39S PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 6, 



seems to have been formed entirely by succulent plants, and to con- 

 tain no wood, whilst the modern peat is full of sticks and boughs. 



I have expressed an opinion in a former paper* that the valleys in 

 this neighbourhood are not due to causes such as we now see in ope- 

 ration, but have been excavated and re-excavated by a powerful and 

 comparatively transient action. I see, then, in the gravel at the base 

 of the Brick-field the debris of a former period of denudation, during 

 which the current swept in an eddy against the hillside forming 

 the ancient cliff, and deposited gravel against its base. This action 

 would leave a hole at a short distance from the bank, such as every 

 angler knows to exist in the elbow of a stream. When the force of 

 the current abated, that hole would become partially filled with mud, 

 and afterwards with a rank growth of marsh-plants, which were con- 

 tinually kept moist and converted into peat by the springs that rose 

 close by. Here the Phytophagous Insects disported themselves, and 

 here the Elephants were lured to their destruction. 



We now come to the consideration of the brick-earth which covers 

 the peat. I have stated that the surface of the peat seems to have 

 been denuded. The denudation has not, however, been of large 

 amount, but has merely produced channels which appear to ran 

 parallel with the old bank, and are filled with clay. In places there 

 is a thin bed of shingle above the peat. The denudation may have 

 been caused by the shifting of the river-course, causing the water to 

 flow at some period or other over the peat; and the brick-earth 

 may be nothing more than the silt deposited by the stream in periods 

 of flood. 



It is also possible that the brick-earth may be an estuarine de- 

 posit, for its height above the sea cannot exceed 60 feet ; the tide 

 now reaches to within less than two miles of the spot. Such a rise 

 in the sea-level would be nothing remarkable in the Post-pliocene 

 period, during which, as is well known, there was in many parts a 

 subsidence of the land to the depth of about 40 feet t. 



Organic Remains. — The facts as yet observed at Lexden do not 

 add to the evidence now relied upon for the association of Man with 

 extinct Mammalia. Mr. Prestwich has indicated the locality as one 

 in which Flint Implements are likely to be found, but they have not 

 yet been observed. There is, however, a bed of gravel still lower 

 than that which is dug ; and it is very probable that, if Flint Imple- 

 ments do occur in the pit, that is their position. 



When I submitted the Insect-remains to Mr. Wollaston for his 

 examination, I requested him particularly to give me his opinion as 

 to the climate which they appeared to indicate ; and also to notice 

 especially whether they agreed specifically with the Coleoptera at 

 present inhabiting Britain. In reply he writes : — " One thing 

 1 feel pretty certain about, namely, that none of those few species, 

 the portions of which I have yet examined, are specifically identical 

 with any of the existing British forms, unless, indeed, it be No. 1 t, 



* Quart. Journ. Geol. Soc. vol. xvii. p. 1. 



f Smith's ' Newer Pliocene Geology,' p. 19. 



X See the specimens, which are in the Society's Museum. 



