72 SECTIONAL ADDRESSES 
compared by Professor Kendall }° to the crack lattice produced by twisting 
slabs of glass, and the differential lifting of the Pennines was suggested 
as the agency of the twist. The analogy is a good one in that it reminds 
us that the simplest kind of stress may in a single operation by resolution 
produce the diamond fault-block pattern. North of the Don the most 
persistent faults are longitudinal in the flanks of the wide West Yorkshire 
trough, wherein they converge and anastomose, with rise of pitch north- 
westward. In this area transverse faults preserve an almost constant 
north-easterly direction. Most of their movement was pre-Permian, but 
some have since increased their displacement, and certain east-west faults 
which are longitudinal in the flank of the northern boundary anticline 
extend into the Trias. There is to the north of the Don anticline, near 
Rotherham, one area twenty square miles in extent without a charted 
fault. That, however, is exceptional, and triangular or quadrangular 
blocks, of a few score acres to three or four square miles, are characteristic 
of the Yorkshire Coalfield. 
In Derbyshire, and with less certainty in Nottinghamshire, the fault 
pattern is recognisable as an extension of that better defined in Yorkshire, 
but local folds of variable pitch dominate the Derbyshire structure. 
Faults following the general north-west elongation of the coalfield basin 
join with the arcuate groups, and bend eastward to cut across the limestone 
area of the High Peak. In Derbyshire there is no strong development of 
north-east fractures, and the few faults which break the Permian outcrop 
south of Sheffield are either north-westers, or in the south, near Notting- 
ham, where they become important, members of the east-west arcuate 
system of the southern ending of the Pennines. 
In Lancashire transverse faults have cut the coalfield into boat-shaped 
strips which taper sharply where neighbouring members of the same fault 
series join. About Manchester the master fractures traverse steep 
measures in the trough of the wide syncline as it pitches to the Cheshire 
Basin, and are effective in reducing the average rate of dip. The 45° 
hade of these fractures is exceptional, and must have come by tilting as 
displacement continued during and after the deposition of the Permian 
and Trias. South of Manchester the fractures bend southwards as they 
tail off in the sharp rise of measures in the Cheshire margins of the Peak. 
Towards the north the leading fault lines take a double bend, and swing 
round first westwards and then northwards to cross the Rossendale 
anticline. In North Lancashire, and all the way from Wigan to Todmorden, 
the pattern is broken by the great encircling fault group into which both 
from north and south the local strip fractures trail. In South Lancashire 
to the west of the great Pendleton-Irwell Valley Fault, the north-west 
breaks are less powerful and more widely spaced. There are also strike 
faults, possibly an arcuate series, in the edges of the Cheshire Basin, and 
about Wigan and St. Helens a diamond block pattern, not unlike that of 
Yorkshire, has resulted. 
The swarm of faults which in North Wales slices the country into 
narrow strips range generally north and south, with some eastward 
convexity, and cut across the horseshoe folds obliquely. Northwards 
15 P. F. Kendall and H. E. Wroot, Geology of Yorkshire, p. 243 (1924). 
