XVIIL BRENTFORD. 469 



gravel, abounding in flints as might be expected, was accumulated 

 in irregular hollows of the chalk; at Maidenhead spread out in 

 broad plains and rudely parallel layers, on the wasted and pitted 

 surface of the chalk. 



At Brentford the pleistocene deposits above the London clay 

 have been successfully examined, long since by Trimmer 6 , and 

 twenty years since by Morris f . The memoir of the latter geologist, 

 which fills up the lacuna between the Oxford sections and those 

 below the metropolis, contains the following section : 



ft. in. 

 8. Vegetable mould ...... . ..... . .10 



7. Brick earth, a fine brownish loam . . . . . . .40 



6. Fine sand, mostly stratified and obliquely laminated, with wavy 



and irregular veins of small gravel . . . . . .60 



5. Sand with light-coloured clay and irregular gravel, containing 



bones (average) . . " . . . . . .07 



4. Ferruginous gravel and sand, with patches of clay . . .10 

 3. Clayey sand and sandy gravel, with occasional large flintstones, 



partly ferruginous at the upper part, containing shells and 



bones . . . . . . . . . I o to 2 o 



2. Ferruginous sand and gravel .-.06 



i. Light clayey sand and ferruginous gravel, with boulders of quartz 



granite rock with ammonites, &c., also bones of ox, deer, &c. 6 to 7 o 



London clay below. 



This section represents the main features of the Yarnton pits, 

 with the layer of northern and other boulders at the base, above 

 which were found most of the mammoth remains. The shells 

 found by Professor Morris and Mr. Lay ton in the bed here marked 

 3, were the following : 



Bithynia impura. 

 Succinea amphibia. 

 Valvata piscinalis. 

 Limnaea auricularis. 



Limnaea stagnalis. 

 Pisidium amnicum. 

 Cyclas cornea. 

 Anodon anatinus. 



These land and fluviatile shells support the conclusion that the 

 deposit is due to fluviatile action ' far more deep and extensive than 

 that of the present river.' 



The mammalian remains consist of 



Bos longifrons. 

 Cervus elaphus. 

 Cervus tarandus. 

 Felis spelsea. 



Elephas primigenius. 

 Rhinoceros tichorhinus. 

 Hippopotamus major. 

 Bison priscus. 



e Phil. Trans. 1813. f Geol. Soc. Journ. 1850. 



