22 FOURTH REPORT — 1834. 



Their geographical position is between the supposed ancient 

 openings of the Susquehanna and Potomac rivers. No one who 

 is familiar with the annual floods of these rivers, and has seen 

 the burden of wood and trees which the former tears up in its 

 passage through the mountains, and discharges each spring into 

 the Chesapeake Bay, can doubt that the very same rivers have 

 probably been employed in olden time in forming these very 

 tracts of sand, clay, and lignite. There are now in the upper 

 part of the bay large flats, which consist solely of sand and 

 drifted timber, the annual scourings of the Susquehanna ; and 

 if we conceive these tracts to become converted into marshes 

 and swamps, as might readily happen, we have all the circum- 

 stances, and in the same district, which would be requisite to 

 produce from these recent deposits beds perfectly similar to the 

 more ancient ones just described. 



Whether those ancient alluvial deposits from Martha's Vine- 

 yard to the Chesapeake are all of one date of formation, and 

 what indeed their precise age is, are matters demanding much 

 future research to detennine. I have called these beds alluvial, 

 but by no means venture to suppose them all the results of ac- 

 cumulation in deltas, strictly so called. Our rivers may have 

 had basins or estuaries through the tracts in question, through- 

 out which, as well as upon the coast, these beds may have col- 

 lected. The details of this formation further south are not in a 

 sufficiently authentic shape to be presented ; we know, however, 

 that similar beds of clays, sands, and lignites occur largely upon 

 most of the southern rivers, and upon the Mississippi, on a scale 

 which is truly gigantic. 



I am inclined to consider as a portion of the same formation 

 an extensive group of variegated clays and sands which spread 

 themselves very widely over the States of Georgia and South 

 Carolina. Like the others before treated of, these contain few 

 fossils. They are seen to repose in some places upon the cre- 

 taceous rocks, as those in New Jersey do ; in some places upon 

 Eocene; and they are also found below the diluvium. 



These beds have been already referred by Vanuxem to ancient 

 alluvial origin. He thus describes them ; 



"The ancient alluvial is chiefly composed of red earth. This 

 earth is pretty uniform in its character, consisting of sand, with 

 a minute portion of clay, coloured by red oxide of iron. Its in- 

 ferior parts often contain pebbles, sometimes coarse nodules or 

 geodes of iron, resting almost invariably on the white or varie- 

 gated clays, or upon those masses which contain littoral shells. 

 Though not often met with beyond North Carolina, it is ex- 

 tremely abundant in all the States south of it. It appears to 



