646 



DYNAMICAL GEOLOGY. 



called fluvio-marine formations. Great streams, like the Amazon, 

 carry their muddy waters hundreds of miles into the ocean ; but 

 far the greater part of the detritus, even in the case of the largest 

 rivers, is beaten back by the waves on soundings and by the shore- 

 currents, and either falls over the bottom or is thrown upon the 

 coast near by. In floods, the river-water of the Mississippi is dis- 

 tinguishable in the Gulf at the distance of only twenty or twenty- 



five miles from the bar ; in low water, at the distance of five or ten 

 miles. (Humphreys & Abbot.) 



The eastern North American coast, from Texas to Florida, and 



