562 



PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Juiie 20, 



tion — frost and rain, wind, earthworms, and the growth of herbage — ■ 

 are causes in operation at the present day ; and therefore it might be 

 expected that the warp is the latest geological formation. Yet I 

 believe that conclusion would be incorrect. 



It is evident that it has been formed for a long period, because the 

 layer of pebbles usually seen at its base vrill be frequently found to 

 have descended to the depth of a foot or more over the mouth of any 

 subjacent pipe which may happen to have been formed in a calcareous 

 rock. In a similar manner channels of slight subterranean drainage 

 will be found to deflect the layer. These effects must have taken some 

 time. But a more definite measure of its age was first noticed by 

 Mr. Trimmer in his paper "On the Soils of Kent"*. He there 

 states that he had found " in the neighbourhood of Taversham, he- 

 low the level of high-water mark, lacustrine and fluviatile deposits 

 covered by non-fossHiferous deposits analogous to that of the erratic 

 warp of Norfolk." I have noticed myself the passage of the warp 

 below the level of high-water mark in the estuary of the Colne. 

 About two miles below Colchester the outline of the rising ground, 

 marked by the unbroken continuation of the warp, passes beneath 

 the silt of the estuary. The surface of the silt, now reclaimed for 



Fig. 9.- 



Section in a ditch on Tendring Hundred Railway j 

 near Colchester. 



a. Warp passing beneath (6) Silt of the estuary. c. London clay. 



Fig. 10. — Railway Viaduct over Alresford Creek, Essex. 



X 300 ft X 400 ft. 



Marsh. 



X 



Marsh. 



* Low- water mark. 



a. Estuarine mud of the present marsh 



b. " Scrobicularia"-clsij. 



c. Warp. 



t High-water mark. 



, d. Probably London Clay. 



e. Gravel. 



/. Sandy gravel. 



? The line of section on the south side does not meet the upland again, but after 

 crossing some marshy ground, runs into the estuary of the Colne. 

 Specimens from this section are deposited in the Society's Museum. 



meadowland, must be about 6 feet below high-water mark. The 

 section was seen in a ditch by the side of the Tendring Hundred 

 E-ailway. 



Another instance of the same kind in the same neighbourhood 

 was disclosed in the sinking of the cyHnders on which the rails are 



* Quart. Journ. Geol. Soc. vjI. vii. p. 36. 



