586 
a minor scale, into southern Pembrokeshire." * The same 
prevailing lines were laid down so long ago as 1822 in 
the map which accompanies Buckland and Conybeare's Geo- 
logical description of the south-west coal-field of England, f 
In Yorkshire they are not less conspicuous, and Phillips 
has marked them very distinctly in a sketch-map which 
accompanies the diagrams of his Geology of Yorkshire.^ 
In the Carboniferous district of Yorkshire, the Pennine 
Fault, and the South Craven anticlinals, may be taken as 
representing the "N. and S., and the E. and "W. systems 
respectively. Similarly, in the Rev. J. Cumming's Geology 
of the Isle of Man, a very perfect system of rectangular lines 
is described as affecting the Carboniferous rocks of Castle- 
town. § The general direction of these lines is usually 
constant over considerable areas, though instances of local 
variation are not wanting. The E. and W. direction of the 
South Craven portion of the Pennine Fault is an example 
of such deflexion. On the whole, the phenomena are just 
such as may be looked for, when a contracting force of 
uniform direction acts upon strata whose lines of least resis- 
tance are not parallel. 
It is an interesting and not very difficult task to determine 
approximately the date of the second of these two systems of 
disturbance, that with which we are immediately concerned. 
It is plain that as the grits and shales are thrown off by the 
protruded limestone, the movement did not take place before 
the deposition of the Upper Carboniferous strata. This gives 
us an ancient limit ; the disturbance did not occur before the 
close of the Carboniferous period. We find again that the 
dolomitic conglomerates of Bristol and Kirkby Stephen, and 
the Lower New red sandstone of Knaresborough lie hori- 
* De la Beche. Memoirs of the Geological Survey, vol. i., p. 222. 
+ Geological Transactions, Second Series, vol. i. 
$ PI. 24, No. 14. § Geological Journal, vol. ii. 
