GEOLOGY 
To put this into a briefer form, we may say that the parish boun- 
daries of Cumberland were laid out chiefly by a nation of hunters, and 
not by an agricultural people ; and that we have kept them since very 
much in the form in which they passed into the hands of the first 
Teutonic settlers. 
XIV. Tue Minerats or CumBeRLAND.—There would have been 
some advantages in treating Cumberland Minerals under the various geo- 
logical formations to which they belong ; but as this plan would fail to 
bring them, as a whole, clearly under the eye, they are given separately here. 
They may be grouped (1) in accordance with the nature of their 
bases ; (2) according to their chemical composition considered in connec- 
tion with their crystalline form ; (3) on an economic basis; or (4) with 
reference to their mode of origin. Perhaps the last of these, in an article 
dealing mainly with the geology of Cumberland, may be regarded as the 
most suitable for the purpose. The customary order of treatment is as 
follows :— 
The original Minerals of Eruptive Rocks may be taken first. These 
include Quartz and the Felspars, of which in Cumberland, Orthoclase, 
Albite, Oligoclase and Labradorite are the chief. The first three felspars 
are mainly confined to the acid eruptive rocks, and the last one is the 
usual felspar of basalts, dolerites, and of most andesites. Hornblende oc- 
curs as an original constituent of most of the granites and the rocks allied 
thereto, though never in any large proportion. It also forms one of the 
minerals of the andesites. Augite (or rather Pyroxene in one or other 
of its monosymmetric forms) is found in all the dolerites and basalts, and 
also in the andesite lavas. It also occurs sparingly in some of the 
aplite veins associated with the granitic rocks. The orthorhombic 
Pyroxenes are represented in a few basic and sub-basic eruptive rocks. 
The commonest mica is Biotite, which is an original constituent of nearly 
all the granites and the rocks allied to them, and also of the Mica traps. 
It probably occurred originally in many of the andesites. 
Mucovite, as an original constituent, is by no means of common 
occurrence. One of its chief sources being a remarkable microgranite, 
which occurs in the Ordovician rocks near Melmerby and at other places 
along the foot of the Cross Fell Escarpment. 
With these, the more important of the original constituents of the 
eruptive rocks, there also occur Ilmenite, Magnetite, Pyrites, Pyrrho- 
tite, Molybdenite, Apatite, Sphene and a few other minerals, amongst 
which may perhaps be included, Zircon and Orthite. 
Contact-metamorphism has developed a very interesting set of 
minerals, which, as might be expected, vary with the nature of the rock 
in which they occur. In rocks of argillaceous composition, the best 
known mineral of these is Chiastolite (a form of Andalusite), which 
occurs chiefly in the altered Skiddaw Slates in the zones around or over 
the granite masses. Where these Skiddaw Slates assume more the nature 
of sandstones, the chief mineral developed, especially in close contiguity 
to the eruptive rock, is Biotite. 
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