6. WEST FLORIDA LAKE REGION. 225 



6. WEST FLORIDA LAKE REGION. 

 (figure 54) 



References. Sellards 2 {^i, one sentence near bottom of page), Sellards 

 & Gunter 3 (113, 114, 115), and U. S. soil survey of the "Marianna area" 

 Two photographs of lakes in this region have been published; one by 

 C.lapp in the 2nd Annual Report of this Survey, plate 2. fier. r (reproduced 

 herewith), and again in U. S. G- S. Water Supply Paper 3ig, plate 3 B. 

 entitled "Sink hole containing pond, 10 miles southeast of Vernon, Wash- 

 ington County," and the other bv Sellards and Gunter in the 4th Annual 

 Report of the Florida Survey, plate 15, fig. i, entitled "Porter's Pond, 

 twenty miles south of Chipley, in Washington County.'' 



The boundaries of this region have not been determined except 

 at a few points, but it probably covers between 300 and 400 square 

 miles. There is nothing like it in any other state, but it bears consid- 

 erable resemblance to the peninsular lake region, described farther 

 en. 



Geology and Soils — Nothing definite is known about the geology, 

 as no rock outcrops have been observed. The prevailing soil is a 

 loamy sand, or very sandy loam, probably underlaid by clay, though 

 none of the railroad cuts seem to be deep enough to reach the bot- 

 tom of the sand. 



In that part of the region lying within the "Marianna area" of 

 the government soil survey the greater part of the soil is classed as 

 "Norfolk sand" (named for Norfolk, Va.) The following mechan- 

 ical analysis, representing the average of two localities, is taken from 

 that publication. (The localities are not specified, and may or may 

 not be in the lake region. ) The first column of percentages repre- 

 sents the soil and the second the subsoil (depths not specified). 



Mechanical Analysis of "Norfolk Sand/' Jackson County. 



Soil Subsoil 



Fine gravel (2-1 mm.) — 4.5 3.1 



Coarse sand (i-.S mm.) — 26.4 23.7 



Medium sand (.S-.25 mm.) 16.4 15.9 



Fine sand (.25-. i mm.) --__ 31.2 34.5 



Very fine sand (.i-.os mm). — __ 10.9 11.4 



Silt (.os-.oos mm.) 7.4 6.3 



Clay (.005-0 mm.) 33.9 5.2 



Total 100.7 loo.i 



It will be observed that the differences between the soil and sub- 

 soil are slight; and the same is true also of the "Norfolk coarse 



