l8 BAKER*S NORTH YORKSHIRE. 



neighbourhood of Middleton causes a difference of some 

 hundreds of feet between the elevation of the beds on the 

 opposite sides of the dale. So that the triangular tract of 

 country enclosed between the Tees, the Lune, and Maize Beck 

 consists of a pyramid of beds of the Yoredale Rocks elevated 

 upon a floor of Basalt and Mountain Limestone lifted con- 

 siderably higher than the corresponding strata in the country 

 which immediately surrounds it. The Main Limestone forms 

 the general plateau of the culminating Mickle Fell ridge, and 

 there is a cap of sixty feet of gritstone over it at the western or 

 highest end of the ridge, which is the highest point in York- 

 shire, and which reaches an elevation of nearly 2,600 feet. The 

 height reached by the Yoredale Rocks in the Teesdale district 

 is its maximum elevation in Britain. Here the Main Limestone 

 is 70 feet thick and the Underset Limestone 24 feet thick, with 

 a space of about 80 feet between them. Complicated disloca- 

 tions, especially the three faults to which reference has just been 

 made, and a fourth which is called the Burtree Ford dike, and 

 which ranges from Langdon Beck across the east end of Falcon 

 Glints and Cronkley Scars towards the head of Lunedale, caus- 

 ing a down-throw on the east to the extent of about 200 feet, 

 produce great confusion in the stratification of the lower beds 

 of the series. These vary considerably in thickness in different 

 places, the greatest thickness anywhere attained by a lower 

 limestone being 40 feet and the space between the Underset 

 Limestone and the Tyne Bottom Limestone ranging from about 

 300 to 600 feet. Between the Main Limestone of Mickle Fell 

 and the Tyne Bottom Limestone of the White Force, there is a 

 difference in level of 850 feet, but here the Burtree Ford dike 

 intervenes. In Alston Moor the Yoredale Rocks are 495 feet 

 thick, 350 feet of which is made up by non-calcareous beds, 

 the principal of which are two bands of hard grit-stone called 

 respectively the Brigstone Hazle and the Nattriss Gill Hazle. 



(7) The Millstone Grit Series. — For a typical section of 

 this series as we have it in North Yorkshire we must go either 



