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together occupy by far the larger portion of the earth’s crust ; the 
igneous rocks, such as we see about Borrowdale, are less extensive, 
being confined to those areas which either are or have been the 
scene of volcanic’activity. When rocks are cut into—especially 
those that have had an aqueous origin—we find that they occur in 
layers, or strata. These layers are sometimes piled one above 
another to a very great height, or underlie one another to a great 
depth. We also find that the layers vary very considerably in 
their thickness, as well as in the mode of their aggregation. For 
instance, there is a very great difference in the thickness of the 
layers composing St. Bees Head, some being only a few inches 
thick, whilst others are several feet. In the slaty rocks of Skiddaw 
the layers also vary, but not so much as the sandy rocks of 
St. Bees Head, and they are much thinner as a rule at Skiddaw. 
Again at Distington or Overend, we find similar variations in the 
thickness of the different beds of limestone. Sometimes we find 
layers of different sorts of rock alternating, as in the cliffs between 
Whitehaven and Harrington, which consist of layers of sandstone 
interstratified with shale, and an occasional seam of coal. At other 
places like St. Bees Head, we see a great number of superimposed 
layers of the same sort of rock: there it is redsandstone. Then 
again at Distington quarry there are a great many layers of another 
sort of rock—limestone ; whilst Skiddaw and Dent are made up 
almost entirely of slate. These rocky layers, sometimes, are nearly 
level ; at others they are slightly, or perhaps highly, inclined; and 
not unfrequently, especially in hilly countries, they may be seen 
standing on end. Sometimes they are bent, at others contorted, 
as if they had been subjected to a pressure endwise ; or again we 
find them broken completely across—or faulted, as it is called— 
and the layers on one side of the fault lifted away above the other. 
Most rocks, too, are greatly intersected by joints. Besides the set 
of horizontal or inclined joints separating the different beds or 
strata, there are two other sets, nearly at right angles to those and 
to each other, by which the rock is split into rhombohedrons 
varying in size and proportion with the proximity of the joints. 
In some formations, such as the Skiddaw Slate, these joints are 
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