A Rock of Unknown Origin from Glacial Gravel at Ipswich

Abstract

A LITTLE time ago I found, in the sub-Chalky Boulder Clay glacial gravel, exposed in the brickfield of Messrs. A. Bolton and Co., Ltd., to the north of Ipswich, an erratic of unusual and arresting appearance. The gravel in which the specimen was embedded is that which, in my opinion, was laid down in the interval of time between the deposition of the Kimmeridgian Chalky Boulder Clay and that of the Upper Chalky Boulder Clay of East Anglia. As I had never before seen a rock in the Ipswich area of the type discovered, I submitted it to Prof. P. G. H. Boswell, of the University of Liverpool, and to Dr. Herbert H. Thomas, of the Geological Survey, for investigation. Both these experts, though giving me valuable information upon the nature of the erratic, were unable to inform me as to its probable source of origin, and Dr. Thomas, suggesting that this source might be in some area of old rocks, such as Scandinavia, advised me to submit the specimen to Prof. Victor Goldschmidt, of Oslo. This I have now done, and with Prof. Goldschmidt's permission, I give below the result of his examination of the rock.