2 47 
the great Derbyshire Denudation . 
field of Derbyshire, Nottinghamshire, and Yorkshire, under- 
laying the yellow-lime rock, as lower in the series than any 
others of the coal-measures alluded to above, and that the 
fourth limestone rock, which extends from Castleton in Der- 
byshire, southward to Weaver Hill, near Wooton and Ramsor 
in Staffordshire, is the very lowest which is known in Britain, 
and which may account for the circumstance, that the mineral 
veins and the strata in which they occur in Derbyshire, pre- 
sent some phenomena, which are said to occur no where 
else. 
I shall proceed now to describe the circumstances, under 
which this great elevation and denudation of part of the Der- 
byshire strata seems to have happened, which is, by a series 
of three or four separately lifted tracts, one within the other, 
as represented in the small sketch map annexed. The outer 
or least lifted of these tracts is bounded on the south by a 
fault, that I have distinguished by a full line, where ascer- 
tained, and by slight dots where only inferred, and denomi- 
nated it the great Derbyshire fault, which is perfectly defined 
from near Nottingham across Derbyshire, to the north side 
of Stone in Staffordshire (except in a few places where gravel 
covers it), by having red marie, lying nearly horizontal, on 
all its south side, and different strata on its north side, as will 
be mentioned further on : the eastern fault or side of this first 
raised tract is not visible within the limits of my Survey, like 
the southern, on account of the vast accumulation of quartz 
gravel in Sherwood Forest, and the peaty alluvia north of it : 
but it seems probable to me, that its range is from about the 
town of Nottingham, east of Mansfield, east of Worksop near 
, Bawtry, west of Thorne in Yorkshire, and flow much further 
