KENDALL : THE GLACIATION OF YORKSHIRE. 
307 
shallow waters as the Irish Sea and the Frith of Clyde would be 
unable now to find free flotation for the bergs. The condition of the 
Irish Sea powerfully affected that of Yorkshire, and indeed was one 
of the greatest factors in determining the nature and mode of glacia- 
tion of this county, and we may now consider what would be the 
state of affairs there as the Glacial Period approached its climax. We 
know from the unimpeachable testimony of striae upon rock surfaces 
that there was a general convergence of glaciers of immense size upon 
the northern portion of the Irish Sea from almost every point of 
the compass. The glaciers of Kirkcudbrightshire and adjacent 
Scottish counties poured into it from the northward ,* those of the 
Lake District, radiating from a centre about Great End,t came in 
from the north-east, and others from the Fells of Yorkshire and Lan- 
cashire from the east. X North Wales sent its quota from the south, 
and, finally, the great central basin of Ireland sent a portion of its 
surplus in from the westward. Now, in view of the fact that the 
depth of the Irish Sea rarely exceeds 50 fathoms and that glacial 
stria3 are found on hills quite close to the coast at altitudes exceed- 
ing 1,000 feet above sea level, it will to many people not be surprising 
to find that this great influx of ice completely displaced the sea and 
converted the area into a huge ice-basin, in many particulars resem- 
bling that of Greenland. Of the depth of the ice we have a criterion, 
though an imperfect one, furnished by the fact that the highest point 
of the Isle of Man (Snaefell, 2,034 feet) was completely buried beneath 
the ice, and, along with its companion hills, was glaciated from top 
to bottom. Under these conditions new directions of flow would be 
taken, some of which might have been predicted a priori had we not 
previously determined them a posteriori. Three obvious outlets 
from the Irish Sea suggest themselves : one through the St. George's 
Channel between the Wicklow Mountains and the Snowdonian 
massif ; one by way of the broad low valley between the Pennine 
Chain and the Welsh hills ; and a third through the North Channel 
between the Antrim Coast and the Rinns of Galloway. The first and 
second ot these routes we find by the evidence of stria?, boulder- 
* Geol. Surv. Mem. f Ward, Q. J. G. S., vol. xxxi. 
X Tiddeman, Q. J. G. S., vol. xxviii. ; Goodchild, op. cit., vol. xxx. 
