ANCIENT GLACIERS IN EASTERN HEMISPHERE. 147 



Moor, near Toclmorden (1,419 feet), boulder-clay has been 

 found containing erratics belonging to this dispersion ; 

 while in the gorge of the Yorkshire Calder, which flows 

 along the eastern side of the same hill, not a vestige of 

 such a deposit is to be found, saving a few erratic pebbles 

 at a distance of eight or ten miles, which were probably 

 carried down by flood- wash from the edge of the ice. 



" From this point the limits of the ice may be traced 

 along the flanks of the Pennine chain at an average alti- 

 tude of about 1,100 feet. 



" At one place the erratics can be traced to a position 

 which would indicate the formation of an extra-morainic 

 lake having its head at a col about 1,000 feet above sea- 

 level, separating it from the valley of an eastward flow- 

 ing stream, the Wye, about twelve miles down which a 

 few granite blocks have been found. Other extra-morainic 

 lakes must have been formed, but very little information 

 has been collected regarding them. The Irish Sea Glacier 

 can be shown to have spread across the whole country 

 to the westward of the line I have traced, and beyond the 

 estuary of the Dee. 



" I may now follow its boundaries on the "Welsh coast, 

 and pursue the line to the final melting-place of the glacier. 

 From the Little Orme's Head the line of confluence with 

 the native ice is pretty clearly defined. It runs in, per- 

 haps, half a mile from the shore, until the broad low tract 

 of the Vale of Clwyd is reached. Here the northern ice 

 obtained a more complete mastery, and pushed in even 

 as far as Denbigh. This extreme limit was probably at- 

 tained as a mere temporary episode. Horizontal strise on 

 a vertical face of limestone on the crags dominating the 

 mouth of the vale on the eastern side attest beyond dis- 

 pute the action of a mass of land-ice moving in from the 

 north. 



" I may here remark, that in this district the deposits 

 furnish a very complete record of the events of the Glacial 



