CHAP. VL] RELATIONS OF MID PLEISTOCENE STRATA. 139 



The lower fluviatile strata, 1 to 4, are full of river shells, 

 and bones and teeth of animals, among which those of the 

 mammoth were incredibly abundant, its remains in Sir 

 Antonio Brady's collection alone being estimated by Mr. 

 Woodward to belong to more than one hundred indivi- 

 duals. Above these strata is a layer of clay, brick- 

 earth, and gravel, No. 5, irregular and twisted, and 

 folded in a very remarkable way, somewhat after the 

 manner of the contorted drift on the Norfolk coast above 

 mentioned. It contains pebbles of quartz, Lydian stone, 

 sandstone, angular and waterworn flints, and fragments 

 of grey wethers, one of which weighed 26 pounds. 

 Some of the pebbles are imbedded with their long axes 

 vertical, and therefore could not have been deposited by 

 the action of water. This singular stratum, termed 

 " loess " by Prestwich and " trail " by Fisher, bears unmis- 

 takable signs of having been accumulated by the action of 

 ice, which has caught up the various materials of which 

 it is formed, and deposited them on melting with the 

 utmost irregularity. It proves that the climate at the 

 time was more severe than that which prevailed while 

 the mammaliferous strata below were being formed. 



Above it the surface is composed of the ordinary 

 rainwash of the district, fine red loam, No. 6, which has 

 been accumulated under the climatal conditions of the 

 present time. It contrasts with the bed on which it 

 rests in its homogeneous nature. 



This section is repeated with but little variation at . 

 Grays Thurrock opposite Gravesend, at a distance of 

 about twelve miles. From the lower fluviatile strata 

 of this locality, the most important remains which 

 have been discovered belong to the big-nosed rhinoceros, 

 which frequented the spot in considerable herds, both 



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