﻿66 DR. WOOLACOTT ON THE SUPERFICIAL DEPOSITS, ETC. [Feb. I905, 



ficial deposits of the two northern counties, much detailed field-work 

 must be undertaken before a thorough knowledge of this subject is 

 obtained. 



The rock-surface upon which this clay rests is nearly always 

 smooth, and is in some instances striated, polished, and grooved ; 

 as are also many of the boulders contained therein, more especially 

 those of Bernician Limestone. With one solitary exception, no 

 remains of animal life have been found in it, portions having been 

 washed for micro-organisms without result. It is the true Boulder- 

 Clay, and bears no evidence of having been deposited 

 underwater, being most probably the moraine profonde of 

 an ice-sheet. Except where the solid rock comes to the surface, 

 the whole district is more or less covered by it ; vertically, however, 

 it is limited in height to about 1000 feet. 



(b) The Upper Clay. 



(1) The prismatic clay. — Resting upon the last, or separated 

 from it by deposits of sand, there is, in the less elevated parts of the 

 district, a brownish clay, containing few stones; these are unstriated, 



Fig. 1. — Section from Fulwell Hill to Gleadon Hills. 



VERTICAL SCALE 



F. = 150-foot raised beach, resting against the old sea-cliff at Fulwell. 

 F.W. = Fulwell Waterworks; C. = Cleadon Village, which is built on gravel, 



sand, and sandy clay. 

 O.H.=The raised beach and sea-cliff on Cleadon Hills. 



and smaller and more rounded than those in the stony Boulder-Clay. 

 This brownish clay forms, when present, a layer on tho lower deposit 

 reaching a thickness of 30 feet, and is largely used for brick-making. 

 It has a distinct tendency to vertical prismatic jointing, and was 

 evidently laid down under water. It is derived from the 

 Boulder-Clay, which in some places has been washed up and re- 

 deposited (during the extensive floods that must have occurred on 

 the melting of the ice. at the end of the Glacial Period), in other 

 places has been washed down from the higher grounds by rain; but 

 more generally the prismatic clay has been formed by the sea during 



