GRACE : THE GLACIAL GEOLOGY OF FURNESS. 
405 
valley do not shew drift below 220 feet, and this smaller value corres- 
ponds much better with borings in other places. It is possible, there- 
fore, that the 400 feet record is a mistake, and due to the local name 
for both Yoredale Shales and Boulder Clay being Pinel." 
On Walney Island a boring at Biggar proved Drift to — 150 feet, 
and another at North Scale to — 130 feet. The boring for salt at South 
Walney only reached 89 feet below O.D. before coming to Keuper 
Marls. So that, on the whole, the evidence points to the greatest 
depth of the Sub-Glacial surface being somewhere in the region of 
—200 feet. 
Mr. Lawn, the manager of the Park Mines, has kindly supplied 
Section at Yarlside. 
the accompanying section giving the data obtained by him concerning 
the Sub-Glacial surface in the Yarlside district, east of Furness Abbey. 
The Period of Maximum Glaciation. 
The usual evidence of glaciation reaches to just above the 2000 
feet contour. Higher than this there is an entire absence of smooth 
faces, scratched rocks, boulders, etc. The most probable explanation 
of this is that during the later stages of the Glacial period this area 
would be exposed to severe frost action, and any traces of previous 
glaciation would be removed. This seems more reasonable than that 
it was never subject to the action of moving ice. The highest signs 
of glaciation all shew that during the maximum period the direction 
of ice movement ignored the present valleys, and suggest a flow from 
the north and north-west, much of it, apparently, from the higher 
mountains around Scafell. A col at 2080 feet glaciated from the north- 
east crosses the southern spur of Wetherlam. This is the highest col 
over which we have evidence of moving ice. Further down the slope 
towards Hole Rake are many beautifully glaciated surfaces, all in- 
dicating movement from the same direction. There is also strong 
