172 baker's north YORKSHIRE. 



we have the beds of the Millstone Grit series forming the cap- 

 rock of many of the summits, and reaching their greatest thick- 

 ness, that is to say, with most of the bands not disintegrated 

 away, in Great Whernside, Penhill and Lovely Seat. 



East of Leyburn the moorlands cease, and the district which 

 the Yore drains on the north becomes still narrower than before. 

 On the south side of the river we have now an undulated m.oor- 

 land gritstone country, sloping suddenly towards the east, and 

 penetrated by a eugeogenous dale, the stream of which runs 

 from west to east and has numerous branches. It is about ten 

 miles in length, and the dale is called Colsterdale. The town 

 of Masham stands upon the banks of its stream not far from the 

 point where it joins the Yore, the latter being here 250 feet 

 above the sea-level, and the top of the ridge which separates 

 Colsterdale from Coverdale being upwards of 1500 feet above it. 



From Leyburn to its junction with the Swale the Yore has a 

 course ofnearly thirty miles and through the low country it runs 

 with many windings in a south-eastern direction. Soon after it 

 has passed Masham it becomes the boundary of the North 

 Riding on the south. The gritstone still continues along the 

 banks of the river as far as Tanfield, through the woods opposite 

 the pleasant undulated sylvan grounds of Hackfall. On the 

 north side of the stream we have here Viola sepmcola, Symphytum 

 tuberosum, Car ex strigosa, Bryum uliginosum and Hypnum 

 pratense. A tract of Magnesian Limestone bounds the Grits- 

 tone on the east, the beds oT which extend from Thornton 

 Watlass past Well and Nosterfield, and form a narrow terrace, 

 which, although it scarcely attains anywhere an altitude 

 above the sea-level of 100 yards, yet has a slope in the 

 direction of the dip of its beds towards the Central Valley. 

 The limestone rocks form rapids in the bed of the stream 

 below Tanfield bridge, and margin its northern bank with 

 low cliffs for a short distance. This little tract of Magnesian 

 Limestone, here as southwards, produces several interesting 



