1867.] 



DAWKINS LOWER BRICK-EARTHS. 



97 



of different circum stances of deposit, is observable. Its discrepancy 

 with the admirable section given in 1838 by Professor Morris may 

 be explained by the variability of the beds in the enormous pit. 

 The top of the Brick-earth is about 50 feet above the alluvium of the 

 Thames. 



^. Erith. The second brick-pit is situated on the right-hand 

 side of the road from Erith to Crayford, immediately after it has 

 crossed the North Kent Railway, and about one mile from that at 

 Crayford. It is peculiarly interesting as affording a section from 

 the top of the Woolwich beds down to the Chalk, as weU as proving 

 that the Brick-earth rests on the edges of the Eocene strata, and in 

 a hollow excavated in the Chalk. In the diagram (fig. 4) I have not 

 attempted to give the horizontal distribution of the strata, but merely 

 the vertical thickness. 



Fig. 4. — Section at Whitens Pit, Erith. 



Vertical scale ^ in. to a foot. Horizontal extent not represented. 



a. Chalk with flints, b. Thanet Sand, with a layer of tabular flints at the base. 

 c. Woolwich sand. d. Stiff black clay. e. Lenticular mass of shells. 

 /. Bed of black Eocene flints, with quartz pebbles, g. Surface-soil. 



At the base both of the Eocene beds and of the Brick-earths lies the 

 Chalk with flints, nearly horizontal, and quarried to a depth of more 

 than 100 feet (a of section A). Above this is the Thanet Sand with 

 the usual layer of tabular flints- at its base (h of the same section), 

 and with a dip of 10° to the IS'.IN'.'W. It is overlain by the Woolwich 

 sand, reddish-brown in colour (c), containing a bed of stone, and in 

 its upper part consisting of sandy and loamy layers with Septaria 

 and many shells, on which rests conformably a stiff black clay with 

 few shells {d). Above this is a lenticular mass of Eocene shells, 

 very irregular (e), capped by a bed of black Eocene flints with 

 a few quartz pebbles (/), at the top of which is the surface-soil {g'), 

 a and e are peculiarly interesting as presenting the beds, in situ, 

 whence some of the materials of the " Trail " covering the Brick-earth 

 were derived. 



At 50 paces to the south the gravel-series comes suddenly in, at 

 section B, where 14 feet of regularly stratified sandy gravel, com- 

 posed of Eocene flints, angular and waterworn flints, and quartz 



