554 
Mr. Winch on the Eastern Part of Yorkshire . 
grains or globules of which the mass is composed, vary from the 
size of mustard seed to those of large peas. 
In the vale of Pickering, and even as far west of Thirkleby, a 
hard shell-limestone is quarried. Its situation appears to be sub- 
ordinate to the oolite and sandstone ; for at Thirkleby it bassets 
out at no great distance from the alum-shale formation. It is of a 
pale bluish colour, close grained texture ; fracture slaty when bro- 
ken, with large fragments ; lustre glimmering (probably from 
numerous minute fragments of shells) ; and containing small bivalves. 
When weathered it becomes externally rusty brown. It is sono- 
rous, and breaks into tabular fragments. 
The Yorkshire wolds are undulating hills occupying a conside- 
rable part of the south and south-west, the district of Yorkshire 
to which our observations are confined. These commence on the 
Derwent, and stretching southwards, dip under the alluvial soil 
which covers the flat country in the vicinity of the Humber. 
Hard chalk is the prevailing rock through the whole of this 
part of the district, and the high cliffs at Flamborough head serve 
to convey a just notion of its thickness. With the exception of 
iron pyrites this chalk does not appear to be metalliferous, but 
nodules of grey flints frequently occur in it. 
Here it may not be amiss to mention that the same species of 
rock skirts the sea shore below Lowth in Lincolnshire, and there 
rests upon numerous beds of ash-grey bituminous shale, which crop 
out towards the west. When burnt, this shale emits a fetid odour, 
which I thought might arise from animal matter, as it is filled with 
the fragments of small bivalve shells, but on analysis no ammonia 
was detected. 
Among the rejectamenta of the sea on this coast, fragments of a 
peculiar kind of coal abound, resembling the brown or Bovey coal 
