HILL: GEOLOGY OF THE ISTHMUS OF PANAMA. 



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Lying to the northwest of Loreua Point is the island of Cano, which 

 rises from a submerged platform extending many miles westward out 

 into the Pacific. This island, as will be seen by the accompanying 

 sketch, consists of a remnant of the old coastal 

 peneplain. It, too, has many outlying remnantal 

 rocks. This island has undoubtedly been severed 

 by marine erosion from the Loreua mainland. 



From Cano Island no land is seen until we 

 reach Judas Point, marking the entrance to the 

 Gulf of Xicoya. The background consists of the 

 rugged mountains of the Sierra Candella. A high 

 summit, called an extinct volcano upon the hydro- 

 graphic chart, rises to a height of nearly 8,000 

 feet, while others near by in the background are 

 nearly 12,000 feet. These are apparently portions 

 of the great peaks which constitute the summit 

 region of the province of Talamanca, the south- 

 ward . continuation of the Costa Rican volcanic 

 plateau. Judas Point shows the same features 

 of outlying rocky islets, coastal swamp, wave-cut 

 cliffs, and the Panama peneplain, as we have 

 observed all the way from Panama to this point, 

 thus showing the continuity in this region of the 

 Pacific of the same geomorphic features. 



No student of topography can make this trip 

 along the Pacific coast from Panama to Punta 

 Arenas without being impressed by the fact that 

 large areas now covered by the waters of the 

 Pacific were once occupied by au extensive main- 

 land, which has been so destroyed by the erosion 

 of the Pacific that it is now represented only by 

 the few remaining islands and peninsulas we have 

 mentioned. A line connecting the outer point of 

 the peninsulas of Xicoya and Salsipuedes with 

 the outer capes of the Gulf of Panama will en- 

 close an area of the Pacific Ocean which has certainly been land at no 

 remote geologic period. 



The essential features of the Isthmian section can be traced along 

 the whole coast of the mainland: the continental mass of eroded 

 pointed mountains, bordered by the Panama peneplain, or erosion level, 



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