The eastern part of this parish consists of granite, forming a portion
of an extensive group of this rock, in which are situated Roughtor and
Brown Willy, the highest hills in Cornwall. This granite is of the
ordinary kind, large grained, and often porphyritic. It contains beds
of fine-grained rocks, in some of which crystalline felspar, quartz,
and mica, constitute the entire mass; but in others these minerals are
embedded in a basis of compact, or rather of granular felspar, which
is itself apparently a compound of felspar and quartz. The junction of
the granite with slate is concealed by a large track of marsh and bog;
adjoining to which is a dreary waste of common, resting on an
irregular bed of quartzose gravel, derived from the granite hills, and
evidently of diluvial origin. This eastern part is sterile, merely
affording a scanty subsistence to cattle during the summer. The
remainder of the parish is composed of felspar and hornblend rocks,
traversed here and there by courses of granitic elvan, a rock in every
respect similar to that occurring in the granite. One of these courses
may be seen by the road side near the rivulet of Pencarrow. Here the
country is wooded and cultivated, exhibiting some picturesque scenes
of hill and dale; so characteristic of the hornblend rock near granite.
[2] See Mr. Whitaker’s remark on this etymology, hereafter
under the parish of Lesnewth.
[3] Jewell contra Harding, p. 582.
[4] In the Exchequer 61_l._ 17_s._