154 
THE GEOLOGIST. 
the mountain limestone of Low Fnrness^ dipping E.S.E. at higli 
angles_, and disappear in Westmoreland beyond Bannisdale, du- 
ring whicli course tliey rest on the Kirkby Ireleth slate ; but their 
southern boundary can only be understood from the map^ as 
to the west of Windermere they are overlaid by large patches of 
mountain limestone, and in their range eastward are gradually 
covered up uncomformably, and concealed by the Lower Ludlow 
rocks. In some places the similarity of the rocks of the two 
formations, and the absence of fossils in both, makes it difficult 
to determine the boundary between them, the best guide being 
the dip and strike of the rocks. In Mr. Sharpe's first map a 
portion of the Lower Ludlow rocks on the north-east of Kendal 
was erroneously coloured as belonging to the Windermere series ; 
the error was pointed out by Cornelius Nicholson, Esq., of Cowan 
Head, who assisted the author materially in mapping the neigh- 
bourhood of his residence. 
The upper boundary of the Windermere rocks begins on the 
south-west at the lower point of Witherslack, and is marked by a 
great fault which crosses the valley between that hill and '\^Tiit- 
barrow, and appears to pass under the mountain limestone of 
Whitbarrow, then runs north-east through Underbarrow, by the 
Chapel, to Mountjoy : on the west side of this fault the Winder- 
mere rocks form high ridges of hard slaty grits of dark grey co- 
lour, with lighter streaks, dipping N.N.W., while on the east side 
of the fault is a gritty rock of uniform grey colour dipping E. S.E., 
overlaid with beds containing the fossils of the Ludlow beds. 
From Mountjoy the line turns to the north-west, and passes 
round Crook Chapel, whicli stands on a ridge of the Windermere 
grits; at Crock Common it turns to the north-east, and follows 
that direction to near Borrowdale, where the formation is lost, 
being completely hidden by Ludlow rocks, which there rest on 
the Lower Silurians. Crook Common is thrown into great con- 
fusion by the meeting of two lines of elevation, one coinciding 
with the N.N.W. through Carlmel Fell. 
