Foerste — Eocene and Miocene- of Georgia and Florida. 47 



visited on a trip with Prof. Pumpelly and Mr. Alfred Brooks. 

 At the Natural Bridge, about 3 miles north of Marianna, the 

 Chipola Piver disappears under the ground, reappearing 

 farther on. At present a ditch or canal (6) diverts a part of 

 the water at this point, securing a partial surface flow. Dur- 

 ing the cutting of the ditch numerous echinoids and other 

 fossils characteristic of the Bainbridge marl bed, in a similar state 

 of preservation, and enclosed by a similar cement of Orbitoides 

 shells as at Bainbridge, were unearthed. East of this ditch, per- 

 haps a quarter of a mile distant, is a cave (5), the upper walls 

 of which are composed of a hard siliceous rock, containing 

 abundant Orbitoides. There is so much rock exposed at this 

 cave that it probably represents not only the siliceous layers 

 found above the marl at Bainbridge, but also the siliceous 

 bed c (localities 1 and 2), and the siliceous bed at locality 2^ 

 along the Flint Piver. At the edge of the river, where the 

 road running east from Marianna crosses the Chipola (2), there 

 is considerable siliceous rock which from its distance south of 

 the marl bed should be correlated with layer d, the .Russell 

 Springs layer of the Flint River section. Above this layer is 

 a whitish, porous, soft, pulverulent, silico-calcareous rock, 20 

 feet or more in thickness (1, near 2, 3, 4). This should corre- 

 spond to the rock once filling the interval between layers d 

 and e of the Flint Piver section though nothing similar has 

 been noted there. It is well exposed between Marianna and 

 the bridge crossing the Chipola (1, near 2), where a very thin 

 form of Orbitoides, and a Pecten are very common ; again, 

 about one and an eighth miles east of Marianna, in a quarry 

 south of the road (3) where in addition to a few of the fossils 

 just named, a small shark's tooth with very broad base, and 

 very short triangular tip was found ; finally about 2 miles from 

 Marianna, on either side of the road but especially in an old 

 quarry east of the road (4) where — in addition to the thin 

 Orbitoides and the Pecten — species of Lunulites, Cardium, Ce- 

 rithium, Turritella, and other fossils were found. The same 

 white pulverulent rock is found southeast of Marianna, along 

 the north side of the railroad, containing the thin Orbitoides, but 

 here a few siliceous beds are intercalated in the pulverulent rock 

 series. At first sight this rock presents lithologically an appear- 

 ance similar to many middle Chattahoochee exposures, such as 

 those along the railroad east of Chattahoochee, or the expo- 

 sures east of the landing of the same name, but the base of the 

 Chattahoochee no doubt does not crop out for several miles 

 down the Chipola Piver. 



