GEOLOGY AND PALEONTOLOGY OF THE CANAL ZONE. 541 



Oligocene — Continued . 



Culebra formation — Continued. Feet thick. 



eri, some echinoid fragments, also Conus, 

 Natica, Turritella, Pecten, Amusium, Lucina, 

 etc. This is probably the equivalent of the 

 upper limy beds of the Culebra formation. 



Exposed 25 



6026a. Two miles south of Monte Lirio : Somewhat coarse- 

 grained sandstone which contains a few pebbles; 

 massive, and weathers into large spherical 

 masses; fossiliferous, Stylophora and other corals, 

 Lithothamnium vaughani, Lepidocyclina canellei, 

 Nummulites panamensis? , Conus, Pecten, Ostrea, 



etc. Seems to be nearly the same bed as 36 



Bohio conglomerate — 



2. e-f. Rather massive, soft, buff-weathing sandstone. 

 No fossils noted. Slight dip southward. Ex- 

 posed 20 



Unconformity. 

 2. a-d. Railroad cuts which show exposures of conglomer- 

 ate and sandy beds, dip about 7° northward. 

 Unconformity. 

 Eocene? (Las Cascadas agglomerate): 



1. Dark, basic, andesitic agglomerate and breccia, showing 

 some local overlaps; roughly bedded; dips 10° northward. 

 (Fault zone here several feet wide trends N. 30° W. and 

 dips 83° southward. Downthrow side on the south. 

 Much sheared lignitic shale has been dragged into the 

 fault zone. Some silicified wood found in the shale.) 



Exposure a quarter of a mile northwest of old Bohio railroad station. 



Oligocene (Culebra formation) : 



6027. Orbitoidal marl is exposed in the flat, the bottom of the 

 canal, at the base of a hill that has been cut away. 

 This is Hill's locality for "Orbitoides forbesii," which 

 is Lepidocyclina canellei. 



Exposure opposite old Bohio railroad station, north side of the railroad track. 



Oligocene (Bohio conglomerate (?)): 



A cliff about 75 feet high composed of dark-colored agglom- 

 erate of pyroclastic origin. This agglomerate is overlain at 

 the second telegraph pole north of the 15th milepost from 

 Colon by a small pebble conglomerate in a matrix of coarse, 

 gritty sand. 



Section at Pena Blanca, about 1 mile beloiv Bohio, on the west side of Chagres River. 



Oligocene (Bohio conglomerate)): 



The entire hill is composed of dark-colored conglomerate of 

 hornblende andesite porphyry pebbles, cobbles, and 

 boulders embedded in coarse sand. No exposure of the 

 orbitoidal marl was observed. Dip toward the northeast, 

 50 feet thick. 



