168 Papers from the Marine Biological Laboratory at Tortugas. 



In February, 1908, I went over the exposures along the Caloosa- 

 hatchee described by Dall in the preceding quotation, and observed the 

 phenomena. The Pleistocene deposits did not seem to participate in all 

 of the deformation of the Pliocene, pointing to the conclusion that defor- 

 mation intervened between the two deposition periods. This period of 

 elevation was succeeded by one of depression . 



EVENTS OF PLEISTOCENE TIME. 



The elevation described in the preceding section is supposed to initi- 

 ate the Pleistocene, but it is given an individual caption, following the 

 plan of separating intervals of uplift from those of depression. In a 

 region such as the Floridian, which lies outside the area of glaciation, 

 it is not possible sharply to differentiate between the end of the Pleisto- 

 cene, marked by the final retreat of the glaciers, and Recent, which 

 succeeded their disappearance. 



PLEISTOCENE SUBMERGENCE. 



The Pleistocene submergence was extensive. Along the western 

 extension and the west coast as far south as Tampa, a narrow border 

 was below sea-level. Proceeding eastward from Tampa Bay, marine 

 Pleistocene fossils are found at the following localities: Six Mile Creek, 

 at Orient Station, Hillsboro County; in a ditch alongside the railroad, 

 0.125 of a mile south of Manatee Station, Manatee County; North Creek 

 near Osprey; Caloosahatchee River; Kissimmee, in wells at depths of 

 90 to 100 feet; West Palm Beach, depth 74 feet; 2 miles southeast of 

 Eau Gallic; 4 miles west of Eau Gallic; 0.25 mile and i mile north of 

 Mims; Ormond, depth 50 to 56 feet; St. Augustine, at least 30 feet 

 thick, and on St. Mary's River near its mouth. 



The localities mentioned indicate that the Pleistocene shore-line lay 

 slightly north of the head of Hillsboro Bay, whence it probably passed 

 south of the southern end of the divide west of Peace Creek, keeping 

 between the 50- and 100-foot contours of the present land area; thence 

 it extended around the southern end of the divide between Peace Creek 

 and Kissimmee River, it followed the west side of the valley of the latter 

 stream, by Orlando, a few miles west of Sanford, and very likely the 

 area east of St. John's River was submerged; certainly the valley of this 

 stream and a coastal fringe from Daytona northward into Georgia were 

 under water. Over half of the present land surface of Florida was below 

 sea-level. 



The Pleistocene formations extend down the east coast and thence 

 across the southern end of the Peninsula, exhibiting relations to the old 

 Oligocene nucleus and the present coast line similar to those exhibited 

 by the Miocene and Pliocene, except there is a coastal fringe of Pleisto- 

 cene on the west coast north of Tampa Bay. 



DIFFERENCES IN PLEISTOCENE SEDIMENTS. 



The material of the marine Pleistocene varies greatly in different 

 areas. There are shell marls, coquina beds, the Palm Beach limestone, 

 the Miami oolite, the Key Largo and Lostman River limestones, and 



