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which operates most powerfully on parts least exposed to the
weather.
Most of the rocks of this division effervesce in some degree with
acids, but more especially those possessing the slaty structure.
They are not very productive of metallic ores, although they
afford a considerable variety. A vein of lead ore has for some
years been profitably worked at Greenside, in Patterdale; copper
has formerly been got at Dalehead, in Newlands, which is near the
northern boundary of the division - it consists of grey and
purple copper, with specimens of malachite. A mine at Coniston,
near the southern boundary, has been for several years
extensively worked; it produces the yellow sulphuret; and a vein
of the same was a few years ago opened at Wythburn. Small veins
of iron ore are frequently met with, but scarcely thought worth
notice. The famous plumbago, or black-lead mine of Borrowdale, is
also situated in this division: but no organic remains have been
discovered in it; and if Mr. John Ruthven, the indefatigable
fossil hunter, and intelligent curator of the Kendal Natural
History museum, has found any in the preceding, it has been of
very rare occurrence.
The THIRD division, or Silurian group - forming only inferior
elevations - commences with a bed of dark-blue transition
limestone, containing here and there a few shells and madrepores,
and alternating with a slaty rock of the same colour; the
different layers of each being in some places several feet, in
others only a few inches in thickness. This limestone crosses the
river Duddon near Broughton; passing Broughton Mills, it runs in
a north-east direction through Torver, by the foot of the Old Man
mountain, and appears near Low Yewdale and
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