544 BULLETIN 103, UNITED STATES NATIONAL MUSEUM. 



Exposures in the vicinity of Mindi Rill. 



Miocene (Gatun formation): Feet thiok. 



Gray-green, fine-grained, Bandy shell marl is exposed from 

 about 50 feet above sea level to 41 feet below; exposed thick- 

 ness about 90 feet. The material occurs in beds 2 to 6 feet 

 thick and is similar to that at the spillway. A number of 

 fossils were collected from the exposures near the bottom 



of the canal 6035 



Near the railroad is an extensive Pleistocene shell bed 

 from 6 to about 10 feet above sea level. Along the 

 canal the Gatun formation is overlain by lignitic or 

 peaty swamp deposits with occasional oysters. 



Monkey Hill, Mount Hope station. 



Miocene (Gatun formation): 



6036. About one-sixth of a mile south of the station on the 

 west side of the railroad is an exposure of dark-colored, 



fine-grained, sandy clay marl 20 



North of Mount Hope Station, along the east side of the railroad 

 on the north side of the cemetery, is the following exposure: 

 Miocene (Gatun formation): 



2. Clay, light-gray, stiff, slightly sandy, with white particles 

 of softer material, like the clay that overlies the marl 

 near Camp Cotton on the relocated Panama Railroad. 

 1. Dark-colored, fine, sandy, clay marl, the same as that ex- 

 posed at the locality immediately preceding. 

 Pleistocene reef-flat corals and other fossils occur 4 or 5 feet 

 above sea level in a swamp north and east of Mount Hope 

 and very near to the Colon road, 5850, 6038. 



Section of bluff at end of Tow Point. 



Pliocene (Toro limestone): 



Bedded coquina containing great numbers of barnacle plates, 

 comminuted shells, and a large Scala (Epitonium toroVnse 

 Dall), forms a bluff 45 to 50 feet high. It is dark to light- 

 gray in color, cross-bedded, and contains some lenses of 

 coarse, basic beach sand. The beds dip about 5° northward. 

 At the base of the bluff there is a fringe of coral-reef rock 

 which has been slightly elevated. This material has been 

 built around large masses of the Toro Point rock that have 

 fallen from the bluff, so that they are now inclosed in a 

 matrix of coral-reef rock which has been elevated perhaps 

 6 to 10 feet above the level at which it was originally formed. 

 This marginal coral flat is from 200 feet to a quarter of a 

 mile wide. Extensive fiat swamps filled with mud and 

 broken coral fragments fringe some of the higher land at 

 Toro Point. These are up to half a mile or more wide and 

 are about a foot, more or less, above high-tide level. 



The coquina rock forming the bluff at Toro Point seems to be 

 about the same as the coquina rock forming the top of the 

 hill at the west end of Gatun Dam, except that the latter is 

 light gray to creamy-white in color and is a purer limestone. 

 This formation clearly overlies the Gatun formation and is 



