411 
THE GLACL\TIOX OF THE DOX AXD DEARNE VALLEYS. 
BY W. LOWER CARTER, M.A., F.G.S. 
In studying the physical geology of the Don River-System,* 
my attention was specially directed to the evidences of glacial 
action in that area, with the object of ascertaining whether 
glaciation had anything to do witli the interesting diversions 
of the Don, Dearne, Dove, and Rother. Certain valleys also 
attracted my attention as exhibiting abnormal features with 
respect to the present drainage of the district, and there appeared 
to be two or three cases of glacial diversion of streams, which 
necessitated an inquiry as to what their relations might be to 
the altered conditions which a period of glaciation would have 
produced. 
The present paper is an attempt to piece together these 
scattered fragments of evidence into a continuous glacial story, 
and the result indicates a phase of glaciation subsequent to the 
chief work of the erosion of the Calder Valley by the overflows 
of the Burnley and Summit (Todmorden) gorges, and prior 
to the formation of the York and Escrick moraines. The work 
of denudation over the valley of the inner Don and Dearne 
appears to have been so severe that the evidence has in a large 
degree been removed, whilst the central Triassic plain is such 
a complex of deposits that it may need years of careful work 
before its conflicting evidence can be reconciled. This paper 
does not attempt to deal with the glacial evidence beyond Balby. 
The area dealt with has been so fuUy described in the author's 
paper on the Evolution of the Don River-System* that there 
is no need to refer to it here any further. 
The glacial evidence has been gathered from the etiological 
Survey Memoir on the Yorkshire Coal-field, and from the careful 
descriptions added to each patch of gravel marked on the six-inch 
geological maps. The valuable reports of the Yorkshire Boulder 
Committee have furnished important facts, whilst the author 
has taken opportunities of going over portions of the ground 
* See p. 388. 
