538 REPORT —1904. 
found by Mr. Gibson to coincide with, and perhaps to have been determined by, 
faults known to be mainly of pre-Triassic age. One of these, with a downthrow of 
400 yards to the south, runs from Trentham through Longton, and south of 
Cheadle, while another ranges from near Nottingham to the north of Derby. 
We come now to the south-west of England, where we find striking proofs of 
a still more energetic movement than any yet mentioned having intervened 
between the Carboniferous and Triassic periods. The central part of the Armorican 
axis, as it has been called, after the ancient name of Brittany, trends nearly east 
and west, and keeps to the south of our South Coast ; but we have opportunities 
in Deyon and Cornwall of seeing some of the stupendous effects produced along its 
northern side. A belt of country measuring some 130 miles in width has been 
completely buckled up. Slaty cleavage was superimposed upon the intricate 
folds into which the strata were being thrown, while after or towards the close of 
these phenomena granite was extruded at several points along the belt of dis- 
turbance, a little north, however, of the line alonz which the oldest rocks were 
brought up to the surface. In Devon the Culm-measures are fully involved 
in the movement, but on the other hand the Permian strata, while containing 
fragments of the cleaved and metamorphosed rocks, are themselves wholly free 
from such structures. The age of the folding, cleavage, and extrusion of the 
granite is thus definitely fixed as having been subsequent to the deposition of the 
Culm-measures, but previous to that of the Permian rocks, 
But we may fix the age still more closely. A broad syncline of Carboniferous 
rocks traverses Mid-Devon, and is succeeded northwards by an anticline and by 
an extrusion of granite at Lundy Island, the age of which, however, has not yet 
been definitely ascertained. Still further north in a series of folds and overthrusts 
which traverse the southern margin of South Wales we can recognise the last 
effects of the great Devonshire movement at a distance of not less than 130 miles 
from the central axis, the ground-swell, so to speak, subsiding as it receded from 
the distant storm-area. Here the higher Carboniferous rocks are involved, and 
thus prove that this part at least of the Armorican disturbance was of post- 
Carboniferous age. 
In Dorset, Somerset, and Gloucestershire the Paleeozoic rocks pass eastwards 
under Secondary formations, and are seen no more in the South of England. That 
the disturbance continues, however, is inferred from the fact that it has been 
traced across a large part of the continent of Europe in the one direction and 
across the South of Ireland in the other. The determination of its position there- 
fore, and especially of the effects of its intersection with the Midland disturbances, 
is of the greatest importance in view of the possible occurrence of concealed coal- 
fields under the Secondary rocks. One such intersection is open to observation. 
The Malvern and Devonshire disturbances intersect in Somerset. On investi- 
gating their behaviour as they approach we may notice in the first place that the 
subsidiary axes which form the northernmost part of the Devonshire disturbance 
in South Wales die away one after the other towards the east. Thus an east and 
west disturbance at Llanelly runs a few miles and disappears. ‘The more 
important Pontypridd anticline, which traverses the centre of the coalfield, fades 
away near Caerphilly, while the coalfield itself terminates a little further east, 
its place on the same line of Jatitude being taken by the Usk anticline, which 
trends southwards and south-westwards. So far it might be inferred that the 
east and west folds die away on approaching the north and south Malvernian axis. 
But the Cardiff anticline, which lies south of and was more energetic than those 
mentioned, crosses the Bristol Channel and, emerging on the other side in a com- 
plicated region near Clevedon and Portishead, passes to the north of Bristol and 
holds its course right across the coalfield at Mangotsfield. The coalfield, 
howeyer, lies in what is part of the Malvernian disturbance, for it occupies 
a syncline running north and south along the west side of the main axis of 
upheaval. Though the interruption is local and the strata recover their north and 
south strike to the south of it, yet the east and west axis obviously holds its course 
right through the Malvernian structure. 
Still further south in the direction in which the east and west movements 
