LATER TERTIARY GEOLOGY OF EAST ANGLIA. 



81 



this crag and associated sands are capped directly by the Middle 

 Glacial in the way shown by section III. 



Fig. 3. — Section III., in a Coprolite-pit by Foxhcdl Hall. (The 

 actual section was in several terraces, which are here omitted. 

 Height of section 45 feet.) 



a. Red Crag unaltered. 



b. Red sands and partly indurated loamy saad horizontally stratified, being a 



altered and restratified. 



c. Middle Glacial, being false-bedded gravel at base and changing upwards into 



stratified gravelly sand. 



From the uniform appearance thus presented by all the numerous 

 sections along the flanks of the Deben, Orwell, and Stour estuaries, 

 not only would it appear as though no formation had intervened 

 between the Red Crag and the Middle Glacial, but also that the 

 valleys of these estuaries had been excavated subsequently to the 

 deposit of the Middle Glacial. The exposures of the Contorted Drift 

 to which we shall have to refer as protruding on the summits of the 

 tablelands dividing these estuaries show, however, as it seems to 

 us, that this was not the case, but that the line of denudation or 

 unconformity separating the Crag from the Middle Glacial in all 

 these sections is due to that general interglacial denudation of the 

 Lower Glacial formation to which the East- Anglian valleys owe their 

 inception. 



We will now take the evidence afforded by the inland sections in 

 illustration of this interglacial denudation and valley-excavation, 

 beginning with the northern extremity of the area mapped by us. 



In the west of Norfolk and Suffolk the chalk floor, though over- 

 spread with Glacial beds, is very irregular ; but with some exceptions 

 this irregularity does not appear to correspond with the existing 

 valleys of drainage. In the central and eastern portions of those 

 counties, however, the Chalk and London clay, wherever exposed, 

 indicate a similar evenness of the floor upon which the Glacial beds 

 repose to that which we have described as being exhibited by the 

 cliff-section of northern Norfolk. 



Q. J. G. S. No. 120. g 



