702 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [June 22, 
is hard and massive in part, with calcareous veins and hematite, 
and is also amygdaloidal except where it has been exposed to the 
atmosphere; it is then vesicular and in places much decomposed. 
An upper bed immediately beneath the limestone is very green 
and soft, is veined with calcite, and has also here and there a little 
iron pyrites ; the limestone above is very hard, and also has specks 
of pyrites in it. Going on now up Tideswell Dale by the private 
road, we soon reach the toadstone mentioned at the commencement 
of this paper; and tuis toadstone, I am inclined to think, is of the 
same age as that opposite Litton Mill, although, as will be shown, 
it differs from it in some respects. 
I will now proceed to describe the rocks as seen in the quarry (fig. 1). 
Beneath a thin layer of surface-soil on the slope of the hill is a bed 
of toadstone (a*); the upper portion of this bed is much broken up 
and decomposed, and contains curious concretionary balls of all sizes, 
from that of a walnut up to that of a large cannon-ball; large 
rounded lumps are also stated to occur in the teadstone opposite 
Litton Mill. Underneath this upper portion of the rock the toadstone 
is shattered into large blocks of indefinite shape, yellow outside 
from the effects of weathering, but within of a very dark green (a’) ; 
this rock is extremely hard and dense, and will readily scratch glass. 
I have not analyzed it, but should consider it, judging from its 
appearance, to be a dolerite. In the quarry it attains a thickness 
of 9 or 10 feet; this passes downwards into a coarse and much de- 
composed bed (a*), which is partly amygdaloidal, partly vesicular, 
and about 2 feet thick: some of its cavities contain wad (earthy bin- 
oxide of manganese) in a state of fine powder ; others are filled with 
a mineral which has somewhat the appearance and feel of steatite. 
Some of the prisms of the rock next to be described are coated 
with a mineral which has a similar greasy feel ; to this rock I wish 
to call particular attention. Immediately beneath the toadstone 
rocks, and without any very apparent sharp line of definition, save 
perhaps at one part of the quarry (where the boundary line appears 
rather sharper), lies a thick bed of apparently indurated red clay, at 
least three yards thick (>). This bed presents a very remarkable 
appearance, being perfectly columnar or prismatic, the prisms vary- 
ing in thickness from 5 or 6 inches to about 1 inch, whilst they 
are about 8 or 9 feet long; their lower ends, however, are not well 
seen, being buried in débris, the prisms readily breaking up and 
crumbling. At the north side of the quarry (fig. 1) this columnar 
clay presents a very strange appearance, reminding one, but for the 
colour of the basaltic rock, of the Giant’s Causeway: the columns 
here attain their maximum thickness, and are well exposed for 
many yards, contrasting somewhat sharply with the rock above. 
Their position is nearly vertical, although at the bottom slightly 
bent. On the western side they are again seen, but are of much 
smaller diameter, and are inclined at an angle of 64°, whilst a little 
further on they lie almost horizontally, and present an appearance 
which was not inaptly described by one of the quarrymen as re- 
sembling a mass of corks. 
