Page:Physical Geography of the Sea and its Meteorology.djvu/292

266 the mica in another, and the quartz in a third, and then the three brought together by some mighty power, and welded into the granite rock for the everlasting hills to stand upon? or were they, as they were formed of the chaotic matter, made into rock? Sea water is composed of oxygen and hydrogen, and its salts, like the granite, also consist of gases and volatile metals. But whether the constituents of sea water, like those of the primitive rocks, were brought together in the original process of formation, and united in combination as we now find them in the ocean, or whether the sea was fresh "in the beginning," and became salt by some subsequent process, is not material to our present purpose. Some geologists suppose that in the Chalk period, when the ammonites, with their huge chambered shells, lived in the sea, the carbonaceous material required by these creatures for their habitations must have been more abundant in its waters than it now is; but, though the constituents of sea water may have varied as to proportions, they probably were never, at least "since its waters commenced to bring forth," widely different from what they now are. It is true, the strange cuttle-fish, with its shell twelve feet in circumference, is no longer found alive in the sea: it died out with the Chalk period; but then its companion, the tiny nautilus, remains to tell us that even in that remote period the proportion of salt in sea water was not unsuited to its health, for it and the coral insect have lived through all the changes that our planet has undergone since the sea was inhabited, and they tell us that its waters were salt as far back, at least, as their records extend, for they now build their edifices and make their habitations of the same materials, collected in the same way that they did then, and, had the sea been fresh in the interim, they too would have perished, and their family would have become extinct, like that of the great ammonite, which perhaps ceased to find the climates of the sea, not the proportion of its salts, suited to its well-being.

495. Cubic miles of sea salt.—Did any one who maintains that the salts of the sea were originally washed down into it by—the rivers and the rains ever take the trouble to compute the quantity of solid matter that the sea holds in solution as salts? Taking the average depth of the ocean at three miles, and its average saltness at 3½ per cent., it appears that there is salt enough in the sea to cover to the thickness of one mile an area of several millions of square miles. These millions of cubic miles of crystal salt