Cardiff and Barry (a town created on a sandy
island by the excavation of a great dock to form an outlet for the
mines). In the north of the field, where the limestone crops out and
supplies the necessary flux, Merthyr Tydfil has become great through
iron-smelting; and in the west Swansea is the chief centre in the
world for copper and tin smelting. The unity and ruggedness of the
highlands of Wales have proved sufficient to isolate the people from
those of the rest of South Britain, and to preserve a purely Celtic
race, still very largely of Celtic speech.

_Cornwall and Devon._--The peninsula of Cornwall and Devon may be
looked upon as formed from a synclinal trough of Devonian rocks, which
appear as plateaus on the north and south, while the centre is
occupied by Lower Carboniferous strata at a lower level. The northern
coast, bordering the Bristol Channel, is steep, with picturesque
cliffs and deep bays or short valleys running into the high land, each
occupied by a little seaside town or village. The plateau culminates
in the barren heathy upland of Exmoor, which slopes gently southward
from a general elevation of 1600 ft., and is almost without
inhabitants. The Carboniferous rocks of the centre form a soil which
produces rich pasture under the heavy rainfall and remarkably mild and
equable temperature, forming a great cattle-raising district. The
Devonian strata on the south do not form such lofty elevations as
those on the north, and are in consequence, like the plain of
Hereford, very fertile and peculiarly adapted for fruit-growing and
cider-making. The remarkable features of the scenery of South Devon
and Cornwall are due to a narrow band of Archaean rock which appears
in the south of the peninsulas terminating in Lizard Head and Start
Point, and to huge masses of granite and other eruptive rocks which
form a series of great bosses and dykes. The largest granite boss
gives relief to the wild upland of Dartmoor, culminating in High
Willhays and Yes Tor. The clay resulting from the weathering of the
Dartmoor granite has formed marshes and peat bogs, and the desolation
of the district has been emphasized by the establishment in its midst
of a great convict prison, and in its northern portion of a range for
artillery practice. The Tamar flows from north to south on the
Devonian plain, which lies between Dartmoor on the east and the
similar gran