SKETCH OE THE GEOLOGY OF DERBYSHIRE. 15 
OLD END SHAFT. 
BPIMERLONEG meat ay) «2. 5,2 const sa decac aeeee 32 fathoms 
FP OAUSLOUC Hts tes. -o 0200 cncce ccs eee 8 do. 
MTMIENLONGuesstcncnsc-oc8e cnc seecacces conees ore 26 do. 
PPoddStONE est sette re. UN URES 61 do. 
I was informed that one of the clays in the upper limestone of the 
“Glory” shaft thickened out towards the E. and became toadstone 
at the “ Old End ;” a circumstance which is believed also to take place 
in other parts of the limestone district, but which requires farther con- 
firmation before it can be received as an ascertained fact. Many cir- 
cumstances, however, unite to make some such irregularity probable, 
with regard to the upper toadstone at least.* The circumstance of 
portions of the mountain limestone being brought up to the surface 
wherever forces of disturbance have acted in a sufficiently powerful 
manner to break through the superincumbent rocks, is important, as 
showing us the continuity of the limestone formation ; that it is not a 
mere patch existing only in that part of the district where it forms 
the surface of the ground, but that it extends under the adjacent 
country for some miles at least, without losing one of its usual cha- 
racters, or at all diminishing in thickness or other qualities. 
THE COAL MEASURES 
Are the next group of rocks which engage our attention. They 
are, indeed, as before shown, only the upper part of that group of 
which the millstone grit is the lower, the division being one purely of 
convenience. It must necessarily happen, therefore, that the position 
of the one is in accordance with that of the other. Thus, on the W. 
of the county, where the millstone grit dips to the W. the coal mea- 
sures of which it forms the base dip likewise in that direction. Of 
the narrow coal-field on the Cheshire side, this general position of the 
beds is all I know. On coming to the eastern tract of gritstone, we 
find, in like manner, when it passes beneath the coal-field, that the 
coal measures have likewise an easterly inclination. This easterly 
dip of the coal measures is true of the whole of the Derbyshire and 
*“ The inquirer must be cautious in receiving the accounts ot the common 
miners, as they not unfrequently call all clay lying between beds of lime- 
stone toadstone, because that rock is itself generally accompanied by clay. 
