W. Gimn — Carhoniferous Rocks of England ^ Scotland. 343 



basement conglomerate which rests unconformably on the highly 

 inclined Silurian rocks. The lower part of the section is composed 

 of a solid mass of limestone, 600 to 700 feet in thickness, while 

 the upper part consists mainly of an alternating series of sandstones, 

 shales, and limestones, to which Phillips gave the name of Yoredale 

 Eocks, because he considered they were typically developed in 

 Yoredale (Wensleydale). In this and the other sections the 

 limestones are particularly marked, because it is by means of 

 them principally that the rocks in different places are correlated. 

 The Yoredale Series, then, in the Ingleborough section ranges 

 from the Hardraw Limestone up to the highest limestone — the Main 

 or Twelve- Fathom — but two of the limestones generally occurring 

 elsewhere are wanting in this section, so that it is certainly not 

 a typical one of the Yoredales. Above the Main Limestone here 

 there occurs a thickness of 100 to 120 feet of shale, and the hill 

 is capped by coarse Millstone Grit. 



Tiae Wensleydale section is mainly that proved in Keld Heads 

 Mine between Leyburn and Redmire. It will be noticed at once 

 that the Yoredale Limestones are here both thicker and more 

 numerous than at Ingleborough. Four of the limestones are each 

 about 60 feet in thickness, whei'eas only the Main Limestone on 

 Ingleborough attained this thickness. The two additional limestones 

 are the Underset and the thin limestone next below. It should be 

 stated that the Underset is here abnormally thin, it being usually 

 about twice the thickness given. The ' Fossil ' Lime, on the other 

 hand, is usually only about one-half of the thickness here given, so 

 it must be understood that the section does not stand for the whole 

 of Wensleydale. The Main Limestone is often, perhaps generally, 

 considerably more than 60 feet thick ; in fact, it obtained the name of 

 ' Twelve-Fathom ' because it approximates to 72 feet in thickness. 

 The upper part only of the Mountain Limestone is to be seen in 

 Wensleydale, and its total thickness here is unknown, but it has 

 already, as far as its upper members are concerned, begun to admit 

 intercalations of sandstone and shale, and thus to approximate in 

 character to the Yoredale Series above. In the dales to the north of 

 Wensleydale somewhat similar sections may be obtained, and there- 

 fore it is unnecessary to give a detailed account of each. In the first 

 valley, that of Swaledale, the section is very like that of Wensleydale, 

 except that some of the limestones are thinner. In Teesdale we find 

 that the Middle Limestone has separated into three limestones 

 known as Scar, Cockleshell, and Singlepost Limestones, while nearly 

 all the Yoredale Limestones, except the Main, are considerably 

 thinner than in the dales farther south. Several comparatively thin 

 limestones represent the upper part of the Great Scar Limestone of 

 Ingleborough, while the lower part is a solid mass of about 200 feet 

 in thickness, known locally as the Melmerby Scar Limestone. 

 Below this is a variable but not thick mass of basement conglomerate, 

 resting on the Silurian rocks which are exposed in the valley 

 between the High Force and Caldron Snout. Not many miles to the 

 west, in the Pennine escarpment, a thick series of sandstones occurs 



