinity with the ape.

In North America there have been reported many finds of human relics in valley trains, loess, old river gravels buried beneath lava flows, and other deposits of supposed glacial age; but in the opinion of some geologists sufficient proof of the existence of man in America in glacial times has not as yet been found.

These finds in North America have been discredited for various reasons. Some were not made by scientific men accustomed to the closest scrutiny of every detail. Some were reported after a number of years, when the circumstances might not be accurately remembered; while in a number of instances it seems possible that the relics might have been worked into glacial deposits by natural causes from the surface.

Man, we may believe, witnessed the great ice fields of Europe, if not of America, and perhaps appeared on earth under the genial climate of preglacial times. Nothing has yet been found of the line of man's supposed descent from the primates of the early Tertiary, with the possible exception of the Java remains just mentioned. The structures of man's body show that he is not descended from any of the existing genera of apes. And although he may not have been exempt from the law of evolution,—that method of creation which has made all life on earth akin,—yet his appearance was an event which in importance ranks with the advent of life upon the planet, and marks a new manifestation of creative energy upon a higher plane. There now appeared intelligence, reason, a moral nature, and a capacity for self-directed progress such as had never been before on earth.

THE RECENT EPOCH. The Glacial epoch ends with the melting of the ice sheets of North America and Europe, and the replacement of the Pleistocene mammalian fauna by present species. How gradually the one epoch shades into the other is seen in the fact that the glaciers which still linger in Norway and Alaska are the lineal descendants or the renewed appearances of the ice fields of glacial times.

Our science cannot foretell whether all traces of the Great Ice Age are to disappear, and the earth is to enjoy again the genial climate of the Tertiary, or whether the present is an interglacial epoch and the northern lands are comparatively soon again to be wrapped in ice.

NEOLITHIC MAN. The wild Paleolithic men vanished from Europe with the wild beasts which they hunted, and their place was taken by tribes, perhaps from Asia, of a higher culture. The remains of Neolithic man are found, much as are those of the North American Indians, upon or near the surface, in burial mounds, in shell heaps (the refuse heaps of their settlements), in peat bogs, caves, recent flood-plain deposits, and in the beds of lakes near shore where they sometimes built their dwellings upon piles.

The successive stages in European culture are well displayed in the peat bogs of Denmark. The lowest layers contain the polished STONE implements of Neolithic man, along with remains of the SCOTCH FIR. Above are OAK trunks with implements of BRONZE, while the higher layers hold iron weapons and the remains of a BEECH forest.

Neolithic man in Europe had learned to make pottery, to spin and weave linen, to hew timbers and build boats, and to grow wheat and barley. The dog, horse, ox, sheep, goat, and hog had been domesticated, and, as these species are not known to have existed before in Europe, it is a fair inference that they were brought by man from another continent of the Old World. Neolithic man knew nothing of the art of extracting the metals from their ores, nor had he a written language.

The Neolithic stage of culture passes by insensible gradations into that of the age of bronze, and thus into the Recent epoch.

In the Recent epoch the progress of man in language, in social organization, in the arts of life, in morals and religion, has left ample records which are for other sciences than ours to read; here, therefore, geology gives place to archaeology and history.

Our brief study of the outlines of geology has given us, it is hoped, some great and lasting good. To conceive a past so different from the present has stimulated the imagination, and to follow the inferences by which the conclusions of our science have been reached has exercised one of the noblest faculties of the mind,—the reason. We have learned to look on nature in new ways: every landscape, every pebble now has a meaning and tells something of its origin and history, while plants and animals have a closer interest since we have traced the long lines of their descent. The narrow horizons of human life have been broken through, and we have caught glimpses of that immeasurable reach of time in which nebulae and suns and planets run their courses. Moreover, we have learned something of that orderly and world- embracing progress by which the once uninhabitable globe has come to be man's well-appointed home, and life appearing in the lowliest forms has steadily developed higher and still higher types. Seeing this process enter human history and lift our race continually to loftier levels, we find reason to believe that the onward, upward movement of the geological past is the manifestation of the same wise Power which makes for righteousness and good and that this unceasing purpose will still lead on to nobler ends.

THE END