542 BULLETIN 103, UNITED STATES NATIONAL MUSEUM. 



Section at Vamos a. Vamos, 2\ miles below Bohio, west side of Chagres River. 



Hill to the south across small ravine. 



Miocene (Gatun formation): Feet thick, 



2. Yellowish sandstone and small pebble conglomerate 50 



1. Dark bluish, fine-grained, argillaceous sandstone 



At and near landing, north side of the small ravine. 



60286-2. Yellowish sandstone, some fossils 75 



6028a-l. Dark-blue, argillaceous, fossiliferous sandstone, 



estimated 20 



Fossils: Cylichna, Turrilella, Cardium, etc. The exposure is rapidly- 

 becoming concealed by vegetation. Fossils were firmly embedded in 

 the matrix and not easily removed. 



Section on Panama Railroad from Monte Lirio to outcrop of Gatun formation on south 



side of Big Swamp. 



5. Hill of basalt; quarried for facing material for Gatun dam. 

 Miocene (Gatun formation) : Feet thick. 



6030-4. Bluish-gray, argillaceous beds which weather reddish; 

 locally contain pebbles, fragments of organic 

 matter, and many fossils. Pecten, dementia, 

 Encope megatrema, Callianassa vaughani. (This 

 bed is exposed on the north side of the swamp, 

 about 1£ miles north of Monte Lirio.) Dip about 



10° northward 100 



3. Fairly hard, sandy, drab-colored claystone; mas- 

 sively bedded and dips about 7° northward 50 



Oligocene (Bohio conglomerate) : 



2. Conglomerate, somewhat weathered and not extremely 



coarse; overlies sandstone, bedding not very clear. 

 Local unconformity. 

 1. Fairly coarse sandstone with a southward dip of about 20°. 



Section showing Gatun formation, one-quarter to one-half mile from Camp Cotton, toward 

 Monte Lirio, at big curve on railroad. 



Miocene (Gatun formation): Feet thick. 



7. Beddish soil '. . 10 



6029c-6. Bluish, fossiliferous argillite; contains some sandy 

 beds and some lenses of buff-weathering, consoli- 

 dated, impure fuller's earth 30 



5. Bluish argillite, which weathers buff 9 



4. Buff-weathering, consolidated, fuller's earth beds; 



not very pure 9 



6029d-3. Bluish argillite 10 



2. Buff-weathering, consolidated fuller's earth beds; 



not very pure 12 



6029a-l. Bluish, fossiliferous argillite; some sandy and pebbly 

 beds. Encope platytata, Callianassa vaughani, 

 exposed 20 



100 

 Dip of all above beds about 7° northward. Amphi- 

 steaina lessonii occurs in beds 6029a, b, and c. 



