98 PEOCEEDIl^GS OF THE GEOLOGICAL SOCIETY. [Jail 9, 



pebbles, ferruginous in places and charged with peroxide of man- 

 ganese (No. 1), is overlain by a sharp sand containing Eocene 

 pebbles (No. 2), and this again by a sandy loam (No. 3), in a trough 

 of which is a layer (No. 4) of rearranged black clay from d o£ 

 section A; above is the surface-soil No. 5. These beds abut sharply 

 on the Woolwich series, and rest on the Thanet sand. Section C, 

 taken 71 paces further to the south, reproduces the beds 1 & 2 of 

 the previous section covered unconformably by a mass of black clay 

 (2) highly contorted and full of black Eocene pebbles. Still further 

 to the south and close to the bridge crossing the tramway is section 

 D, showing 5 feet of gravel of the same character as in B & C, 

 covered conformably by regularly stratified sandy Brick- earth 

 (No. 2), upon the eroded surface of which is a mass of clayey and 

 gravelly " trail," mixed up in a remarkable manner, and containing 

 in its mass large numbers of comminuted Eocene shells derived from 

 e, of section A. A large block of black clay with its angular shape 

 preserved (shown by the thick horizontal lines in the section) was 

 resting in the middle of this bed. Around it passed the highly 

 contorted layers of '' trail," and close to it was a mass of comminuted 

 shells. It corresponds exactly with the black clay (d) of A. 

 Section E, taken at the deepest point in the brick pit, shows a thick- 

 ness of 65 feet of chocolate-coloured and grey loams, with sandy 

 partings and horizontally bedded lenticular patches of gravel con- 

 taining freshwater shells and mammalian bones, and covered 

 by 4 feet of " trail" and one foot of surface soil. The section E, 

 close to the highroad, shows a marked decrease in the thickness of 

 the beds, the Brick-earths at its base being not much more than 12 

 feet thick (No. 1), covered by a foot of false-bedded sand with shells 

 (No. 2), above which is a layer of Brick-earth with calcareous nodules 

 (No. 3). Upon this rests unconformably the " trail " (No. 4), full 

 of Eocene shells, of its usual irregular structure, from 6 to 8 feet 

 thick, and capped by the surface-soil (No. 5). 



The summit of the Brick-earth is about 45 feet above the level of 

 the Thames alluvium. In this pit also we have the threefold nature 

 of the deposit repeated as in the rest. We can not only see the 

 stones and masses of Eocene shells and clay imbedded in the " trail,'' 

 but we can also trace them to the beds from which they were torn. 

 It is altogether impossible that an angular mass of clay could be 

 transported more than 150 yards, preserving its angularity, and de- 

 posited in such a matrix by any other agency than that of ice. It 

 would in a short time have been destroyed by the wash of water 

 under ordinary temperatures. The horizontality of the beds below 

 proves, as in the other cases, that the river which deposited them was 

 not burdened with melting ice. 



e. WiclcJiam. The last of the series of Brick-earths which form 

 the subject of this essay is that about half a mile north of East 

 Wickham Church, on the left side of the road leading from thence to 

 Plamstead. It is extensively used in brickmaking. The section now 

 exposed presents 50 feet of chocolate-coloured loams, devoid of shells 

 and bones, but highly charged with snow-white crystals of carbonate 



