GEOLOGY 
of the Carrock Fell Rock are therefore here treated as partly of meta- 
morphic origin. 
There is a large class of other minerals occurring in Cumberland 
which are due to another cause. These embrace most (but not all) of 
the original contents of mineral veins. Quartz veins, so abundant amongst 
the older rocks of Cumberland, are here assumed to be due to the slow 
dissolution of the rock by heated alkaline waters, and by the equally slow 
deposition of silica in the place of the material removed. In a few cases 
it may possibly be true that the quartz fills a pre-existent fissure or cavity ; 
but the evidence that such has been the case has not yet been satisfactoril 
made out. In the case of the great quartz vein known as the ‘ Great 
Sulphur Vein’ of the Alston district, the evidence of the quartz having 
replaced limestone is clear enough. Curiously enough in this case rocks 
other than those that are calcareous are left unaffected. Other mineral 
veins are here regarded as due to successive deposits of mineral matters 
originally held in solution in hot springs, from which the various sub- 
stances have been left at the horizon where the temperature of the walls 
of the veins coincided with the depositing temperature of the particular 
substance in solution. To this category belong most of the Galena, Chal- 
copyrite, Blende, Mispickel, Barytes, Fluor and some few other minerals 
associated with them, such as some of the rarer ores of the Caldbeck 
Fells. Even the Graphite of Borrowdale may be due to this cause. It 
may be an ultimate product of what was formerly some metallic carbide. 
All of these minerals just mentioned are here regarded as hypogenic in 
origin. There is another class of substances occurring in the mineral 
veins of Cumberland which are due to the downward percolation of cold 
surface-water, which usually contains Carbonic Acid or some of the 
organic acids allied thereto. In referring to the origin of these the cor- 
relative term epigenic is used. These surface-waters give rise to a series 
of complex changes, by which the sulphides are converted into carbonates, 
sulphates, mixed carbonates and sulphates, phosphates, etc. The varied 
contents of the celebrated mineral veins of the Caldbeck Fells, and other 
areas near Keswick, as well as those of the almost equally celebrated 
mineral veins of the Alston district, are largely due to this ‘ebbing’ of 
the original contents of the veins. Most Calcite veins are due to the 
same cause. 
To yet another series of changes of a geological nature are the New 
Red minerals due: Rock Salt, Gypsum and Anhydrite, Dolomite, Chaly- 
bite, Hematite, and some of the ores of Manganese. The origin of these 
has already been noted in connection with the Red Rocks themselves. 
It may again be mentioned here that all the Hematite deposits of 
Cumberland are replacement products of some form of calcareous matter, 
which is usually either Calcite or Dolomite. This fact has long been 
known to the officers of the Geological Survey ; but it is mainly to the 
researches of Mr. J. D. Kendall that the public are indebted for their 
chief knowledge of the facts connected with the geognostic relations of 
Hematite. It may be remarked, ponte: that the presence of pebbles 
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