“The East Anglian Glacier.—The influence of the Scandinavian ice is clearly seen in the fact that the entire ice-movement down the east coast south of Bridlington was all from the seaward. Clays, sands, and gravels, the products of a continuous mass of land-ice coming from the northeast are spread over the whole country, from the Trent to the high grounds on the north of London overlooking the Thames.
“The line of extreme extension of these drift-deposits runs from Finchley (near London), in the south across Hertfordshire, through Cambridgeshire, with outlying patches at Gogmagog and near Buckingham, and northwestward over a large portion of Leicestershire into the upper waters of the Trent, embracing the elevated region of Palæozoic rocks at Charnwood Forest, near Leicester.
“Reserving the consideration of the very involved questions connected with the drifts of the upper part of the Trent Valley, I may pass on to join the phenomena of the southeastern counties with those at Flamborough Head. From Nottinghamshire the limits of the drift of the East Anglian Glacier seem to run in a direction nearly due west to east, for the great oolitic escarpment upon which Lincoln Cathedral is built is absolutely driftless to the northward of the breach about Sleaford. However, along the western flank of the oolitic range true boulder-clay occurs, bordering and doubtless underlying the great fen-tract of mid-Lincolnshire; and the great Lincolnshire Wolds appear to have been completely whelmed beneath the ice.
“The most remarkable of the deposits in this area is the Great Chalky Boulder-Clay, which consists of clay containing much ground-up chalk, and literally packed with well-striated boulders of chalk of all sizes, from minute pebbles up to blocks a foot or more in diameter. Associated with them are boulders of various foreign rocks, and many flints in a remarkably fresh condition, and still retaining the characteristic white coat, except where partially removed by glacial attrition.
“One of the perplexing features of the glacial phenomena in the eastern counties of England is the extension of true chalky boulder-clay to the north London heights at Finchley and elsewhere; for only the faintest traces are to be found in the gravel deposits of the Thames Valley of any wash from such a deposit, or from a glacier carrying such materials.
“It has been suggested that the deposit may have been laid down in an extra-morainic lake, or in an extension of the North. Sea, but these suggestions leave the difficulty just where it was. If a lake or sea could exist without shores, a glacier-stream might equally dispense with banks. Within the area of glaciation, defined above, abundant evidence of the action of land-ice is obtainable, though striated surfaces are extremely rare—a fact attributable to the softness of the chalk and clays which occupy almost the whole area. Well-striated surfaces are found on the harder rocks, as, for example, on the oolitic limestone at Dunston, near Lincoln.
“Mr. Skertchly has remarked that the proofs of the action of land-ice are irrefragable. The Great Chalky Boulder-Clay covers an area of 3,000 square miles, and attains an altitude of 500 feet above the sea-level, thus bespeaking, if the product of icebergs, ‘an extensive gathering-ground of chalk, having an elevation of more than 500 feet. But where is it? Certainly not in Western Europe, for the chalk does not attain so great an elevation except in a few isolated spots.’[BR]
[BR] Geikie’s Great Ice Age, p. 360.