e region may
be looked upon as formed by an arch or anticline of Carboniferous
strata, the axis of which runs north and south; the centre has been
worn away by erosion, so that the Coal Measures have been removed, and
the underlying Millstone Grit and Carboniferous Limestone exposed to
the influences which form scenery. On both sides of the arch, east and
west, the Coal Measures remain intact, forming outcrops which
disappear towards the sea under the more recent strata of Permian or
Triassic age. The northern part of the western side of the anticline
is broken off by a great fault in the valley of the Eden, and the
scarp thus formed is rendered more abrupt by the presence of a sheet
of intrusive basalt. Seen from the valley, this straight line of lofty
heights, culminating in Crossfell, presents the nearest approach in
England to the appearance of a mountain range. In the north the
Pennine region is joined to the Southern Uplands of Scotland by the
Cheviot Hills, a mass of granite and Old Red Sandstone; and the
northern part is largely traversed by dykes of contemporary volcanic
or intrusive rock. The most striking of these dykes is the Great Whin
Sill, which crosses the country from a short distance south of Durham
almost to the source of the Tees, near Crossfell. The elevated land is
divided into three masses by depressions, which furnish ready means of
communication between east and west. The South Tyne and Irthing
valleys cut off the Cheviots on the north from the Crossfell section,
which is also marked off on the south by the valleys of the Aire and
Ribble from the Kinder Scout or Peak section. The numerous streams of
the region carry off the rainfall down long valleys or dales to the
east and the south, and by shorter and steeper valleys to the west.
The dales are separated from each other by high uplands, which for the
most part are heathery moorland or, at best, hill pastures. The
agriculture of the region is confined to the bottoms of the dales, and
is of small importance. Crossfell and the neighbouring hills are
formed from masses of Carboniferous Limestone, which received its
popular name of Mountain Limestone from this fact. Farther south, such
summits as High Seat, Whernside, Bow Fell, Penyghent and many others,
all over 2000 ft. in height, are capped by portions of the grits and
sandstones, which rest upon the limestone. The belt of Mills