CARTER : GLACIATION OF DON AND DEARNE VALLEYS. 425 
tinuous. Thus the Stainmoor glacier would increase as the 
Pennine ice decreased. 
This invasion of the Don-Dearne area would necessarily 
deflect the Calder southwards, and impound the considerable 
drainage of the eastern slopes of Wliarncliffe Chase and the ridge 
northwards to Hoyland Swaine, and a lake or lakes would be 
formed. The next section is an attempt to outline these lakes, 
and to indicate their lines of overflow at successive periods. 
III. — Glacier Lakes. 
Are there any evidences of the existence of such glacier 
lakes in the Don-Deame area, and, if so, can we identify their 
boundaries and locate the channels by which they were drained ? 
This is a difficult problem, as the whole area lies comparatively 
low, and appears to have undergone an enormous amount of 
denudation, as is indicated by the widely-scattered erratics 
and the comparative absence of boulder-clays. That there must 
have been such a closing of the Don gorge as would produce a 
great lake is indicated by the glacial drift at Ashfield and Cadeby 
at the 225-foot contour on opposite sides of the gorge near Conis- 
brough, showing that ice must have filled the gorge at least up 
to that level. Hampole gorge being then covered by ice, 
a great lake would be formed, having its ramifications far up the 
valleys of the Don, Dearne, Sheaf, and Rother. We can hardly 
in the nature of things expect much evidence of lake deposits 
in this area, but, in addition to the warp in the Staincross section, 
the Geological Surveyors report 4-9 feet of brick-earth and clay on 
gravel at Parkgate in the Don valley, and of 3-7 feet of brick-earth 
at 90 feet O.D. at Wombwell, in the old Dove valley ; also a 
considerable thickness of silt coveiing vegetable matter and sand 
was found at the Old Mill section, Barnsley, in the Dearne valley. 
In addition to these warps there are widely- spread deposits 
of yellow clay, which may be partly decomposed shale and 
limestone, partly residual boulder-clay, and partly also lake 
warp. 
In commencing the study of this area my attention was 
at once attracted by certain valleys which appeared to be out 
of the line of drainage, and which traversed significant lines of 
