47 

 GLACIAL GEOLOGY OF THE NEIGHBOURHOOD OF 

 DONCASTER. 



HERBERT H. CORBETT, M.R.C.S. 

 Doncaster. 



The phenomena presented by the g-lacial g-eolog-y of this locality 

 having- been a puzzle to glacialists for some time, il ma\- be 

 worth while to make a statement 0*1 the observed facts, apart 

 from any theories in connection therewith. 



Firstly, there is at Balby an isolated patch o'i Innilder Clay 

 about one mile long^ and half mile wide, with its long- axis 

 runnings nearly from west to east. Its northern side is bounded 

 by Bunter Sandstone, with a capping- of g-ravel in some parts. 

 The relations of the Boulder Clay and the Bunter were well 

 shown during- some excavations in connection with the building" 

 of the Doncaster Workhouse at Balby a few }ears ag-o. The 

 clay was seen to rest upon the sandstone at ang^les varying- 

 from 40° to 10", the steeper ang-les being at the western end, 

 and the slope being; from north to south. In some sections 

 larg;e ang-ular frag-ments of the sandstone were seen embedded 

 in the clay. The base of the clay has been exposed in many of 

 the sections at the Balby Brickworks, and it is always found 

 to lie on a worn surface of Bunter. Its relation to the outlier 

 of Magnesian Limestone on its southern side has never been 

 exposed. The maximum thickness of the clay is about 40 feet. 

 Eastwards it gradually diminishes in thickness until it merges 

 into the low-lying- land of Potteric Carr. The contained boulders 

 are as follows : — 



Permian Marls and G^■FSL'.M. — Numerous. 



Lower Magnesian Limestone. — Ver}' numerous and many 

 of them very large. Many of these are fossiliferous, containing 

 casts oi Aximiis, Mya, Turbo, etc. The fossil bed whence they 

 are derived crops out near Hampole and at several other places 

 along the escarpment of the Magnesian Limestone, e.g., Conis- 

 borough and Clifton. 



Coal Measure Rocks. — These far outnumber all others. 

 They consist of Grits, Sandstones, Gannister, Shale, Coal, 

 Cannel, Clay-Ironstone, etc. Mr. Hemingway, of Barnsley, 

 who has examined them, refers a large proportion of them to 

 the Lower Coal Measures. 



Millstone Grits. — \'ery numerous. 



1903 Februarj' i. 



