OSCILLATIONS OF CONTINENTS.

Western Star, Issue 1349, 27 April 1889, Page 2 (Supplement)

OSCILLATIONS OF CONTINENTS.

As the Continents sink down into or rise above the level of the sea, in their ceaseless oscillations, each movement is attended by a great variation in the energy with which the streams act upon their surface. If our Continent should rise a hundred feet in its southern parts the Mississippi river would immediately begin to flaw with greater swiftness, and so too all the streams which are tributary to it would have their energy enhanced up to the foot of their mountain torrents. On the other hand, if the Continent sank down a hundred feet, all these streams would at once become less effective agents of erosion and transportation, We thus see that all the erosion work of the land is to a greater or less extent determined by what is called the principle of base level of erosion. This principle, first distinctly suggested by J. W, Powell, has been amplified by other American geologists, and has served to bring into clear light the peculiar sensitiveness of our streams to the position of the sea or of hard ;

layers in the rocks which control the inclination of their stream-beds.—From “ Rivers and Valleys,” by Professor Shaler, in Scribner’s Magazine.