Page:Geology and Mineralogy considered with reference to Natural Theology, 1837, volume 1.djvu/19

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Hence it appears that the numerical amount of our population, their varied occupations, and the fundamental sources of their industry and wealth, depend, in a great degree, upon the geological character of the strata on which they live. Their physical condition also, as indicated by the duration of life and health, depending on the more or less salubrious nature of their employments; and their moral condition, as far as it is connected with these employments, are directly affected by the geological causes in which their various occupations originate.

From this example of our own country, we learn that the same constituent materials of the earth are not uniformly continuous in all directions over large superficial areas. In one district, we trace the course of crystalline and granitic rocks; in another, we find mountains of slate; in a third, alternating strata of sandstone, shale, and limestone; in a fourth, beds of conglomerate rock; in a fifth, strata of marl and clay; in a sixth, gravel, loose sand, and silt. The subordinate mineral contents of these various formations are also different; in the more ancient, are veins of gold