Page:Physical Geography of the Sea and its Meteorology.djvu/68

 42 stones, and gravel brought down upon these bergs are here deposited. Captain Scoresby, far away in the north, counted at one time five hundred icebergs setting out from the same vicinity upon this cold current for the south. Many of them, loaded with earth, have been seen aground on the Banks. This process of transferring deposits from the north for these shoals, and of snowing down upon them the infusoria and the corpses of "living creatures" that are brought forth so abundantly in the warm waters of the Gulf Stream, and delivered in myriads for burial where the conflict between it and the great Polar current (§ 89) takes place, is everlastingly going on. These agencies, with time, seem altogether adequate to the formation of extensive bars or banks.

117. Deep water near.—The deep-sea soundings that have been made by vessels of the English and American navies (Plate XI.) tend to confirm this view as to the formation of these Banks. The greatest contrast in the bottom of the Atlantic is just to the south of these Banks. Nowhere in the open sea has the water been found to deepen so suddenly as here. Coming from the north, the bottom of the sea is shelving; but suddenly, after passing these Banks, it dips down by a precipitous descent to unknown depths—thus indicating that the débris which forms the Grand Banks comes from the north.

118. The Gulf Stream describes in its course the path of a trajectory.—From the Straits of Bemini the course of the Gulf Stream (Plate VI.) describes (as far as it can be traced over toward the British Islands which are in the midst of its waters) the arc of a great circle nearly. Such a course as the Gulf Stream takes is very nearly the course that a cannon-ball, could it be shot from these straits to those islands, would follow.

119. Its path from Bemini to Ireland.—If it were possible to see Ireland from Bemini, and to get a cannon that would reach that far, the person standing on Bemini and taking aim, intending to shoot at Ireland as a target, would, if the earth were at rest, sight direct, and make no allowance for difference of motion between marksman and target. Its path would lie in the plane of a great circle. But there is diurnal rotation; the earth does revolve on its axis; and since Bemini is nearer to the equator than Ireland is, the gun would be moving in diurnal rotation (§91) faster than the target, and therefore the marksman, taking aim point blank at his target, would miss. He would find, on