Ch. X.] MAX COEVAL WITH EXTINCT MAMMALIA. H5 



preseut outline of the surface. Since those deposits originated, 

 changes of considerable magnitude have been effected in the depth and 

 width of many valleys, also in the direction of the superficial and sub- 

 terranean drainage, and, as is manifest near the sea-coast, in the relative 

 position of land and water. In the annexed diagram (fig. 106), an 

 ideal section is given, illustrating the different position which the 

 recent and post-pliocene alluvial deposits occupy in many European 



The peat No. 1 has been found in a low part of the modern allu- 

 vial plain, in parts of which gravel No. 2 of the recent period is seen. 

 Over this gravel the loam or fine sediment 2' has in many places been 

 deposited by the river during floods which covered nearly the whole 

 alluvial plain. 



No. 3 represents an older alluvium, composed of sand and gravel, 

 formed before the valley had been excavated to its present depth. It 

 contains the remains of fluviatile shells of living species associated 

 with the bones of mammalia, in part of recent and in part of extinct 

 species. Among the latter, the mammoth (E. primigenius) and 

 Siberian rhinoceros (JR. tichorhinus) are the most common in Europe. 

 No. 3' is a remnant of the loam or brick earth by which No. 3 was 

 overspread. No. 4 is a still older and more elevated terrace, similar 

 in its composition and organic remains to No. 3, and covered in like 

 manner with its inundation mud, 4'. Often there is only one of 

 these valley gravels of older date, and occasionally there are more 

 than two, marking as many successive stages, in the excavation of 

 the valley. They usually occur at heights varying from 10 to 100 

 feet, sometimes on the right and sometimes on the left side of the 

 existing river-plain, but rarely in great strength on exactly opposite 

 sides of the valley. 



Among the genera of extinct quadrupeds most frequently met with 

 in England, France, Germany, and other parts of Europe, are fflephas, 

 Rhinoceros, Hippopotamus, Equus, Megaceros, Ursus, Felis, and 

 Hyarna. In the peat No. 1 (fig. 106) and in the more modern gravel 

 and silt (No. 2), works of art of the ages of iron and bronze, and of 

 what we may call the " later stone period," already described, are met 

 -xvith. In the more ancient gravels, 3 and 4 (fig. 106), there have 

 been found of late years in several valleys in France and England, as, 

 for example, in those of the Seine and Somme, and of the Thames, and 

 Ouse, near Bedford, stone implements of a rude type, showing that 

 man coexisted in those districts with the elephant and other extinct 

 quadrupeds of the genera above enumerated. 



Several geologists had come to the conclusion, about the close of 

 the last and beginning of the present century, that certain human 

 remains embedded in the mud and breccia of caves were as old as the 

 extinct mammalia with which they were associated. But the evidence 

 of such high antiquity was not generally received as satisfactory, see- 

 ing that so many caves had been inhabited by a succession of tenants, 



