8 FOURTH REPORT 1834. 



ber of the rivers, the magnitude of the coast, and the enormous 

 lakes where freshwater deposits are probably accumulating on 

 a scale of great extent. 



Alluvial Deposits. — From the mouth of St. Croix River to 

 Florida Point, the length of the Atlantic coast is about 1800 

 miles ; and along the Gulf of Mexico, from Florida Point to 

 Sabine Ri\er, the boundary of the United States coast, the di- 

 stance is 1100 miles more. The first section receives the rivers 

 which descend the Atlantic slope. The several basins drained 

 by these rivers, according to the view given by Darby, are 

 forty-two in number, and the total area drained is 252,900 

 square miles. 



The smaller river bashis in the vicinity of the delta of the 

 Mississippi, from Sabine River to the western slope of Florida 

 inclusive, are, excluding the great basin of the Mississippi, six- 

 teen, with an area of 144,240 square miles. The area drained by 

 the Mississippi and all its tributaries is computed at 1,099,000 

 square miles. I do not extend the survey to the many large 

 rivers which enter the gulf west of the Sabine. The quantity 

 of sediment conveyed to the ocean from so wide an area must 

 be ven,' enormous ; and, as a proof, we behold either an alluvial 

 'delta or a bar at the mouth of almost every river. The entire 

 line of sea-coast, from the Sabine to the mouth of the Pearl, 

 presents an uninterrupted marsh 400 miles long, and from 30 

 to 50, or even 70 miles wide, the production solely of the Mis- 

 sissippi and the rivers adjacent. From the mouth of the Pearl 

 eastward, the sandy pine tract reaches the gulf, and extends, 

 with little interruption, along the whole sea-coast of the Missis- 

 sippi, Alabama, and great part of Florida. Along this part of 

 the gulf, and along the Atlantic from the point of Florida to 

 New Jersey, though many extensive marshes occur upon the 

 coast, the shore is more generally sandy. At the mouths, how- 

 ever, of nearly all the rivers, low, marshy, alluvial tracts are to 

 be seen. Low down, towards their mouths, these rivers run 

 through extensive flats or meadows, most of which are at pre- 

 sent elevated above the highest spring-tides, though it is pos- 

 sible that many of them, during unusually heavy storms or 

 great freshets, may be liable to be partially submerged. These 

 meadows are often several miles in width, and bordered on each 

 side by abrupt banks, consisting of the solid strata of the coun- 

 try, so that they have all the aspect of having been, at a former 

 period, permanently beneath the tides, which, on this suppo- 

 sition, penetrated their valleys in the shape of extensive bays 

 ;ind estuaries. 



The river meadows are never covered bv the coating of 



