194 FLORIDA GEOLOGICAL SURVEY SIXTH ANNUAL REPORT. 



Streams. In virgin forests, especially on slopes and in valleys, there 

 is considerable humus. 



The following mechanical analyses of five typical upland. soils 

 of this region are taken from the soil survey of the "Marianna 

 area," published in the fall of 1910. (The dimensions of the seven 

 classes of soil particles are not given in that publication, but have 

 been taken from other publications of the U. S. Bureau of Soils.) 

 The first is the "Greenville clay," a reddish or brownish clay loam 

 believed to be mostly residual from the underlying limestone. The 

 second is the "Greenville sandy loam," which differs from the first 

 in being more sandy, and is believed to be derived mostly from the 

 Lafayette formation. The third is the "Orangeburg fine sandy 

 loam," a gray, brown, or reddish-brown fine sandy loam with red 

 sandy clay subsoil, both soil and subsoil usually containing many 

 small ferruginous concretions. The fourth is the "Orangeburg 

 coarse sandy loam," somewhat coarser than the preceding, as its 

 name implies. The fifth is the "Norfolk fine sandy loam," a gray 

 or light brown medium fine sandy loam with yellow sandy clay sub- 

 soil, presumably derived from the Lafayette formation, like the two 

 preceding. Percentage figures for both soil and subsoil are given 

 in the publication cited, but only those for the top soil are reproduced 

 here. 



Mechanical Analyses^ of Soils of Marianna Red Lands. 



12345 



Fine gravel (2-1 mm.) 1 1 0.9 2.8 1.2 2.3 1.0 



Coarse sand (1-.5 mm.-) 3.2 15. i 10.4 27.8 12.3 



Medium sand (.5-.2S mm.) 2.0 11.6 8.3 16.1 12.4 



Fine sand (.25-. i mm.) 13.6 31.4 35.7 24.3 37.8 



Very fine sand (.1-.05 mm.) ii.o 12.8 25.7 9.1 18.3 



Silt (.05-.005 mm.) __- 10.3 II. 7 - lo.o 8.9 10.3 



Clay (.005-0 mm.) ^_- — 59.0 14.9 8.8 11.7 7.9 



Total loo.o 100.3 loo-i icx).2 loo.o 



Very little, has been done in the way of correlating such figures 

 as these with vegetation, but presumably when other things are 

 equal the soil that has the largest proportion of fine particles has the 

 most available potassium and other minerals. 



Dr. Eugene A. Smith in the 6th volume of the Tenth Census, 

 page 197, gives the following analysis of red loam soil from the low- 

 lands of Spring Creek near Campbellton, where the principal trees 

 were hickory, sweet gum, post, red and Spanish oaks, and short- 

 leaf pine. The sample represents a depth of ten inches, and the 



