ff Part of the Yorkshire Coast. 207 



height, these hills correspond nearly with the second range; but 

 they are of a diflferent character from all the rest, being distin- 

 guished by tlie striking similarity of their abrupt northern fronts, 

 forming the same angle with the horizon, and having the same 

 smooth appearance, wearing a covering of short ling and moss, 

 and rarelv presenting atiy broken ground or naked rocks. 



In all these four ridges, as in many other mountainous tracts 

 of Britain, the hills generally rise with a gentle slope from the 

 south, and fall abruptly in steep cliffs towards tlie north. A few 

 of the smaller hills are nearly round, so that they appear like 

 works of art ; as Freeburgh hill, Oliver's mount, Blakey Topping, 

 and some hills on. the west of Lungdale ; most of which have ta- 

 bular summits. Freeburgh and Blakey have indeed been pro- 

 nounced artificial., by authors who had never examined their struc- 

 ture. 



II. Nature and Order of I he Strata. — None of our hills be- 

 long to the primitive class; they are all of the secondary forma- 

 tion, composed of strata, or beds, of various descriptions. There 

 are few places where the stratification can be examined with 

 equal facility; for, besides the opportunities for such investiga- 

 tions afforded by our inland cliffs, and by cuts or deep channels 

 worn by rivers and mountain streams, our bold and lofty shores 

 present complete sections of the strata along the coast. The 

 strata, as in most other bills, are seldom parallel to the horizon, 

 but generally dip towards the south, their inclination correspond- 

 ing with that of the hills themselves, as above described: and 

 they often assume an undulating form, the undulations bearing 

 some proportion to those of the surface, rising in the heights, and 

 falling in the valleys; the strata being thickest and highest in the 

 most elevated situations. 



The great bed of aluminous schistus, or alum-rock, as it is 

 commonly termed, first demands our attention. At Boulby cliffs 

 this immense stratum rises about 450 feet above the level of 't,he 

 sea. In the upper part of the bed, the rock is of a dark slate 

 colour, feels soft and unctuous, like indurated clay ; the lami- 

 nated fracture is smooth and shining, the transverse fracture dull 

 and earthy; it divides horizontally into thin laminae, and, where 

 exposed to the effects of the atmosphere, splits into shiver;or 

 shale, which is blown about by the winds. The natural seariis, 

 or partings, are in an inclined direction, dividing the rock into 

 regular rhomboidal sections, the size of which incre.ases in every 

 successive course froni the top downwards, the texture of the rqek 

 becoming har^der and firmer as we descend. At the depth pf 

 about 2jO feet from the top of the bed, the schistus loses its 

 Amooth unctuous feel, and becomes mixed with a large portion 

 of sand and mica in shining scales. In this part of the bed, about 



60. feet 



