ELISHA MITCHELL SCIENTIFIC SOCIETY. S^ 



occasionally chalcedonic, with weathered, imperfect forms of fossil 

 shells. Usually, however, there are no fossils to be seen. Occa- 

 sionally the rock is shaly, especially near the upper part of the bed. 

 It is overlaid by an irregular deposit of gray to blueish colored clay, 

 which near the shore has a thickness of one to six feet, or in wells 

 at some distance back, ten to twenty feet above tide. The land 

 near the shore has, then, an elevation of 12 to 14 feet above tide 

 water. Back from shore line, 50 to 200 yards, it rises to an eleva- 

 tion and twenty feet; and the surface, varying from level to undula- 

 ting, slopes from this point down toward old Tampa Bay. 



At a point on the shore above the one just described, and 1| 

 miles below Tampa, below and for three to four feet above tide 

 level are to be seen quite a number of rough, irregular masses of 

 marly limestone, occasionally quite marly, and imbedded irregular 

 masses of chalcedony. 



At Ballast Point, five miles south from Tampa, the underlying 

 limestone rock is cellular, soft and contains large quantities of eocene 

 shells. In thickness it extends from an unknown depth below the 

 water surface to three or four feet above. Here the point itself, 

 and a series of small points jutting out along the shore for a distance 

 of several hundred yards, are covered with numerous lumps and 

 irregular geodic, strangely shaped masses of chalcedonic fossiliza- 

 tions of limestone fragments, large coral stems and shells. 



Along Six Mile Creek, which runs into Hillsboro Bay at a point 

 east from Tampa, there are several good exposures of the eocene 

 rock. At Bunchville, where the railroad crosses the stream, six 

 miles east from Tampa, and for three-quarters of a mile downward, 

 the channel of the creek is narrow and tortuous, with steep rocky 

 banks. The water for one-quarter mile is shallow and the bottom 

 covered with blocks of limestone, while further down stream the 

 water becomes deeper and the channel gradually widens. The bot- 

 tom is hard, solid rock, (presumably the same eocene limestone) out 

 to the Bay. The cliffs are vertical, or nearly so, rugged, with lime- 

 stone rock extending up five to seven feet above water level, and 

 overlaid with three to five feet of sand, or sand with marl or clay. 

 The rock is full of imperfect shell prints at water level, and for a 

 few feet above. Nearer the upper surface it becomes a more soft, 

 lumpy white limestone, containing numerous shell prints. In places 

 in this limestone occur large blocks of chalcedonic quartz, of dark, 

 yellow and gray colors. The soft white limestone just below the 

 railroad bridge hardens on exposure, and would hence make a useful 

 building stone. 



