From a large number of such discoveries it is conclusively shown that, after all, Scotland was smothered under one enormous glacier, a change of climate occurred, and the ice melted away. Then Scotland enjoyed a climate capable of nourishing sufficient vegetation to induce mammoths, Irish deer, horses, and great oxen to occupy the land. But the upper bowlder clay no less conclusively shows that once more the climate became cold, and ice overflowed all the lowlands and buried under a new accumulation of bowlder clay such parts of the old land surface as it did not erode. Substantially the same set of changes are observed in English and German geology.28 Having thus given an outline of the climatic changes which took place in Europe during the Glacial Age, and the grounds on which these strange conclusions rest, we must now turn our attention to the appearance of man. The uncertainties which hung over his presence in the earlier periods, spoken of in the former chapter, do not apply to the proofs of his presence during this age, though it is far from settled at what particular portion of the Glacial Age he came into Europe. We must remember we are to investigate the past, and to awaken an interest in the history of a people who trod this earth in ages long ago. The evidence on which we establish a history of the early tribes of Europe is necessarily fragmentary, but still a portion here and a piece there are found to form one whole, and enable us to form quite a vivid conception of manners and times now very far remote. It is not claimed that we have surmounted every difficulty—on the contrary, there is yet much to be deciphered; but, in some respects, we are now better acquainted with these shadowy tribes of early times than with those whose history has been recorded by the historian’s facile pen. He has given us a record of blood. He acquaints us with the march of vast armies, tells us of pillaged cities, and gives us the names of a long roll of titled kings; but, unfortunately, we know little of the home life, the occupation, or of those little things which make up the culture of a people. But the knowledge of primitive tribes, gathered from the scanty remains of their implements, from a thorough exploration of their cavern homes, has made us acquainted with much of their home life and surroundings: and we are not entirely ignorant as to such topics as their trade, government, and religion. We must not forget that this is a knowledge of tribes and peoples who lived here in times immeasurably ancient as compared with those in existence at the very dawn of history.