150 BULLETIN OF THE 



In dredging for a canal now under construction on the eastern coast of 

 Florida, in the waters of Mosquito Inlet, near the point known as Oak 

 Hill, the engineers encountered a ridge of commingled shell and coral, 

 through which they were compelled to go for a quarter of a mile or 

 more in a north and south direction. The top of this ridge was some- 

 what below the level of the waters of the lagoon, and presumably below 

 the level of low tide in the neighboring sea. Some specimens of the 

 dredging shown me by Dr. John Westcott, the President of the canal 

 company, contained fragments of Manacina apparently the same as the 

 living species. It thus appears certain that at least one species of the 

 living reef-making coral has in recent times dwelt along the shore to 

 the north of Cape Canaveral. 



The interior of the Floridian peninsula appears to be divisible into 

 three distinct districts. In the south, from the northern part of Lake 

 Okeechobee to Cape Sable, the surface is extremely level, formed proba- 

 bly in the main of organic waste accumulated behind the coral reefs, 

 upon which rests a thin and mterrupted coating of current borne sands 

 of inorganic origin. The only portion of this region which I have per- 

 sonally seen is the edge of the Everglades, about three miles west of 

 Cocoanut Grove. From the statements of Dr. Westcott and other ob- 

 servers as to the frequent occurrence of limy material in the Everglade 

 district, it seems to me most likely that the whole of this field above the 

 sea level is substantially composed of organic materials. The northern- 

 most part of the State, down into the base of the peninsula to a point 

 south of St. Augustine, probably consists of an older series of rocks, 

 mostly of Tertiary age, very uniformly covered by a deposit of detrital 

 sands brought to the region from tlie northward. Going southward 

 from the parallel of St. Augustine, we enter upon a region where the 

 surface is underlaid by the same sandy material as that found in the 

 northern part of the state, but the topography greatly changes its 

 character. In the northern section, the surface is in the main of the 

 gently undulating form belonging to the southern plain from Virginia 

 southwards. The deposits of sand are disposed so as to create gently 

 warped contours, the irregularities in height rarely exceeding ten or 

 fifteen feet within any one square mile. The form is that given by 

 slight marine currents where they act upon shifting sand. As we pro- 

 ceed southward, the irregularities of the surface become gradually more 

 and more accented, vuitil we gradually enter on a field known as the 

 Lake District, where the depressions without an outlet are so deep as 

 to enclose, not shallow morasses as they do in tiie more northern sec- 



