212 GEOLOGICAL SURVEY 
5. That in South Carolina the proportion of recent species in this formation amounts to 40 per 
cent. I have, therefore, referred it to the older Pliocene. 
6. That the P. Pliocene is confined to a belt along the coast, of about eight or nine miles in 
breadth. 'The fossils are nearly all referable to living species, now inhabiting the coast: a few, 
however, belong to the Fauna of Florida and the West Indies, An elevation of the coast has 
taken place since the deposition of these beds, which, it is probable, has given the rivers of the 
Atlantic slope a western tendency. 
7. That the submerged stumps of trees, found below the level of high-tide, along the coast, are 
not the result of subsidence, properly so called, but must be referred to the encroachment of the 
sea upon the land, and to the peculiar character of the deposits in which they grew. 
8. That the almost entire absence of fluviatile shells in the recent and Tertiary deposits is 
mainly due to two facts: 1. That there is a considerable space between the line of brackish and 
salt water, where neither fluviatile nor marine forms can exist. 2. That the streams have not 
transporting power sufficient to bring down fresh water shells. So long as these circumstances 
exist, there can be no mixture of fluviatile and marine shells. 
CHAPTER VIL. 
PRACTICAL, OR ECONOMICAL, GEOLOGY. 
General views of soils—Classification of soils—Physical properties of soils——Composition of 
soils.— Composition of cultivated plants.—Manures.— Mineral manures.—Calcareous manures. 
—Marls of the State-—Effects of calcareous manures.—Rotation of crops — Draining —NSoils 
of the State-—Lime burning.— Metallurgy. Manufacture of iron—Exztraction of gold from 
its ores.— Materials used in the arts. 
Were it necessary to offer any proof of the fact that all soils derive their mineral constituents 
from the disintegration and decomposition of rocks, it might readily be found in almost every Dis- 
trict in the State, beyond the northern boundary of the Tertiary formation ; for almost every where 
the process may be traced from the subjacent solid rock to the soil upon the surface. There is 
scarcely a subject of more common observation and remark than the sudden changes that take 
place in the appearance and character of soils; and although it often escapes the notice of obser- 
vers, they are intimately connected with corresponding geological changes in the underlying rocks. 
The principal roads traverse the State from North to South, and thus pass over the upturned 
edges of the rocks. Changes and alternations of soils are, therefore, frequent, and often striking, 
in that direction. No one can avoid observing the contrast between the cold, grey soils of the clay 
