408 Searks V. Woocl,jun. — Sequence of Glacial Beds. 



150 feet deep, whicli then had their inception, and down into which 

 these sands and the subsequent great Chalky Boulder-clay of the 

 Eastern and Midland Counties have gone. 



As this denudation seems to us to have been due, not to an eleva- 

 tion of the Lower Glacial sea-bottom, but to an extension of the 

 land-ice over it, by increment of cold ; and the accumulation of the 

 Middle Glacial sands in these troughs, and generally over the 

 denuded area, to have been permitted by a melting back of this ice 

 (due either to a material increase in subsidence, or else to an aug- 

 mentation of temperature), the deposit of these sands seems to us 

 to mark a great change in the conditions of North-western Europe, 

 which is worthy of a distinctive appellation ; and we cannot, we think, 

 better make this than by preserving the appellation I have for several 

 years past applied to it, of " Mid-glacial," while, at the same time, 

 rejecting any classification based merely upon the intervention of 

 sand or gravel between Boulder-clays. 



Further, I may add, that though we do not venture to assert its 

 absence, yet we cannot at present see anything indicating that the 

 Lower Glacial formation of East Anglia is represented elsewhere in 

 the British Islands ; and although we repudiate the hypothesis of 

 the formation of either the Scotch or the North of England Boulder- 

 clay on a terrestrial surface, believing it to be all of submarine 

 deposit (though produced by land-ice), yet, for the purpose of 

 contrasting the Lower Boulder-clay of Mr. Hull's tabular classifi- 

 cation with the East Anglian beds, let this be admitted ; and 

 then see how the two sides of England would agree. Mr. Hull 

 describes his lower division, that of the Lower Boulder-clay of 

 Scotland, of the North of England, and a large portion of Ireland, 

 as of the period of greatest elevation ; portions of existing seas 

 being then land, and covered by ice; but it is apparent to even 

 a casual observer that the pebbly sands (containing Mya truncata, 

 with its valves united and in vertical position, as it lived), the 

 stratified Till, and overlying contorted drift, which Mr. Harmer 

 and I group together under the term Lower Glacial, and which are 

 exposed in a section of twenty-two miles' length along the Cromer 

 Coast, were there accumulated under the sea; since, where not 

 contorted, even the contorted drift is finely stratified, and con- 

 tains marine shells,^ and where contorted presents clear evidence, 

 from the included masses of marl almost invariably associated 

 with the contortions, of having been a sea-bottom ploughed up by 

 ■grounding bergs, which brought and left in the contorted mud 

 masses of an entirely different material, viz., marl or ground-up 

 chalk. Such evidences appear to Mr. Harmer and myself to negative 

 the possibility of England at that time standing even at so high, far 

 less a higher, level than the present. We obtain evidence, first in 

 the fluvio-marine fauna of the pebbly sand forming the base of the 

 Lower Glacial formation — a fauna showing a very slight departure 

 from that of the Upper Crag beds, on whose denuded surfaces this 



' From the centre of one of these contortions, Mr. Harmer and I took a perfect 

 valve of Tellina Balthica. 



