GEOLOGICAL SOCIETY OF LONDON. 
153 
Lower Silurian rocks^ the principal valleys run from soutli-west 
to nortli-east^ parallel to the strike of the beds, each ridge of 
hills representing the ontcrop of a particular bed : this is not the 
case with the same formation in Westmoreland^ where the valleys 
of Coniston Water, Esthwaite, Windermere, Troutbulk, Kent- 
mere, Long Sleddale, Bannisdale, High Borrowdale, and Brethes- 
dale, all follow great faults across the strike of the stratification : 
these faults are continued through the Windermere rocks, and 
sometimes into the Lower Ludlo^v rocks, but are lost before enter- 
ing the Upper Ludlows. 
It is in High Furness that the Lower Silurian formation is 
best exposed to observation, and has a greater thickness than in 
Westmoreland, the beds gradually diminishing in their course 
eastward. In the same district of Lancashire the slaty character 
of the rocks is more developed than w^e find it in Westmoreland ; 
it is especially between Coniston, Old Mere and Kirkby Ireleth, 
that the crystallizing agency which has changed the rocks into 
slate has acted most powerfully, many beds in that district sup- 
plying good slate, which will hardly split up at all elsewhere. 
From the prevailing parallelism long known to exist between 
the planes of slaty cleavage over considerable areas, Mr. Sharpe 
considers it nearly certain that these planes had a uniform 
direction in each district, and that the cases of exceptions which 
are found, are due to disturbing forces acting after the cessation 
of the cleavage action. In the district under consideration the 
mean dip of the cleavage planes is considered to be S.S.E. 70'^, 
and the cleavage action is thought to have ceased before the for- 
mation of the Upper Ludlow rocks. 
Windermere Rocks. — The beds formerly classed by the author 
as the lowest division of this series are now placed in the Lower 
Silurian formation, and the middle and upper divisions are 
thrown together, for want of any distinct line of division between 
them, and some considerable corrections are made in their geo- 
graphical boundaries. They rise, near Ulverston^ from below 
VOL. II.-— NO. XVII. Q 
