>9"1 STEVENSON— FORMATION OF COAL BEDS. 543 



struction, the forests do not appear to have been seriously disturbed by 

 floods." 



An observation by McGee^** is in place here. The Mississippi, 

 as it flows past northeastern Iowa, meanders through a densely 

 wooded floodplain, four or five miles wide, now in one main and 

 half a dozen subordinate streams and yet again in numerous large 

 and small channels. But this plain is flooded each year ; according 

 to writers already cited, the river at times covers the whole plain 

 from blulif to blufi^ as a rapid stream. 



Lyell,^'' in referring to the 1844 crevasse near New Orleans, savs 

 that the water poured through at the rate of ten miles an hour, inun- 

 dating the low cultivated lands and sucking in several flat boats, 

 which were carried over " the watery waste " into a dense swamp 

 forest. He mentions that the great Carthage crevasse was open 

 during eight weeks and that nothing was visible above the flood 

 except the tops of cypress trees growing in the swamp. 



Humphreys and Abbot-'' state that the bottoms of the Illinois 

 river are two to ten miles wide and raised only a few feet above the 

 usual level of the river. The greatest part of this swampy country 

 is included in the "American bottom." The Kaskaskia flows with 

 crooked course through a heavily wooded alluvial bottom, over- 

 flowed eight or ten feet by freshets. These authors emphasize the 

 fact, too often ignored, that lowland areas are usually well soaked 

 by rains preceding the floods and the swampy areas become covered 

 with water, so that when the overflow^ comes, it finds everything 

 prepared for resistance. 



Lyell-^ had the weird experience of descending the Alabama 

 river in time of high flood. At night the passengers were startled 

 by crashing of glass and partial destruction of the steamer's upper 



''W J McGee, "Pleistocene History of Northeastern Iowa," Eleventh 

 Ann. Rep. U. S. Geo!. Survey, 1891, p. 204. 



" C. Lyell, " Second Visit to the United States of North America," Lon- 

 don, 1850, Vol. II., p. 169. 



^ A. A. Humphreys and H. L. Abbot, " Report upon the Physics and 

 Hydraulics of the Mississippi River," Reprint, Washington, 1876, pp. 38, 66, 

 76, 82. 



-'C. Lyell, "Second Visit," etc., Vol. II., pp. 51, 141. 



141 



