﻿546 S. V. Wood, Jim. — Amevican and British 8urf ace- Geology. 



everywhere between Norfolk and the coast of Holland, except for a 

 small space about midway, where the soundings range between 

 twenty-five and twenty-eight fathoms ; and it is possible that this 

 remarkable excavation was accomplished by the glacier tongue which 

 thus passed through the Yare valley. 



Probably the North Sea was deeper throughout the Glacial 

 period than it now is, for it must have been greatly filled with 

 silt since then, like the Yare valley at Yarmouth has been, as well 

 as in parts of it been filled with deposits of Glacial age also ; ' and 

 since then it has, as several things contribute to show, been in its 

 southern part converted into land and again submerged. At the 

 time, however, when the land-ice escaped through these valleys to 

 the sea, even if we assume that the table-lands out of which those 

 valleys are excavated did not stand so high above the sea-level as 

 they now do, we can scarcely, in view of this depth of the valley 

 at Yarmouth, assign a greater depth to the sea in which the eastern 

 side of the inland-ice escaped than 200 feet, — a depth too small, I 

 take it, to engender bergs. 



Towards Belgium it seems to me that this sea continued to shoal, 

 so that, although the South of England and the Boulonnais (and I 

 suspect also a part of Brittany) were covered by it, the shore lay for 

 the most part outside the present coast of Northern France, passing 

 thence across Belgium, where the Ehine and other rivers during 

 the summers of the Glacial period poured over the flats surrounding 

 their embouchures the floods to which the deposits of Limon Hesbayen 

 and Limon des plateaux were due. 



The gravels which over the "West of England represent in my 

 view the Upper Glacial were cut through in excavating the Mickle- 

 ton tunnel at the northern extremity of the Cotteswolds,- where 

 they were found in great thickness at an elevation reaching to 490 

 feet, occupying what was evidently a channel or strait dividing 

 the small island formed by Ebrington Hill from the main island 

 formed by the Cotteswold range at that time. This gravel has 

 been traced by Mr. Lucy up to elevations in the Cotteswold region 

 between 600 and 700 feet ; and it is evident that the washed-out 

 moraine of the glacier which, descending over Lincolnshire, gave 

 rise to the chalky clay, has contributed to the material of this 

 gravel, because there occur in it the large coarse flints so cha- 

 racteristic of that clay, and also pieces of the red chalk, and much 

 more of the hard white chalk of Lincolnshire and Yorkshire.'^ 



^ I learn from M. E. Vandenbroek of Brussels that the Crag to a depth of 415 

 feet has been sunk through at Utrecht, in Holland, under 760 feet of (so-called) 

 Quaternary accumulations, the boring at that depth (1175 feet) being still in sands 

 whose fossils agree with the Coralline Crag, and not those of the earliest of the 

 Belgian Crag-beds. This seems to me to show that the bed of the North Sea, un- 

 disturbed by the Scandinavian glacier-ice, has been tranquilly receiving sedimentary 

 accumulations from the commencement of the Pliocene period up to the conversion 

 of parts of it into land at the close of the Glacial period. 



■ '^ See Gavey in Quart. Journ. Gaol. Soc. vol. ix. p. 295, for fuU description of the 

 Mickleton cutting ; also Hull, in vol. xi. p. 477. 



^ " The Gravels of the Severn, Avon, and Evenlode, and their extension over the 

 Cotteswold Hills," by W. C. Lucy, read April 7th, 1869, before the Cotteswold 

 Club, and printed separately. 



