OYSTER INVESTIGATIONS IN GEORGIA 63 



the ontrancos (o the sounds are always ohsductcd with sand bars. 

 Witli the excejition of tlic di'cdtjiMl channels, the sounds for the most 

 pait are shallow. The chaiacter of (he bottom varies in diU'erent 

 localities, but is generally shiftin*; sand. The salinity of water is 

 rather hifjh near the entrances, gradually decreasing toward the 

 mouths of the rivers. The sounds are ex[)osed to heavy northeast 

 seas from the ocean. 



RIVERS 



I St Marys, Satilla, Alfanialia, Daiicii, Ogccclicc, Savaniiali. Si-c li-s. 1 utkI L' | 



On the basis of their origin, i-ivei-s of the State of (ieorgia empty- 

 ing into the Atlantic Ocean fall into two classes: Those originating 

 hi the Piedmont Plateau and Appalachian Mountains, such as the 

 Savannah, Ogeechee, and Altamaha Rivers; and those having their 

 source within the coastal plain, such as Satilla and St. Marys. 'Jlie 

 rivers of the first class have larger drainage areas, are longer, and 

 carry greater volumes of water. With the exception of the Ogeechee 

 Kiver, which throughout a greater part of its course lias much the 

 aspect of a stream of the second class, their waters are muddy, con- 

 taining a considerable amotmt of sediment derived from red clay 

 hills of the Piedmont Plateau. The rivers of the second class are 

 smaller ; they flow wholly through areas where the geological forma- 

 tions are predominantly sand, and, therefore, their waters are clear 

 but dark, or even black, from dissolved organic matter. 



The bottoms of the rivers vary greatly, ranging from verv soft 

 mud to hard mud and shifting sand. The water near the niouths 

 is always brackish but subject to great fluctuations, depending on 

 the stage of the river and tide. At the time of freshets such as 

 occurred in January and February, 1925, entirely fresh Avater was 

 found as far as the clubhouse near "the entrance of Altamaha Sound. 

 On the other hand, at low stage during the dry season the salinitv 

 increases, approaching the degree characteristic of the open ocean. 

 Tidal currents are strong in the rivers and reach a velocitv of 

 several knots at ebb tide. 



INLARSHES AND CKEEKS 



A continuous network of small creeks, tidal rivers, estuaries, and 

 salt marshes is a characteristic feature of the coast. The area of 

 salt marshes probably does not aggregate more than 150 oi- 200 

 square miles; but since no survey of the marshland of the State has 

 yet been made, accurate figures are not available. The character of 

 the bottom represents all the graduations from extremely soft mud 

 to hard mud and clay, while sand occurs here very rarely. Tlie 

 bottom is often covered with pieces of marsh grass mixed with 

 either clay or mud, making a relatively hard substratum. The 

 sahnity of the water varies in different localities, but its fluctuations 

 are not as great as in the mouths of the large rivers. The tides, 

 that create strong currents in the sounds and rivers, flow rather 

 ;lowly in the creeks and marshes but provide an exchange of water 

 iulRcient to prevent stagnation. 



