Page:Popular Science Monthly Volume 67.djvu/681

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FRESH-WATER SPRINGS IN THE OCEAN.
675

who were crowded forward so furiously that they were precipitated down this pali of a thousand feet, where their bones could be seen till quite recently. This pali is one of the most interesting sights visited by modern tourists.

The Pliocene Tertiary.

These are quite extensive plains near the sea level composed partly of sediments derived from the decay of the basalts and other igneous products, and partly of calcareous marine deposits. "Without attempting precision of delimitation, our map presents an approximate contour line of 500 feet altitude, which may represent the upper border of the terrane, which is clearly proved by its fossils to belong to the Pliocene

Fig. 2. Erosion on the Waianae side of kaala.

Tertiary.[1] This band has a very variable width, dependent upon the amount of subaerial erosion, being the most extensive in valleys like those of Waianae and Waimanalo and in the more open area between the two mountain ranges. It is upon these plains that several large sugar plantations have been installed, for whose benefit numerous artesian wells have been sunk. In the southern part of Oahu there is a continuous belt of cane-fields eighteen miles in length, and averaging two in breadth to the west of the city of Honolulu. Others are near Waianae and Waialua.

The sugar plantations were at first located upon other islands of the group, as on Kauai, Hawaii and Maui, where plenty of streams of water afford plentiful supplies for moistening the soil, or to trans-


  1. W. H. Dall, Bulletin Geol. Soo. America, Vol. XI., p. 57.