SANTA MARIA TO LOS ARROYOS 127 



though not an actual map of any particular 

 spot, shows in a simplified form the physical con- 

 ditions of the shore line and of the submerged 

 plateau, which are repeated continuously over a 

 hundred miles from Cape Gobernadora to the Bay 

 of Guadiana. West of this latter point (to Cape 

 San Antonio) conditions are materially different. 

 From the base of the pine-covered hills, usually 

 two or three miles inland, the coastal strip is 

 composed of soils brought down by innumerable 

 small rivers, the topography showing a gentle 

 gradient shorn of all conspicuous elevations. A 

 relatively slight sinking of the coast in very 

 recent time has flooded the shore strip giving 

 an indefinite shore-line of swampy character. At 

 intervals of two or three miles are islands of main- 

 land formation disposed at about right angles 

 to the general trend of the shore. These islands 

 represent the scant remains of low elevations 

 between the eroded river valleys now "awash " and 

 covered by a rather dense growth of mangrove. 

 Some of these islands have a core of solid land. 

 Tidal passages have been cut through some of 

 them, and their separation from the mainland is 

 not always positive. 



