THE SEDIMENTARY FORMATIONS OF THE PANAMA CANAL 

 ZONE, WITH SPECIAL REFERENCE TO THE STRATI- 

 GRAPHIC RELATIONS OF THE FOSSILIFEROUS BEDS. 



By Donald Francis MacDonald, 



Formerly Geologist of the Canal Commission. 



INTRODUCTION. 



The following summary statement regarding the stratigraphic 

 geology of the Canal Zone is intended to make clear the stratigraphic 

 relations of the deposits from which the fossils described in the 

 accompanying memoirs were obtained. The descriptions of the 

 successive formations are taken from my paper entitled "Some 

 engineering problems of the Panama Canal in their relation to 

 geology and topography," 1 except that Dr. T. W. Vaughan has 

 changed the age classification of the formations as published in the 

 bulletin cited by referring the Bohio conglomerate to the Oligocene 

 and by placing the Gatun and Panama formations in the Miocene. 

 The small scale map (pi. 153), scale about 5 miles to 1 inch, is a 

 republication of the map contained in the same paper, of which it is 

 plate 4. It should be noted here that the Culebra formation out- 

 crops at locality station 6024, below the Emperador limestone, on 

 Rio Agua Salud; locality station 6025, Bohio Ridge; locality station 



6026, about 2 miles southwest of Monte Lirio; and locality station 



6027, in the old site of Bohio before the relocation of the Panama 

 Railroad. The position of each of these stations is shown on plate 

 154. The electrotypes for figures 26 and 27 were loaned by the 

 United States Bureau of Mines. 



The detailed descriptions of the local stations, which follow the 

 accounts of the geologic formations, except that of Bald Hill, near 

 Miraflores Locks, were made more or less jointly by Doctor Vaughan 

 and myself. The study of these exposures by both of us supplies to 

 Doctor Vaughan the basis for the accurate placing of the fossils 

 obtained in their stratigraphic relations. He prepared the key map 

 of localities here reproduced as plate 154. 



i U. S. Bureau of Mines Bull. 86, pp. 83, 29 pis., 9 figs., 1915. Particularly pp. 17-26. 



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