474 THE POPULAR SCIENCE MONTHLY. 



Significant of this was the feeling of the American people during 

 the fearful droughts a few years since in the States west of the Mis- 

 souri. No days were appointed for fasting and prayer to bring rain 

 there was no attribution of the calamity to the wrath of God or the 

 malice of Satan ; but much was said regarding the folly of our people 

 in allowing the upper regions of their vast rivers to be denuded of 

 forests, thus subjecting the States below to alternations of drought 

 and deluge. Partly as a result of this, a beginning has been made of 

 teaching forest-culture in many schools, tree-planting societies have 

 been formed, and " Arbor-day " is recognized in several of the States. 

 A true and noble theology can hardly fail to recognize in the love of 

 Nature and care for our fellow-men thus promoted, something far 

 better, both from a religious and a moral point of view, than any 

 efforts to propitiate the Divine anger by flattery, or to avert Satanic 

 malice by f etichism. 







THE FALLS OF THE MISSISSIPPI. 



By JOHN AENOLD KEYES. 



THE Mississippi River and its tributaries, forming as they do one of 

 the most important river systems on the globe, and draining one 

 of the most richly-furnished continental areas, present, moreover, many 

 interesting geological studies, and open up fields of curious inquiry 

 to the investigator. The old discussions as to the possibility or im- 

 possibility of things has, for the most part, passed out of existence in 

 this department of science. No one now denies the general principles 

 of geology as at present taught; therefore new regions of investigation 

 are to be approached on the firm foundation of the old, and difficult 

 matters settled in conformity with established principles. That there 

 is no new thing under the sun is a saying well worn, but in one sense 

 correct, yet the same thing recognized as a fact in one situation may 

 under other circumstances seem a fallacy. The Falls of Niagara are 

 familiar to all, and came to exist through causes natural and easy of 

 explanation, inasmuch as the whole secret lies in the character of the 

 formations over which the river flows, viz., a crust made up of from 

 sixty to one hundred feet of comparatively hard limestone lying in a 

 nearly horizontal position, beneath which is a deep deposit of shales 

 and sandstones. Whenever the river in wearing its channel back 

 reached the point where this arrangement of rocks began, the hard 

 limestone would naturally resist the erosive action of the waters, while 

 the underlying shales and sandstones, offering less resistance, would be 

 rapidly cut away, until a vertical fall such as is now seen would be 

 the result, with a constant recession going on, leaving b,elow the broad 

 canon, walled on either hand by bluffs, the crests of which are pre- 

 served by the limestone crowning them. 



