.4 Contribution to the Geologic History of the Floridian Plateau. 147 



Toward the east the Apalachicola Group is overlain near the eastern 

 boundaries of Baker and Bradford counties by Miocene sediments (Jack- 

 sonville formation). The Miocene projects southward, as a tongue, over 

 the Apalachicola as far as Waldo. Northwest from Palatka to the south 

 fork of Black Creek the Apalachicola boundary is formed by the Pleisto- 

 cene of St. John's River valley. Along the west side of St. John's River 

 valley, from Palatka southward to Enterprise Junction, the boundary 

 is formed by the overlapping of the Pliocene Nashua marl. The boundary 

 curves to the southwest of the latter town, passes through Orlando, Lake- 

 land, and reaches the Gulf at Tampa. Along this stretch from Enter- 

 prise Junction to Tampa, the boundary is between the Apalachicola and 

 the Pleistocene. South of Tampa two small outlying areas of Apalachi- 

 cola sediments are known, one at Ellenton near the mouth of Manatee 

 River; the other at White Beach, 1 between Osprey and Sarasota. 



MIOCENE. 

 Two Miocene areas are known in the State, a western and an eastern. 

 The former extends westward from near Tallahassee, and is bounded 

 on the north by deposits of the Apalachicola Group, and on the south by 

 those of Pleistocene age. The eastern area has its western boundary 

 formed by the Apalachicola Group. Except below the south loop of 

 St. Mary's River, where the Apalachicola outcrops, the northern boundary 

 is formed by Pleistocene deposits to St. John's River, about 6 miles north 

 of Jacksonville. From Jacksonville to St. Augustine on the east the 

 Miocene passes below Pleistocene and also from St. Augustine westward 

 to the South Fork of Black Creek. This area of Miocene is bounded on 

 the west by rocks of the Apalachicola Group; on the north, east, and 

 south by Pleistocene. 



PLIOCENE. 



There are two principal areas of Marine Pliocene. The more eastern 

 and northern of them (the Nashua marl) flanks the Apalachicola Group 

 from Palatka to Enterprise Junction along the west side of St. John's 

 River, and is overlain on the east by Pleistocene formations. On the 

 northeast the boundary runs southeast from Palatka toward Daytona, 

 thence it turns south to Osteen, then westward to Enterprise Junction. 



The other area of Pliocene (the Caloosahatchee marl) is mostly 

 overlain by Pleistocene deposits, and outcrops of it are seen only along 

 streams, the Miakki River, Chiloccohatchee River, Peace, Prairie, and 

 Alligator creeks, all of which flow into Charlotte Harbor and Caloosa- 

 hatchee River. 



PLEISTOCENE. 



Southeast of the surface exposures of the Nashua marl and coast- 

 ward of the southeastern and southern margin of the Apalachicola Group 

 lying west of those exposures the entire surface to the sea front is 

 formed by Pleistocene formations, except a few outliers of the Apalach- 

 icola Group, the marine Pliocene Caloosahatchee marls along some 

 streams, and the non-marine Pliocene Bone Valley gravel near Bartow, 

 from Homeland to Mulberry, and at Bone Valley. 



1 It seems that this locality was not included by Messrs. Matson and Clapp 

 in their report. 



