12 
of Sciences for 1838 : — " Along the Westerly edge of the 
" coal measures, there are well-known irregularities, occa- 
" sioned by elevations and depressions, across the general 
" range of the series, causing sinuosities in the marginal 
" edges of the coal fields. The lands Eastward, over the 
" ridge contract, and those Westward, in the hollows, expand 
" the width of the coal measures ; so that the first rise, in 
" the North side of the Dun, causes a vacant space between 
" SheiReld and Chapel Town ; and the second rise. South of 
" Sheffield, and in Derbyshire, causes a vacant space in the 
" productive coal measures between the high part of Shef- 
" field Park and Coal Aston ; and in the hollow between 
" these two ridges, the coal is thrown forward under Shef- 
" field. But there is a greater Westward receding (projec- 
" tion) in the Dronfield trough, one side of w^hich, rising to 
" the North, causes a long East and West range through 
" Coal Aston." 
Mr. Hartop said, Mr. Thorp had observed that he stated 
on a former occasion that the strata North of the Dun were 
elevated. What he contended was, that either those on the 
North had been elevated, or those on the South had been 
depressed ; but he never gave a positive opinion, further than 
as to the fact that there was a difference in the level of the 
strata on the two sides of the valley, of nearly 700 yards. 
Geologists found much difficulty from the want of a suf- 
ficiently correct map, shewing the bearing of the minerals ; 
and probably considerable discrepancies would be found be- 
tween the map he produced and that of Mr. Thorp. He 
should confine himself to the facts he had ascertained from 
his own observations ; and he thought, if the information of 
the different members could be collected on a map on a 
large scale, it would greatly increase the usefulness of the 
Society. He then proceeded to make some remarks on the 
Thick coal, which was worked at Beighton, at Handsworth, 
at Attercliffe Common, at Masbro', and at Earl Fitzwilliam's 
