1867.] DAWIIXS LOITER BEICK-EAETHS. 99 



of lime, which form ramifications in every direction. The layer of 

 sand and gravel, whence the remaias in Dr. Spurrell's collection, and 

 in the musenm of the Eoyal Artillery at Woolwich, were obtained, is 

 now worked out. 'Mr. Tlaxman Spurrell, however, who carefully 

 worked at it some years ago, has informed me that it occurred near 

 the bottom of the pit. In the upper part the Brick- earth passes into 

 the tilth without any well-marked surface-soil, excepting that arising 

 from its own atmospheric disintegration, and is at the present time 

 being swept down into the valley below by the rain and frost. It 

 is, indeed, undergoing a process of denudation such as none of the 

 other sections present. "VMiether or no the absence of "trail" can 

 be ascribed to this cause may perhaps be an open question ; but on 

 the whole I am inclined to believe that this pit afi'orded no exception 

 to the rest, and that the "trail" has been removed by the same 

 process that is going on now. 



The excess of carbonate of lime in the strata will probably account 

 for the absence of the usual freshwater shells. The mammalia present 

 no direct evidence as to the relation ia point of time of this to the other 

 Brick-earths, as they consist merely of the Urus, Bison, Horse, Mam- 

 moth, and the tichorhine and leptorhine Rhinoceroses. As, however, 

 it stands at about the same height above the level of the Thames 

 alluvium (from 30 to 40 feet) as the rest, and as no remains of 

 Eeindeer have been found in it, I am inclined to agree with Professor 

 Morris in classifying it with the rest. 



In Dr. Spurrell's collection are two metacarpals of Bison from 

 this pit, with the first phalanges in their natural position, which of 

 course proves that the bones must have been held together by Kga- 

 ments at the time of deposit. 



On the opposite side of the valley is an admirable section of the 

 silted-up bed of an affluent into the stream that once flowed through 

 the vaUey. The Thanet Sand is cut down to the Chalk, and the 

 hollow thus formed is filled with Brick-earth of the same nature as 

 that just described. 



4. Inferences from Sections. — An examination of the above sections 

 (Wickham excepted) proves that the beds which they each represent 

 are of precisely the same geological date, whatever that may be. All 

 of them exhibit the three conditions of deposit in the same order, 

 namely: — Pirst of all a comparatively temperate period, during which 

 the water brought down sand and gravel, and was not burdened with 

 ice-rafts. This is proved by the even bedding and the horizontality of 

 the fluviatile beds, as well as by the regular sorting of the sands and 

 gravels. Then, after an interval of uncertain duration, represented 

 in all the sections by the erosion of the upper fluviatile beds, came 

 a period of intense cold, in which stones, sand, clay, and, indeed, 

 whatever came within the reach of the ice in the neighbourhood, 

 was caught up and deposited in a most confused jumble on its 

 melting ; and, lastly, after this the rain-wash on the top of all radi- 

 cates the obtaining of temperate conditions in the Thames Yalley. 

 The " trail," totally devoid, so far as I know it, of organic remains, 

 may be the ice-wash (if I may coin a term) of the neighbour- 



