Finally, we have to consider the age of the deposits. This is a question that can be answered only by geologists, and we may be sure that more than ordinary attention has been bestowed upon them. The remains of many animals characteristic of the Glacial Age were found in the beds at Abbeville. These include those of the elephants, rhinoceros, hyenas, cave-bear, and cave-lion.34 In the formation of these gravel beds, ice has undoubtedly played quite an important part. Bowlders that could have got there only by the aid of ice, are found in several localities. Evidence gathered from a great many different sources all establish the fact that these gravels date as far back as the close of the Glacial Age at least, and there are some reasons for supposing them to be interglacial. We can easily see that the melting away of the immense glaciers that we have been describing would produce vast floods in the rivers, and it is perhaps owing to the presence of such swollen rivers that are due the great beds of surface soil, called loam or loess, found in all the river valleys of France and Germany.35 These deposits frequently overlie the gravel beds. They are then of a later date than the beds in which are found such convincing proofs of the presence of man, and if they themselves date from the close of the Glacial Age, it is no longer a question whether the gravel beds themselves belong to that age. Thus we see that we can no longer escape the conclusions of Boucher DePerthes. The discovery of rudely worked flints in the drift of the Somme River thus establishes the fact that some time during the Glacial Age, man in a Paleolithic state lived in France. Geological terms convey to us no definite ideas as to the lapse of time, and we have an instinctive desire to substitute for them some term of years. In most cases this is impossible, as we have no means to measure the flight of past time, nor are we yet prepared to discuss the question of time, since to do so we must learn a great deal more about the cause of the Glacial Age. We might, however, cite statements which can not fail to impress us with the fact that a great extent of time has passed.