466 PLEISTOCENE DEPOSITS. CHAP. 



excavations about Oxford, the sections shew thin interrupted 

 bands of sand, and sandy clay, with small land and fresh-water 

 shells. The pebbles of hard red sandstone are always much 

 rounded, seldom above 4 inches long : those of coral and oolitic 

 limestone are worn away at the edges and surfaces, sometimes as 

 much as 13 inches long; the flints are worn or angular, not ex- 

 ceeding 4 inches in length, and not seldom have many surfaces of 

 fracture, in some degree resembling the more obscure orders of 

 * chipped flints.' These many-surfaced flints are usually of a browner 

 or yellower tint than the others, and must have been subject to 

 some different natural conditions. Small quartz pebbles, white or 

 yellow, one containing tourmaline, occur much rolled. 



The low gravel of the Oxford valley and all its branches, as 

 far as we have ascertained, is wholly of fluviatile or lacustrine 

 arrangement. The action of limited and eddying waters, subject 

 to frequent interruption and change of transporting force, is 

 plainly evidenced by pebble bands, sand patches, and clay bands. 

 The local variations are frequent and sudden, but there is one 

 general character of the deposit : the greater portion of the 

 materials is to be regarded as having been drifted down the 

 valley ; such materials are to be looked for in situ in the country 

 farther northward, by the sides or toward the sources of the actual 

 streams, or else on the hills where quartz, red grit, and other extra- 

 Tamisian stones were left by oceanic waters of early date. 



This indication of the fluviatile accumulation of the gravel is 

 confirmed on a close search into the finer loam and clay bands, 

 sometimes a little peaty, which interlaminate the sands and gravels. 

 In these layers shells of land and fresh-water types occur, in 

 situations 10, 20, and 30 feet above the present floods, and at 

 points removed 100 or 1000 yards beyond their range. Mr. 

 Prestwich and myself made a search of this kind in the large 

 gravel pit close to the Kidlington Station on the Great Western 

 Railway, four miles north of Oxford, and at some other points. 

 We found shells lying in an argillaceous band 3 feet under gravel 

 in the Kidlington pit; and somewhat to our surprise, from damp 

 clay among gravel, in a small excavation by the road-side, on our 

 way homeward from the village of Kidlington, we extracted small 

 specimens of Ancylus fluviatilis. 



Several years previously Mr. H. E. Strickland collected shells 



