112 



outcrop of the latter rock, beneath the sea, being some distance 

 outside the present shore. But the depth at which the Permian 

 rocks lie beneath the level of the sea^prevents them from exercising 

 any influence whatever on the shape of the coast line, and conse- 

 quently from affording any indications as to their respective 

 boundaries. If we compare the prominence of the coast-Une 

 close to Maryport with its recession in Allonby Bay, we see the 

 difference between the effect of marine denudation on cliffs the 

 base of which, at least, is red sandstone, and cliffs wholly composed 

 of glacial drift. But in and north of Allonby Bay the coast 

 features are wholly drift features, and nowhere allow us to compare 

 the effects of the sea on St. Bees Sandstone and on Gypseous 

 Shales. 



So much for the effects of the drift covering as a hindrance to 

 knowledge of the rocks below. But a more deep-seated hindrance 

 lies in the decided unconformity of the Permian rocks to the 

 underlying Carboniferous beds. This unconformity impHes that 

 before the deposition of the Permians, the Carboniferous rocks 

 had been elevated and had become land. That this elevation 

 had been unequal in different places, and that in consequence 

 of this inequality the rocks had suffered in very different 

 degrees locally, both from the action of the sea during elevation, 

 and of rain and rivers since the tract became dry land. At a 

 subsequent period the Carboniferous area became subject to a 

 movement of depression, and the Permian rocks were deposited 

 upon it. Thus the relations of these two formations to each other 

 are necessarily very different from those which would have existed 

 had they been deposited in a slowly- and continuously subsiding 

 area, no movement of upheaval having intervened. For instead 

 of the base of the Permian series being always on a particular 

 geological horizon, it may rest at one place on the highest of the 

 Carboniferous beds, at another on the lowest. In other words — under 

 the St. Bees Sandstone at Bowness, for example, may be rocks of 

 Carboniferous Limestone age; under Kelsick Moss Coal Measures, 

 or beds of Yoredale age — or just the reverse may occur. And 

 besides this uncertainty arising from the unconformity between 



