Page:Quarterly Journal of the Geological Society of London, vol. 33.djvu/141

Rh LATER TERTIARY GEOLOGY OE EAST ANGLIA. 103 with the Upper Glacial in addition, be identical in character with that drawn through the Kesgrave and Ipswich protrusions from the valley of the Deben to that of the Orwell, which is given in section XX. Speaking of the two outliers of the Contorted Drift at Blaxhall and Kesgrave in the before-mentioned " Introduction," we observed that we thought it most probable that the tablelands dividing the estuaries of East Suffolk from each other, and through w r hich we there gave a line of section (A), were underlain by the Contorted Drift interposed between the Red Crag and the Middle Glacial. With only a knowledge of these two outliers we did not feel justified in actually representing those tablelands as thus underlain, and, subject to such remark, preferred to represent them as occupied by the Middle Glacial only resting upon the Crag. The subsequent discovery, however, of the protrusion at Woodbridge and Hasketon, shown in section XXI., where the Contorted Drift is overlain by the Upper Glacial, and the discovery by Mr. Whitaker of similar protru- sions at Kirton and Trimley, which he communicated to us, leave no doubt on our minds that what we alluded to in our " Introduc- tion " as most probable does in fact exist. The section marked P accompanying the map given in the same " Introduction " should in a similar way be corrected by the inser- tion of a remnant of the Contorted Drift between the Crag and the Middle Glacial, where the height of the hill (about Crane Hall), raises the inference that it is similarly underlain to that on the opposite side of the Orwell, which forms section XX. of the present paper. The outlier at Woodbridge is evidently of great thickness, from the height which it attains above the Bed-Crag level. It consists of silty ash-coloured brick-earth in some places, and of tougher blue brick-earth in others ; and in one excavation these are contorted together, the whole being capped by varying thicknesses of the Upper Glacial. At Kesgrave the outlier must, from its elevation above the Crag-level, be of equal thickness ; and it consists of both light-coloured silty and tough blue brick-earth in different parts of the excavation, while one of the earlier pits now filled with water is in a mass of impure marl, of which many examples occur in the Cromer cliff. The protrusions at Kirton, Trimley, and Ipswich racecourse are in similar brick-earth ; and there is little doubt that they are all exposures of the thicker and least-denuded portions of one continuous formation, out of which the valleys of the East-Suffolk estuaries were interglacially excavated. The line of section XX. is carried through the Kesgrave exposure, from one of the lateral valleys that open out to the main valley of the Deben to the valley of the Orwell, and is susceptible of verification by the numerous open sections which occur along it. If our representation is correct, we have here, as far as regards the Contorted Drift and Middle Glacial, precisely the same kind of section as the North-Norfolk cliff affords ; and a similar section of the same tableland would be afforded by a line carried parallel to, and about eight miles east of No. XX., through the Kirton and