56 
FLORIDA GEOLOGICAL SURVEY—FOURTH ANNUAL REPORT. 
agent of transportation of soils, however, is water, the amount of 
soil transported by water being much greater than that of all other 
factors combined. 
CLASSIFICATION OF SOILS. 
A satisfactory classification of soils is difficult and the subject 
may be approached from any one of several different standpoints. 
A common system of general classification is that in which the soils 
are classified in accordance with their manner of formation, as 
residual, transported, or colluvial. 
RESIDUAL SOILS. 
The residual soils are those which have formed in place. In this 
class of soils the parent rock from which the soil is derived lies 
beneath the surface at a variable depth, depending upon the inten¬ 
sity and duration of the weathering processes and upon the surface 
contour. On steep slopes little or no soil accumulates, being removed 
by surface wash. On the more gentle slopes if the weathering pro¬ 
cesses have been long continued soil may accumulate to a great 
depth. The residual soils partake to some extent of the character¬ 
istics of the formations from which they are derived. Thus a sandy 
formation upon decay gives rise to sandy soils. Clays give rise to 
clay soils. The chemically complex rocks such as the granites and 
other igneous rocks give rise to soils which include a variety of min¬ 
erals. Limestones are largely dissolved in the processes of soil 
formation, the resulting soils being formed almost entirely from the 
impurities which the limestones contained. 
The typical residual soils are those which have formed from the 
decay of igneous rocks. Such soils possess certain distinctive char 
acteristics due to the fact that they are formed from rocks that are 
chemically and mineralogically complex, and from the fact that the 
soil materials have in no stage been subjected to the assorting power 
of wind or water. Those soils which have formed in place from 
sedimentary rocks are here designated as residuo-sedimentary. 
RESIDUO-SEDIMENTARY SOILS. 
The residuo-sedimentary soils differ from the typical residual 
soils in that they are derived from rocks the materials of which in 
a previous stage of disintegration were more or less perfectly as¬ 
sorted by wind or by water. To this extent the residuo-sedimentary 
