GEOLOGY AND PALEONTOLOGY OF THE CANAL ZONE. 265 



5. There may have been minor oscillations, for instance the 5-foot 

 soborruco may represent slight elevation subsequent to the last 

 submergence. 



Mr. O. E. Meinzer, in his manuscript, "Geologic reconnaissance of 

 a region adjacent to Guantanamo, Cuba," referred to on page 204, 

 gives the following summary of events for the vicinity of Guantanamo : 



1. (Previous to the formation of the terraces) "Erosion, resulting 

 in the excavation of the principal valleys now in existence, some of 

 them probably below present sea level. 



2. Submergence sufficient in amount to bring the land at least 

 750 feet below the level of the present shore line. 



3. Successive stages of emergence and perhaps slight tilting of the 

 land, alternating with stages of quiescene, the emergence being about 

 850 feet in amount so that the land area stood about 100 fett higher 

 than at present, thereby permitting stream erosion below the present 

 sea level; during the stages of quiescence sea benches and cliffs 

 were formed at different, successive stands of the land. 



4. Submergence to the present level, resulting in the drowning of 

 the lower parts of the stream valleys and in the production of innum- 

 erable small estuaries, bays, and coves. 



5. Filling of the submerged valleys and development of a new sea 

 bench by destructive and constructive processes." 



The reefs considered in this section are fringing reefs. They rest 

 unconformably upon their basements, but were formed during 

 pauses in emergence. 



TERTIARY AND PLEISTOCENE REEF CORALS AND CORAL REEFS OF THE UNITED 



STATES. 



SOUTHEASTERN UNITED STATES. 



In the United States Tertiary reef corals first appear at the base 

 of the Eocene in the Midway group in Alabama, but these are not 

 sufficiently abundant to entitle the deposit to the designation 

 "coral reef." 



The oldest Tertiary coral reefs in this province are of middle 

 Oiigocene age, and have been studied at Salt Mountain, near Jackson, 

 Alabama, and near Bainbridge, Georgia. The basal contact of the 

 reef at Salt Mountain is not exposed, and its nature is, therefore, 

 unknown. The reef in the basal part of the Chattahoochee formation 

 at Bainbridge, Georgia, rests on the surface of the upper Eocene Ocala 

 limestone, which shows evidence of subaerial erosion, and is exposed 

 from place to place along Flint River throughout a distance of 8 

 or 9 miles. It is relatively thin, perhaps only 10 to 15 feet thick, 

 and contains a fauna of about 30 species of corals, mingled with 

 which are many specimens of Litliothamnion and large Lepidocyclina. 



The next younger development of reef corals is in the upper part 

 of the Chattahoochee formation and its stratigraphic equivalent, 



