Page:Popular Science Monthly Volume 67.djvu/689

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683
FRESH-WATER SPRINGS IN THE OCEAN.

himself upon the 'Hydrology of Cuba' in the Water Supply Paper No. 110, page 93: the springs "issue at all altitudes, from the higher portions of the hills down to the lowland border, or even at sea level. . . . Not all the water comes to the surface as springs, but some passes outward and emerges from the sea bottom along the coast, where in many instances the fresh water can be seen bubbling up through the salt water. Such springs occur in Havana Harbor and at many other points. The fresh water which surges as copious springs on some of the keys is probably of the same origin, coming from the mainland through subterranean passages in the limestone."

These may be an illustration of the derivation of fresh water from the mainland upon the island of Nashawena in Buzzards Bay Massachusetts. This is a large island midway between New Bedford and Marthas Vineyard, upon which it is proposed to erect a new state prison as well as a leprosarium. Near the center of the island and very high up is Menaud Pond, a splendid body of pure fresh water, capable of furnishing an ample supply to the new institutions. There is no perceptible inlet or outlet; the supply seems to be derived from springs, such as may be conceived to originate upon the mainland, to pass beneath the bay and to rise to the surface at the summit of Nashawena. Except for the accidental presence of land here this stream would have risen to the surface in the midst of salt water. People familiar with the shallows over the region between Long Island and the Great Banks of Newfoundland speak of an 'underground river' extending from Labrador to Block Island having many outlets similar to the supposed one at Menaud Pond. Our theory of a connection with the mainland through Tertiary strata is a better one.

 

Conclusions.

The foregoing facts warrant us in believing in the existence of fresh-water springs bubbling up through the brine of the ocean. They are known to exist among the Hawaiian and West India islands and off the coast of Florida. The necessary conditions seem to be those which will permit the existence of underground streams flowing towards the sea; such as will render the boring of artesian wells successful. Evidently there must be strata—whether of the later fossiliferous rocks or igneous sheets—dipping gently seawards; and the springs can not appear very far away from the coast. We should, therefore, look for these phenomena adjacent to islands and all coasts bordered by Tertiary and basaltic rocks. They may be seen off nearly the entire eastern coast of the United States—from Cape Cod to the Rio Grande. Possibly also fresh water may be able to accumulate beneath the submarine belt of Tertiary between Nantucket and the Great Banks of Newfoundland. It is conceivable that they might be utilized for the supply of steamships in places where the local supply is either defective or unwholesome.