Si DESCRIPTION OF THE ROCKS 
thus occupy nearly the centre of what may be called an immense 
denudation of the upper part of the Yoredale series. The main lime 
stone, commencing in the Greta above God’s bridge, (west of Bowes, 
extends to the south by a sinuous course along the edge of the 
moors above Hope, Scar gill, and Barningham, and afterwards by 
Dalton, Sayles, Ravensworth, Wharleton, and Gffling; it then turns 
obscurely round a slightly elevated country to Moulton and Middleton 
Tyas, where it resumes its importance and suddenly ends. From Gillino- 
the northern edge of this denudation passes by Hartforth and Browston 
Rokeby > HUtt ° n ^ ° f F ° rCett ’ and returns to the Tees near 
Tee M.-Fr°m Eggleston near Rokeby to a little above Eggl es . 
ton near Middleton, the Tees runs entirely in plates and grits which 
lie over the mam limestone. It may be considered as crossing a 
depression of strata, occupying a broad area between and parallel to 
the Lune and the Greta, (east by north). This depressl t con- 
tinued into Durham between the Wear and the Tees, as indicated 
by the westward extension of the lower coal series in Cockfield fell 
&c. Fr °n, Miclileto" the limestone country expands over the whole 
of the north-west angle of Yorkshire, between the Lu„e the T 
and Maisebeck ; but in this part of the country an unexpected a“d 
very important rock is interposed amongst the limestones in such 
masses as to predominate in the general aspect of a large region and 
give to upper Teesdale the character of a basaltic formation. ’ 
Nearly in the centre of the triangular space between the Tees 
and the Lune rises the mountain of Mickle fell, probably the loftiest 
in Yorkshire, but inferior to Cross fell. This mountain is g irt bv 
scars of main limestone, bearing toward the western ends two patches 
of superincumbent grits and shales. The limestone surface is about 
one thousand five hundred feet above the basaltic rocks at the Hi^h 
force, and about one thousand feet above those at Caldron snout The 
following is a section of beds seen between the foot of Caldron force 
and the limestone summits of Mickle fell. 
