MANUAL OF NATURAL HISTORY. 585 



the natatorial Lams, Anser, and Colymbas, be- 

 sides the raptorial Vultur and Aquila, and the 

 insessorial Motacilla, Anabates, Hirundo, and Ca- 

 primidgus. In the caverns of Brazil remains of 

 scansorial birds, Goccyzus, Picus, and Psittacus, 

 and the cursorial Rhea, a bird allied to the Ostrich, 

 have been discovered. 



V. CLASS.— QUATERNARY-FORMATIONS. 



In the Drift, or Superficial Accumulations, we 

 find the present era represented ; the beds of gravel, 

 sand, coral-reefs, and peat-moss, being of recent for- 

 mation, by the agency of floods, irruptions of the 

 sea, and the action of rivers, glaciers, and icebergs. 

 When the remains of plants and animals occur, they 

 are found to belong to those of existing species. 



I. Group. — Alluvial Deposits. 



These deposits are produced by the ordinary ac- 

 tion of water, and are formed of sand, gravel, and 

 clay. The study of these recent or alluvial deposits, 

 such as the extension of the deltas at the mouths of 

 rivers ; the receding or encroaching of the sea ; vol- 

 canic disturbances ; the mud and gravel deposited 

 in their course by rivers and torrents, are all im- 

 portant, as shewing the nature of the changes on 

 the earth's surface that occurred in ancient epochs. 

 Raised Beaches are produced by the action of the 

 sea, by depositing new matter so as gradually to 

 increase the coasts, as in Guadaloupe, where human 

 remains have been imbedded ; or they are the re- 



o c 5 



