1. .MARIANNA RED LANDS. 



(figures 12, 41, 42) 



References- Matson & Clapp (57), Matson & Sanford (^77, 327-329) j 

 E, ,A. Smith 2 (196-197, 218), J. D. Smith, and U. S. soil survey of the 

 "Marianna area" (by Jones, Rowe, Britton, Hardison and Zappone, 1910). 



This region embraces something Hke 450 square miles in Florida, 

 situated on both sides of the Chipola River in Jackson County, an:! 

 it extends a few miles into Alabama. Its nearest counterpart else- 

 where is in the red lands of Dougherty County, Georgia, and the 

 lime hills of southwestern Alabama, which are characterized by the 

 same or similar geological formations. 



Geology and Soils — The underlying rock is a Lower Oligocene 

 limestone which has been called Vicksburg in Mississippi, St. 

 Stephens or White Limestone in Alabama, and Marianna in Florida. 

 Ii is the oldest formation known to come to the surface in this state. 

 It crops out in many places, especially near the Chipola River,* and 

 is quite pure, an average sample analyzing 94 per cent of calcium 

 carbonate. Where exposed naturally on the uplands it is moderate- 

 ly hard, but a few feet below the surface it is soft enough to be cut 

 with a saw. This rock is used very largely in the red lands and 

 neighboring regions for chimneys and underpinning, and occasion- 

 ally for the walls of buildings. (It is probably safe to say that at 

 the present time the majority of the chimneys in Jackson County are 

 of this material ; and its use is equally common in the correspond- 

 ing parts of southwestern Alabama.) 



On many of the hills the Vicksburg or Marianna formation is 

 overlaid by a more clayey limestone belonging to the Chattahoochee 

 formation (L^pper Oligocene). The prevailing soil on the uplands 

 is a red loam, containing from about 15 per cent to 70 per cent of 

 silt and clay. Some of it is evidently derived from the weathering 

 of the Vicksburg and Chattahoochee limestones, while some may 

 represent newer superficial formations, such as the Lafayette. The 

 sandiest soils are usually on the highest elevations, remote from 



*In the soil survey of the "Marianna area" it was estimated that 

 there are 384 acres of rock outcrop in the area surveyed, which is mostly 

 west of the river; and there is probably enough rock east of the river to 

 bring the total up to a square mile, or approximately 1-5 of i per cent of 

 the whole area of the region. 



193 



