88 FLORIDA GEOLOGICAL SUR\TEY-I3TH ANNUAL REPORT

The portion northwest of the Suwannee River was described in the 6th Annual Report, pages 3Q2-309, and a few of the vegetation types in Sumter County in the 7th.

















 Fig. 6. Hydro-electric power-house with 20-foot dam (built in 1911), oil \Vithlacoochee River about 10 miles below Dunellon. March 4, 1915.

 Topography and Gcology. The region is mostly flat and less than 75 feet above sea-level, and is underlaid throughout with a hard limestone (Oligocene), that is exposed in innumerable boulderlike or larger outcrops.* There are occasional irregular low sandy ridges, scarcely distinguishable from parts of region No. 4, where the depth to the rock is unknown. The coast is unlike any other oi equal extent in the world, as far as known, in being bordered by marshes instead of sandy beaches; the reason being apparently that the slope of the ocean bottom here is so gentle as to practically eliminate wave-action on the shore, just as if there was a barrier beach a few miles off shore. Stern-wheel steamers from the Suwannee River ply the open Gulf from the mouth of that river to Cedar Keys. The same limestone rock that characterizes the region is said to crop out on the bottom of the Gulf some distance out. Some of the rivers have rocky shoals a few miles from their mouths, and the one on the Withlacoochee is utilized for power purposes.

 *See fig. 5. The soKI survey of Hernando County shows one solid area of rock outcrop in the eastern end of the county covering about half a square mile.