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grained sienite, in which form it extends through the mountains
quite across Ennerdale, as far as Scale Force, and to the side of
Buttermere Lake. It contains veins of red hematite and micaceous
iron ore. Another variety of granite with reddish felspar in
large crystalized masses, is found on Shap Fells, and may be
observed in situ on the road side near Wasdale Bridge,
about four miles south of Shap.
Carrock Fell consists of a rock generally classed with the
sienites, but varying in appearance in different parts of the
mountain. It contains (besides the usual ingredients of quartz
and felspar) hypersthene and magnetic or titaniferous iron ore in
various proportions. Near this, a considerable quantity of lead
ore and some copper has been procured: the lead, being smelted
and refined, yields a good portion of silver.
A reddish porphyritic rock occurs on both sides of St. John's
Vale, from two to three miles east of Keswick; and a vein or dyke
apparently related to the same, but far more beautiful, (being
composed of crystals of quartz and bright red felspar, imbedded
in a brownish red compact felspar,) is found on Armboth Fell, and
is particularly exposed on the Ambleside road, near the seven
mile stone from Keswick.
The rocks constituting the greatest bulk of the Lake Mountains
have been commonly described under the general appellation of
slate; although many of them shew no disposition to the slaty
cleavage. They may be divided into three groups, which have been,
in a former edition called the Clayslate, Greenstone, and
Greywacké divisions; the last of which seems now to belong
to, or be included in, what Mr. Murchison calls the Silurian
System.
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