48 



Corbett : Glacial Geolooy of Doncaster. 



Carboniferous Limestones, including Yoredales and 

 Cherts. — These are abundant and very varied. Many are 

 highly fossiliferous. A yellow fine-grained limestone has spines 

 of Hvalonoiia parallella, and some of the Cherts consist almost 

 entirely of the same fossil. 



Igneous Rocks. — These, compared with the others, are very 

 few. One may examine thousands of boulders without finding 

 anv far-carried erratics among them. Nevertheless a consider- 



EXPLANATION OF MaP. 

 Black = Boulder Clay. Vertical lines = Magnesian Limestone. Dots = 

 Gravel composed chiefly of Carboniferous Rocks. Horizontal Lines = 

 Gravels composed chiefly of Quartzites. Crosses = Gravels containing- 

 a mixture of Carboniferous and Quartzite Rocks. Unmarked portion = 

 Warp and Peat. 



able number have from time to time been found, and ainong 

 them are : — Shap Granite, Ennerdale Granite, Quartz Por- 

 phyry from the Vale of St. John ; Augite Andesite from 

 Borrowdale ; Diabase from Eycott Hill ; Whin Sill and 

 numerous ashes, larvas, and aggloinerates. 



Naturalist, 



