GEOLOGIC SECTION OF TERTIARY ROCKS. 77 



Miocene : Feet 



Chalky and coral limestones in beds of different thickness 450 



Gray stratified sand 8- 10 



Coral-bearing limestone ^ 100 



Sand and conglomerate 40 



Limestone 30 



Sandy stone 30 



White limestone 20 



Creamy white, very hard limestone with casts of lower Miocene 



shells abundant 110 



790 



Eocene : 



Rough, compact whitish limestone with vesicular surface and 

 the thick stratum penetrated by numerous caves 480 



Buff colored earthy limestone, weathering to rounded surfaces 

 and resting on a slight unconformity 100 



White soft limestone with some layers showing unequal harden- 



mg 180 



760 



Total thickness above the fault 1,700 



Beneath the fault, the equivalent vertical throw of which is between 

 250 and 400 feet, there is an extensive development of Eocene lime- 

 stones which may be roughly estimated in excess of the beds above 

 the fault at from 500 to 800 feet. The total thickness of Tertiary rocks 

 is therefore from 2,200 to 2,500 feet. 



There is a slight unconformity between the Miocene marl and sand 

 layers. 



At Pan de Matanzas, about eight miles west of the above section, the 

 thickness of limestone is about 1,000 feet, but denudation appears to have 

 removed most, if not all, of the Miocene strata. The Pan is on the side 

 of an anticline opposite to that where the section near Matanzas was ex- 

 amined. At the Pan the strata dip 10° north, 20° west. The features 

 of the post-Miocene erosion will be noted later. The Miocene strata are 

 moderately rich in fossils, both in the upper and lower parts of the for- 

 mation. In some of the beds, especially the higher, corals in small colo- 

 nies are common. The shells are most abundant in the lower beds. The 

 following species were collected and kindly determined by Dr W. H. Dall. 

 The corals were not determined. 



Cardium (near isocardia) densleonis (?), Pecten nodosus. 



Guppy. Gastrochsena sp. 



Siliquaria vitis {?), Conrad. ' Chama arcinella {?) , Lain. 



Balanophyllia sp. Area sp. 



Venus blandiana (?), Guppy. . Lucina sp. 



Ceritldum bitrnsii, Dall. Tsammohia^sp. not yet named (like Chipola). 



Turritella altilira, Conrad. Pectunculus {near pennaceus) , Lam. 



Turrltella sp. Thracia (belonging to subgenus CycUhodonta, 

 Conus (probably planiceps), Heilprin. Conrad), n. sp. 



