Page:Popular Science Monthly Volume 3.djvu/236

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226
THE POPULAR SCIENCE MONTHLY.

from 12 feet to 20 feet, in consequence of the deposition of solid matter caused by the diminished motion of the river.[1]

In conclusion, we may say a word regarding the proximate future of Niagara. At the date of excavation assigned to it by Sir Charles Lyell, namely, a foot a year, five thousand years will carry the Horseshoe Fall far higher than Goat Island. As the gorge recedes, it will drain, as it has hitherto done, the banks right and left of it, thus leaving a nearly level terrace between Goat Island and the edge of the gorge. Higher up it will totally drain the American branch of the river, the channel of which in due time will become cultivable land. The American Fall will then be transformed into a dry precipice, forming a simple continuation of the cliffy boundary of the Niagara. At the place occupied by the fall at this moment we shall have the gorge enclosing a right angle, a second whirlpool being the consequence of this. To those who visit Niagara five millenniums hence, I leave the verification of this prediction; for my own part, I have a profound persuasion that it will prove literally true.

 

STATE GEOLOGICAL SURVEYS.
By Prof. ALBERT E. LEEDS,

OF THE STEVENS INSTITUTE OF TECHNOLOGY.

A STRENUOUS effort is being made at the present time to reorganize the Geological Survey of Pennsylvania. It promises to be successful. The legislators of that State, in voting upon the measure, will be mainly influenced by considerations relating to the pecuniary value of a geological survey in locating beds of coal, building-materials, and ores. But the educated public will desire to know, in addition to these matters, what influence such a geological survey will have upon the intellectual activity of the community at large, and how great an amount of scientific bustle it will create in the museums and laboratories of institutions of learning.

A very satisfactory answer can be given to the first of these queries, after reviewing the scientific periodicals and journals of learned societies in this country, during the last half-century. It will be seen that the desultory descriptions of plants, birds, and the external characters of minerals, which constituted a large portion of the scientific literature at the beginning of this period, gave place to laborious analyses, and to elaborate articles on geological phenomena. Many of the most valuable contributions to science during this epoch consisted in reports of the geological surveys then in progress, or in-

  1. Near the mouth of the gorge at Queenstown, the depth, according to the Admiralty Chart, is 180 feet; well within the gorge it is 132 feet.