CHAPTER 2 

 PHYSIOGRAPHY 



2.1 THE LOWER EVERGLADES 



Figure 5 presents a map of the 

 major physiographic delineations 

 within the lower Everglades drainage 

 basin. These delineations, as well 

 as those in subsequent sections for 

 Taylor Slough/Florida Bay and the 

 Florida Keys, are based upon pre- 

 viously published accounts (e.g., 

 Davis 1943, Puri and Vernon 1964, 

 White 1970, Craighead 1971), as well 

 as biological and hydrological fac- 

 tors such as dominant vegetation 

 types, hydroperiod, surface drain- 

 age, and circulation. The term 

 hydroperiod refers to that portion 

 of the year when the water table is 

 at or above the land surface. 



The lower Everglades subunit 

 can be further broken down into six 

 distinct physiographic areas: 



(1) Shark River Slough 



(2) Rocky Glades 



(3) Broad River/Lostmans River 

 Drainage 



(4) Coastal Swamps and Lagoons 



(5) Cape Sable 



Shark River Slough 



The Shark River Slough refers 

 to that portion of the Everglades 

 that is more or less synonymous with 

 Douglas' (1947) "river of grass". 

 Within the present study area the 

 slough is a broad southwesterly 

 trending arc of continuous wetland, 

 dotted throughout with numerous tree 

 islands. It is distinguished on its 

 northwestern and southeastern bound- 

 aries by expansive transitional 

 areas of slightly higher bedrock 

 elevation, and a consequently short- 

 er hydroperiod. The slough occupies 

 the center of the Everglades trough, 

 a wide, slightly concave depression 

 in the underlying limestone (White 

 1970). 



Rocky Glades 



To the south of Shark River 

 Slough lies a transitional area 

 known as the Rocky Glades or Rock- 

 lands (Davis 1943, DERM 1980). The 

 name "Rocky Glades" is derived from 

 the character of the limestone rock 

 that lies exposed at the surface of 

 this area. The limestone, which is 

 often called pinnacle rock, occurs 

 in craggy masses made of rock hard- 

 ened bryozoan colonies. These colo- 

 nies were laid down when the area 

 lay beneath sea level during the 

 late Pleistocene. 



The Rocky Glades form a thin 

 transitional area between the Shark 

 and Taylor Sloughs. Geologically, 

 the Fort Thompson Formation under- 

 lies the Everglades trough as a 

 surface bedrock feature, while the 

 back slope of the Atlantic Coastal 

 Ridge (Miami Limestone) forms the 

 surface rock for the areas farther 

 east. Consequently, these bedrock 

 features also make the Rocky Glades 

 a hydrologic transition zone between 

 the Shark River Slough drainage to 

 the southeast and the Taylor Slough 

 drainage to the south. 



Broad River/Lostmans River 

 Drainage 



To the northwest of Shark River 

 Slough the bedrock of the Everglades 

 trough again rises gradually in ele- 

 vation toward the Big Cypress Spur, 

 which is a southerly extension of 

 the Immokalee Rise, and the south- 

 western slope (Puri and Vernon 1964, 

 White 1970). These latter features 

 more or less define the Big Cypress 

 Basin. The freshwater wetland and 

 upland area between the Everglades 

 trough and the Big Cypress Basin is 

 labeled the Broad River/Lostmans 

 River Drainage. 



13 



