Page:Quarterly Journal of the Geological Society of London, vol. 33.djvu/119

Rh 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