3 9 ^ Glacial Epoch. 



sheet, when it so happened that the cold of that region 

 became most intense. 



Assuming this theory to be true, the old glacier 

 must have reached the plateau of Romford that over- 

 looks the valley of the Thames, and the low country on 

 the coast of Essex, near Southend. One serious difficulty 

 to its acceptance occurs in the fact, that on the coast-cliff 

 near Lowestoft there are beds of Boulder-clay which 

 overlie thick strata of soft false-bedded sands with gravel, 

 and these sands lie apparently quite conformably and 

 undisturbed beneath the Boulder-clay. If the latter 

 was the ground-moraine that underlay a heavy glacier 

 pressing southward, it is hard to understand why the 

 sands show no signs of pressure and glacial erosion. 

 Neither is it necessary to suppose that glaciers are 

 always needed for the production of ice-polished sur- 

 faces of rock and for the making of Boulder-clay, for, 

 as shown by Professor H. Youle Hind, the formation of 

 both on a large scale is now and has been for long in 

 progress on the north-east coast of Labrador, through 

 the agency of ' Pan ice/ which ' is derived from Bay 

 ice, floes, and coast ice, varying from five to ten or twelve 

 feet in thickness, all of which are broken up during 

 spring storms.* This broken ice is pressed on the coast by 

 winds, 'and being pushed by the unfailing Arctic 

 current, which brings down a constant supply of floe- 

 ice, the pans rise over all the low-lying parts of the 

 islands, grinding and polishing exposed shores,' and 

 removing ' with irresistible force every obstacle which 

 opposes their force . . . and the masses pushed or 

 torn from those surfaces . . . are urged into the sea 

 and rounded into boulder forms by the rasping and 

 polishing pans.' Here, too, goes on the process of 

 manufacturing Boulder-clay, for the deep hollows and 



