536 Geological Society : Mr. D. Sharpe on the 



beds dip south-east by south 65°, and the cleavage dips in the same 

 direction 80° ; from here it crosses into High Borrowdale half a mile 

 above High House, dipping south-east by south 50° ; a fault down 

 this valley throws the bed below High House on the east side of the 

 valley : in the next Fells it is much concealed by the vegetation, 

 but it is seen at a cutting of the road from Shap to Kendal on Hurd's 

 Brow, between the ninth and tenth milestone, dipping south-east 

 75°, and the cleavage dipping north-west 85°. Near the Borrow 

 the beds are thrown into several anticlinal ridges bearing north-east, 

 by faults which disturb the cleavage planes as well as the bedding 

 of the rock : this slate has also been worked in the upper part of 

 Bretherdale. The boundary thus laid down nearly corresponds with 

 that given in the new edition of Mr. Greenough's map. 



The lowest beds of the slate in High Borrowdale are calcareous, 

 and may perhaps represent the Blawith limestone, which has not 

 been found in conjunction with the slate eastward of Blawith. 



In High Furness, the district of Lancashire consisting of Lower 

 Silurian rocks, the principal valleys run from south-west to north- 

 east, parallel to the strike of the beds, each ridge of hills repre- 

 senting the outcrop of a particular bed : this is not the case with 

 the same formation in Westmoreland, where the valleys of Coniston 

 Water, Esthwaite, Windermere, Troutbuk, Kentmere, Long Sled- 

 dale, Bannisdale, High Borrowdale, and Brethesdale, all follow great 

 faults across the strike of the stratification : these faults are con- 

 tinued through the Windermere rocks, and sometimes into the Lower 

 Ludlow rocks, but are lost before entering the Upper Ludlows. 



It is in High Furness that the Lower Silurian formation is best ex- 

 posed to observation, and has a greater thickness than in Westmore- 

 land, the beds gradually diminishing in their course eastward. In 

 the same district of Lancashire the slaty character of the rocks is 

 more developed than we find it in Westmoreland ; it is especially 

 between Coniston, Old Mere and Kirkby Ireleth, that the crystal- 

 lizing agency which has changed the rocks into slate has acted most 

 powerfully, many beds in that district supplying 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 formation 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 geographical boundaries. 

 They rise, near Ulverston, from below the mountain limestone of 



