QUATERNARY DErOSITS 507 



Behind the beach is a broad country of swamps. No hills arc in sight. 

 Within several miles of the mouth, the Prinzapulca River has scarcely 

 any banks, properly so called, as a rise of 1 or 2 feet would carry the 

 water over into the swamps. In going inland the first high land reached 

 is said to be the "Pine Ridge," lying between the Prinzapulca and Grand 

 rivers, reached about 60 miles up the former and 20 miles up the latter. 

 Another section of "Pine Ridge" country is said to lie between the Ban- 

 bana and Wava rivers. At Bluefields the low hill country of igneous 

 rocks (much of which resembles an altered rhyolite, some andesite tuff 

 much altered, and other dark-colored rock may be basalt) comes out to 

 the very edge of the Caribbean Sea, but the great delta country appears 

 north of the bluff. 



MODERN ALLUVIUM 



This includes the deposits in the broad delta region along the coast 

 and the younger floodplain deposits in the valleys extending back into 

 the mountain region. It is predominantly a brown sand, varying to silts 

 and claj^s near the coast and gravels in the mountains. The beach de- 

 posits and the deep red soil of the hilly country are referable to the same 

 epoch, though the soil is the result of processes that have been con- 

 tinuous throughout the Quaternary era at least. 



SOUL ALA FORMATION 



In the valley of the Wanks River there is evidently an older alluvium, 

 characterized by variegated silts and clays, with a little associated gravel 

 and sand. At Soulala it is distinctly higher than the Modern alluvium, 

 but farther down the river can not be distinguished as a topographically 

 separate floodplain. It is probably of about the age of the Wisconsin 

 drift sheet in the United States. Black carbonaceous layers may suggest 

 a cooler climate during its formation, but there is nothing else about it 

 to indicate extensive glaciation in the upper portion of the river's basin 

 during its deposition. However, the supposed glaciation may have cor- 

 responded in age with an epoch of erosion and not deposition in the 

 lower portion of the basin. 



8ACLIN FORMATION 



Pine evidently grows on several formations, but there can be little 

 question that the so-called Pine Ridge country owes its distinctive char- 

 acters largely to a deposit of fine white gravel that is distributed north 

 and south across the country as a fringe to the mountainous interior, 



