546 S. V. Wood,jun. — American and British Surface-Geology. 
everywbere between Norfolk and the coast of Holland, except for a 
small space about midway, where the soundings ränge between 
twenty-five and twenty-eigbt fatboms ; and it is possible tkat tbis 
remarkable excavation was accomplished by the glacier tongue which 
thus passed through tbe Yare valley. 
Probably tbe North Sea was deeper tbrougbout the Glacial 
period than it now is, for it must have been greatly filled witb 
silt since then, like tbe Yare valley at Yarmouth has been, as well 
as in parts of it been filled witb deposits of Glacial age also ; 1 and 
since then it bas, as several tbings contribute to sbow, been in its 
southem 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 Bhine 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 Miekle- 
ton tunnel at the northern extremity of the Cotteswolds, 2 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 ränge 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 
rnore of the hard white chalk of Lincolnshire and Yorkshire. 3 
1 I learn from M. E. Yandenbroek of Brussels that the Crag to a depth of 415 
feet has been sunk through at Utrecht, in Holland, undtr 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 Xorth Sea, un- 
disturbed by the Scandinavian glacier-ice, has been tranquilly receiving sedimentär}- 
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. 
J See Gavey in Quart. Journ. Geol. Soc. vol. ix. p. 295, for full description of the 
Mickleton eutting ; also Hüll, in vol. xi. p. 477. 
3 “ The Gravels of the Severn, Avon, and Evenlode, and their extension over the 
Cotteswold Hills,” by W. C. Lucy, read April 7th, 1869, betöre the Cotteswold 
Club, and printed separately. 
