AGASSIZ: THE FLORIDA ELEVATED EEEF. 31 



Mr. Peter A. Williams, of Key West, was kind enough to have col- 

 lected for me samples from the Artesian well bored at Key West in 

 1895. This well was carried to a depth of 2,000 feet. Samples were 

 taken every twenty-five feet. The specimens I sent to Mr. E. 0. Hovey 

 for preliminary examination, and his report will follow this Bulletin. 

 The most interesting result obtained is that the thickness of the coral 

 reef formed since Pliocene times is probably about fifty feet. 



Dr. Hovey places the upper limit of the Vicksburg beds at 700 feet 

 from the surface, but he has been unable to determine the lower limits 

 of the Miocene and Pliocene. As will be seen by his report, many of 

 the samples indicate beach deposits, or deposits formed in comparatively 

 shallow water. The Foraminifera are now under examination, and it is 

 hoped that some light may be thrown on the subject from these results, 

 as well as from the comparative examination of the borings of other 

 Florida wells undertaken by the geologists of the United States Geo- 

 logical Survey. I have also added to Mr. Hovey's report the chem- 

 ical analysis of the samples kindly made for me by direction of the 

 Hon. C. D. Walcott, Director of the United States Geological Survey. 



On the smaller island to the southwest of Bahia Honda there is a 

 fine exposure of a portion of the elevated reef. The rock is full of heads 

 of Colpopbyllia, Mreandrina, and Orbicella. The highest point of the 

 elevated reef is not more than a couple of feet above high-water mark. 

 The lee side of the small island is in part covered with aeolian sand 

 derived from the breaking up of the weather side of the elevated reef 

 patch. In addition to the rcolian sand which covers the eastern part 

 of this small island we find sand composed of coralline and broken shells 

 and coral material, forming at some points a dike fully two feet high, 

 which has been thrown up by the sea. This small island is interesting 

 as showing how the underlying reef rock of the larger keys has gradu- 

 ally been covered over with seolian sand blown from the disintegrated 

 elevated reef itself, or how the sand has been piled up on the top of the 

 reef to leeward, and formed bars or flats which have gradually increased 

 until they have built up a great part of the land of some of the promi- 

 nent keys of the western extension of the Florida Keys. Or this sand 

 may have taken the place of the land eroded from the mainland by 

 the action of the sea after the elevation of the reef which edged the 

 former shore line of Southern Florida took place. 



The sand on Bahia Honda itself consists of the same material as that 

 described above, but it is more finely comminuted. At this point the 

 elevated reef must have been of considerable width, for its northern 



