4 SKETCH OF THE GEOLUGY OF DERBYSHIRE. 
as that on the W. N. and E. as, for some miles west from Wirks- 
worth, the limestone is cut off by a great fault, which causes a sudden 
downeast (instead of a regular dip) to the S. All the way to the 
Dove the limestone is much broken and disturbed, but whenever a 
dip is seen along the whole line between Wirksworth and Thorpe, it 
is, I believe, invariably towards the south. Having established the 
fact of the limestone dipping, at each part of its boundary, from 
the central portion of the district, and passing, for the most part, re- 
gularly under the superior strata, the next fact that would strike our 
attention is, that we cannot proceed far from the boundary towards 
the central position without coming abruptly to the edge of a precipice 
or steep slope, or, geologically speaking, an escarpment. This is a 
necessary consequence of the position of the rocks, since, as the beds 
vise towards the central portion wherever they are cut through by a 
fault, and the inside piece depressed, or a valley in any way formed, 
the broken edges of the beds must be exposed to view, and a steep 
cliff or escarpment formed. From the inclination of the beds, too, the 
escarpments on the western side must face the E. while those on the 
eastern side look towards the W.* This position of the escarpments 
and inclination of the strata, however, must be understood very gene- 
rally, and does not hold good on advancing far into the limestone 
country, there being nothing like any well-defined central ridge or 
axis of the district from which the beds dip equally on either hand, 
all the central portion being broken through by faults, and everything 
like regularity of position destroyed. On looking ata map on which 
the outline pointed out before has been traced, it will be seen that the 
limestone district is narrowest in the middle, or between the Dove 
and the Bradford, while N. and S. of that tract it expands to a consi- 
derable extent. This middle tract is comparatively undisturbed, and 
I am not at present aware of any place between Hartington and Mid- 
dleton, by Youlgreave, where the toadstone exists at the surface. In 
all the limestone district, however, north of this line, we continually 
find the toadstone either at the tops of the hills or the sides of the 
* Tt would have been next to impossible, for instance, for a steep cliff to 
have been formed, like the Matlock High Torr, on the opposite side of the 
river, or with its face to the E. because, as soon as the ravine was formed, 
the beds which dip towards it on that side, being cut through, would be de- 
prived of their support, and slide one over another into the valley: this, in 
fact, has, at some time, taken place, and the side of the hill opposite the 
High Torr is covered with broken ruins. The beds of the Torr itself, on 
the contrary, dipping from the ravine and into the hill, are supported, and 
can scarcely by any possibility fall into the river, unless deeply undermined. 
