WILLIAM SMITH : HIS MAPS AND MEMOIRS 
87 
grooves down from top to bottom of the pit, for opposite ends of 
the cross bars to move in with an enlarged place mid-way for their 
passing, my learned friend could not understand the mechanism, 
though I was occupied nearly the whole of a long stage in explaining 
it to him. 
" The rocks of the Yorkshire coalfield, everywhere so well 
developed, opened to my mind new views of the facility of obtain- 
ing on the surface clear notions of the coal-measure stratification ; 
and at Banktop, near Barnsley, I found some of the rocks of this 
series strongly developed. 
" Leeds being near the extent of the coalfield, we found that 
further north there w^ere no canals, but determined on seeing York 
Minster ; and thus, in crossing Tadcaster Moor, I had a clear view 
of the magnesian limestone, which is a rock unknown in the south. 
" From the top of York Minster I could see that the Wolds 
contained chalk by their contour.* 
" We here had time enough to indulge ourselves with a good 
dinner and a pine-apple at the Black Swan, and resolved upon a run 
up to Newcastle to see the celebrated collieries there ; and, after the 
first stage from York, I recognised in the Hambleton Hills the 
features of the Cotswold Hills viewed from the vale of Gloucester ; 
saw near Thirsk the red marl in the road, and found that along 
Leaming-lane we were travelhng upon red sandstone. The yellow 
limestone appeared again at Pierce Bridge, and at Ferry Hill they 
were working coal under it. 
" Here it presented a well defined escarpment boundary to the 
Durham coalfield, as it did to that of Yorkshire ; but these northern 
coal-measures were observed to be much more obscured by a thick 
cover of loose and mixed matter." 
At Heaton Colliery, near Newcastle : — 
*' The mode of dividing their shafts and mother-gates by 
* Of this Phillips says : — " This was in fact the only authority he 
could rely upon for drawing, in 1800, the continuations of the Chalk 
of Wiltshire and the Oolite of Somersetshire through the eastern parts 
of Yorkshire, but he drew them with a considerable approximation 
to accuracy." 
See under Martin Lister, 1683, below, where the Chalk Wolds are 
distinctly referred to. Of course Smith may not have kno-wTi of Lister's 
paper. — T.S. 
