s PRINCIPAL FEATURES 



gular cracks in the shale oblique cuts in the limestone nearly 

 vertical joints. 



We shall now suppose these strata to be upheaved, by a force 



acting at t so as to come within the power of the waves and 

 currents of the sea, and finally to appear above it. By this 

 elevating force the parts over the ^ will be first brought under 



the corroding agency of the waves ; the cracks being partially 

 opened by the pressure upon the strata, the continuity of these 

 masses of matter is broken, and their power of uniform resist- 

 ance to the water is destroyed ; the weakest parts yield most, 

 and thus before the strata reach the level of the water, their sur- 

 face is channelled, and the land as it emerges above the sea ex- 

 hibits, not a parallel band as A, but a broken ridge as b, w, i, 

 between the points of which the strongest currents flow as re- 

 presented by arrows. 



The rise of the sea bed and the action of the water continuing, 

 the channels for the currents are deepened, the three points of 

 land here indicated are undermined by the wasting of the shale 

 below them, the crown of gritstone falls on all sides, and the 

 appearance, after further continuance of the process, is repre- 

 sented in PI. II. fig. 4, in which (i) is Ingleborough, (w) Whern- 

 side, (b} Barfell ; and the upper ends of Yoredale, Wharfdale, 

 Bibblesdale, Dentdale, Garsdale, and Edendale, begin to appear 

 out of the sea. 



It is needless to follow further the stages by which, under the 

 same conditions of gradual rise of the land and continual battery 

 of the sea on the parts as they successively come near to and 

 reach the surface, the original islands, i, w, b, become united to 

 slopes and ridges, until they constitute merely the culminating 

 points of the country, the conspicuous ornaments of a great and 

 varied physical region. On a surface thus constituted, the 

 atmosphere produces further waste carbonic acid eats away the 

 limestone, moisture softens and crumbles the shale, rains wash 



