GEOLOGY OF PART OF SOUTH DURHAM. 191 



the Tees, opposite to Winston, Gainford, and Pierce Bridge. 

 In proceeding south from any of these villages, lower and lower 

 beds of the Carboniferous formation are found rising to the sur- 

 face, until at Forcett, Melsonby, Barton, and as far east as Mid- 

 dleton Tyas and Moulton, thick masses of Mountain Limestone 

 form the surface rock of the country. This latter rock, which 

 we take to be the " Great Limestone " of Weardale, contains the 

 characteristic marine fossils, (shells, corals, and crinoids,) of the 

 Carboniferous system ; and at Merrybent, near Melsonby, it is 

 being actively mined for lead and copper. The ground it occu- 

 pies is where the Magnesian Limestone might naturally have 

 been looked for ; but the range of the latter formation in North 

 Yorkshire is broken up into a few isolated patches for a distance 

 of nearly twenty miles, and from a little south of the Tees to 

 Catterick Bridge it would appear to be entirely absent. 



The presence of Carboniferous limestone so far to the east, 

 touching in fact on the New Red Sandstone area of Yorkshire, 

 is a point of considerable significance. Viewed in connection 

 with the prevalence of a northerly dip between its outcrop and 

 the great dislocations lately noticed, we are inclined to look 

 upon it as indicating the former existence of a great fold or an- 

 ticline in the Carboniferous strata of this region ; the limestone 

 of Middleton Tyas, Moulton being but the partially denuded and 

 exposed western portion of it, and the outcropping strata of the 

 Yoredale rocks, Millstone Grit, and Coal Measures previously de- 

 scribed, but a portion of its northern flank. 



We are not in a position to speak as to how far this idea is 

 borne out by the relations of the Carboniferous strata further to 

 the south ; but the observations of Professor Sedgwick in the 

 memoir before quoted support it. To the north of Pontefract, 

 he describes the strike of the Coal Measures to be to the north- 

 east, and their dip to the south-east at a considerable angle. 

 Further north, near Church Garforth, and within a mile or 

 two of the northern limits of coal-field, he says that the dip 

 of the Measure is nearly due south.* In Professor John Phil- 

 lips's Map of the Geology of Yorkshire, the outcrop of the coal 



* Trans. Geol. Soc, 2 Ser., Vol. III., pp. 58, 59. 



