GEOLOGY. 9 



mixed up with the limestone. In Penyghent and Ingle- 

 borough its upper surface is 1,300 feet, and beneath Great 

 Whernside it is 1,400 feet above the sea-level. At the head of 

 the Ribble it has sunk to 1,000 feet, and between this point 

 and the south side of Yoredale opposite Hawes it declines 150 

 feet more. Altogether in Yoredale about 240 feet of its upper 

 portion is exposed. It fills up the lower part of the valley from 

 the Hawes neighbourhood as far east as Redmire, a distance of 

 twelve miles. Its limestones form the long low terrace that 

 borders the road between Askrigg and Carperby, the falls about 

 the village of Gayle, the picturesque rapids of Aysgarth, and 

 they may also be seen exposed round the sides of Seamer 

 Water. Here the interpolations in the limestone are princip- 

 ally argillaceous, and may be best seen about Askrigg and 

 above Aysgarth Bridge, and bear altogether to the limestone a 

 proportion of about two to three. From Great Whernside to 

 Aysgarth it declines 700 feet in eight miles. On the north side 

 of Yoredale opposite Hawes we have the upper surface of this 

 lower limestone at about 800 feet above the sea level, and in 

 Swaledale, at about the same height, a small portion of the 

 upper part is exposed to view in the neighbourhood of Muker. 

 From this point northward it is not anywhere to be seen till we 

 reach Upper Teesdale. In the Mickle Fell tract the upper beds 

 may be seen immediately above the Basalt. Here the upper 

 band of limestone is from 25 to 50 feet in thickness, and is 

 known by the name of Tyne bottom limestone. In Cronkley 

 Fell it reaches an elevation of 1,750 feet, but from this point it 

 is much depressed by dislocations both towards the north and 

 east, and south-east of the great fault which ranges along Lune- 

 dale it is lost altogether. By proximity with or contiguity 

 to the Basalt, the various strata become much changed in 

 character, the shales prismatised, both the sandstones and shales 

 bleached and rendered brittle, and the normally compact cal- 

 careous beds which immediately overlie the basalt are me- 

 tamorphosed, as in Cronkley Fell, into a loosely granular 



Jan. t888. 



