FORMATION. 



PLEISTOCENE EEESH-WATER F0E:\L\TI0X. 



The deposits which are arranged under this head are 

 chiefly found along the valleys of our existing river courses, 

 and generally more or less elevated above the level of the 

 present streams. They contain numerous remains of herbi- 

 ■\irous and carnivorous mammalia ; the Elephant, Ehino- 

 ceros, and Hippopotamus, as well as the Ox, Deer, and 

 Horse, are particularly abundant ; the Bear and Hyaena 

 have also been foimd, but more rarely. Associated with 

 these mammals, are many species (nearly forty) of terres- 

 tial and fresh-water shells, the majority of which are 

 identical vrith. those now liAing in England. Of the four 

 or five that are not British species, two {Paludina margi- 

 nata and Vnio littoralis) are living in France, one {Cyrena 

 trigonula) is said to be the same as a Nile species, and 

 one {Valtata antiqua) has not yet been identified, as also 

 a species of Faludina or Littorina. These deposits consist 

 of layers of Clay, Sand, Loam, and Gravel, varjing very 

 much according to the different localities ; that some of 

 the layers have been quietly deposited is e\"inced from the 

 fact, that fifteen or twenty laminae may be counted in the 

 space of an inch, whilst the gravel beds prove a more 

 irregular movement. 



The excavations in these deposits are chiefly for ex- 

 tracting the valuable brick-earth they contain, and the tine 

 sand which accompanies it. 



The remains found in the Bone Caves of England, &c., 

 probably belong to this period ; the animal remains, more 

 or less entire, are generally mixed with mud, rolled pebbles, 

 and broken fragments, a deposition of Stalagmite covering 

 and forming a compact crust over the whole. Among the 



