1913] JOHNSON—COASTAL SUBSIDENCE 455 
through others whose broad spreading roots were half undermined, 
thus allowing the trees to incline forward and sink toward the 
lower level, to still others which had been wholly undermined and 
had tipped back to a nearly vertical position, standing erect but 
dead in the salt water. These trees later break off at the water 
line and give upright submerged stumps. The fact that dead 
trees and submerged stumps are often produced in this manner was 
clearly recognized by Tuomey” in his interesting report on the 
geology of South Carolina. This same author" likewise emphasized 
the fact that many so-called submerged stumps are merely ta 
roots of certain trees which descend to a great depth. The loblolly 
pine has a tap root as large as its trunk which runs down 2 or 3 
meters, and then sends off smaller roots. A forest of such trees 
growing on a low coast may be es 
attacked by the waves, and as 
the earth is removed the trees 
die and finally break off at or 
below water level. In this way 
deeply submerged ‘‘stumps”’ are 
produced which will seem to the . a a se od ang 
ordinary observer a convincing from normal retrogression of the shore 
proof of subsidence.” Fig. 2 is jine. 
a diagrammatic representation ; : 
of several stages in this process, which we found particularly well 
shown in the ‘Sea Islands” of Georgia. 
Where the sea is cutting into the “Black Bank,” a peat pe 
near Cascumpeque Harbor, many stumps had been washed out 0 
the bog, transported by waves and currents some little aan 
and left stranded, often in an upright position, on the beach an ; 
in the shallow water of the bay. Submerged stumps, due to a ae 
rise of the high tide level, to the compression of peat bogs ca : 
by a lowering of the ground-water level as the waves cut into t : 
shoreward side of such bogs (fig. 3), to the compression nc cie 
Columbia. 1848. 





 TyomEy, M., Report on the geology of South Caren 
P. 194. 
* Op, cat, 195: 
= Lyet. Cuar es, A second visit to the U.S. of 
1850. 1:316-317. 
North America. 2d ed. London. 

