176 FLORIDA GEOLOGICAL SURVEY-13TH ANNUAL REPORT

gions, and limited areas in all the others. They vary in color from white to (lark gray or nearly black, usually without any trace of red, yellow or brown. In many places shallow cuts or ditches reveal a stratum of "hardpan" (sand cemented together by some dark brown organic substance with perhaps a ,trace of iron) within two or three feet of the surface, and borings made by soil investigators seem to indicate that this is present in practically all our flatwoods areas, .unless clay or rock takes its place. The hardpan is relatively impervious to water and not readily penetrated by tree roots, but in some places it is said to be only a few inches thick, with white sand below it, so that it can be perforated by blasting or otherwise in preparing the land for agricultural purposes.
 The. damp sandy flatwoods soils are classed in the government reports as "Portsmouth fine sand," "Leon fine sand," "Norfolk fine sand, flat phase," "Fellowship fine sandy loam," etc. In the following tables they are represented by mechanical analyses 19 and 20 and chemical analysis Y. Salamanders are found only in the driest spots, and other burrowing animals are scarce.
 The whitest of the damp sand has a vegetation nearly all evergreen, something like that of the upland scrub, and this might be called low scrub. Most of it, however, has a low pine land or flatwoods vegetation, consisting mostly of pine and saw-palmetto. Within a few miles of the. larger rivers, particularly south of latitude 290, the pines may be absent over many square miles, making palmetto prairies; and sometimes the palmetto too is wanting or nearly so, but that probably indicates a dif ferent kind of soil, either w'et or marlv, or both.
 A great deal of the damp sand is too wet for successful agriculture until artificially drained, but its level topography facilitates the control of irrigation water and fertilizers, and some very intensive farming is carried on in places convenient to transportation lines.
 Sandy and rocky soils. In the Gulf hammock region the sand seems to be underlaid at no great depth by limestone, and the rock crops out in many places, sometimes thickly enough to interfere seriously with plowing. This type is designated in the soil surveys as "Leon sand," "Leon fine sand," Portsmou.th fine sand," "Gainesville sandy loam, pine woods phase,' "Hernando fine sandy loam,-