1865.] HAEKNESS CUMBERLAND AND WESTMORELAND. 237 



half, the average width being about a mile. Its northern limit is 

 in the township of Melmerby, in Cumberland, and its most southern 

 point is in that of Hilton, in "Westmoreland, this narrow band of 

 Lower Silurian Rocks running from Melmerby through Ousby and 

 Kii'kland in Cumberland, and through Milburn, Knock, Dufton, 

 Murton, and Hilton in Westmoreland, 



The northern boundaries of this Lower Silurian area are the 

 rocks which usually form the base of the Pennine escarpment, 

 namely, the Upper Old Red Sandstone and the Melmerby Scar Lime- 

 stone — the base of the Carboniferous formation in the north of Eng- 

 land, The boundary on the W.S.W. side is more varied : the more 

 southern portion, being the Great Pennine Fault, which brings the 

 Lower Silurian Rocks and the Upper Permian Sandstones in con- 

 tact, is very regular ; but the more northern portion has a very 

 irregular outline, and consists of Upper Old Red Sandstone and 

 Lower Carboniferous Rocks, these having been broken from the 

 Pennine range and thrown down to the west by a fault. These 

 newer Palaeozoic strata come in contact with the Great Pennine 

 Fault on the west, where they have a regular margin ; but on their 

 eastern side, where they join the older Palaeozoic Rocks, their out- 

 line is very irregular. 



The country occupied by the Lower Silurian Rocks in this portion 

 of the north of England presents a very strong contrast to the areas 

 which bound them both on their E.N.E. and W.S.W. sides. To 

 the E.N.E. the bold wall-like limestone-escarpments, the compara- 

 tively unbroken summits, and the easy eastern slopes of the Car- 

 boniferous rocks, exhibit features widely removed from those of the 

 Lower Silurian masses; and the gently undulating surface of the 

 Permian formation to the "W.S.W, presents a still more distinct 

 contour of country. The Lower Silurians of this area are boldly 

 conical in their outline, probably more so than in any other portion 

 of the British isles ; and to such an extent does this conical form 

 prevail that a volcanic origin has been assigned to the rocks — a con- 

 clusion which has been partially borne out by the abundance of 

 porphyries in some of the conical hiUs. 



The peculiar outline of the Lower Silurian rocks can be well 

 seen from the neighbourhood of Appleby, where Knock, Dufton, and 

 Murton pikes, to the east, rise boldly from the gently undulating 

 Permian country at their western bases. It is also distinctly seen 

 from the north and south, in the case of the two former pikes, 

 a deep narrow valley separating them from the Pennine Chain. 



This conical outline was probably the result of rolls in the rocks, 

 and of a fault which runs between the Pennine chain and the Pikes 

 of Knock and Dufton. Subsequent denudation has also greatly mo- 

 dified the original form of this Silurian area. With reference to the 

 latter, the present drainage of the country, which is the only source 

 by which the rocks are exposed in some localities, has cut valleys 

 running nearly east and west, or almost at right angles to the direc- 

 tion of the fault just referred to ; and through these the streams flowing 

 from the steep Pennine escarpment rush westwards -with great 



