HILL: GEOLOGY OF THE ISTHMUS OF PANAMA. 217 



projecting away from the point show the same topographic forms as the 

 mainland, and it is clear that they have been severed from it. 



From Mariato Point to Matapalo Head, the latter marking the ex- 

 tremity of the peninsula which encloses the Gulf of Dulce, the arrange- 

 ment and topography of the numerous islets present additional evidence 

 that in this region an immense stretch of the mainland has been eroded 

 by the Pacific ; the islands remaiu as monumental evidence of this decay, 

 being geologically aud topographically identical with the mainland. 



Our steamer strikes out due west from Mariato Point to Jicarita 

 Island, the southernmost of the Coiba group. 



A glance at Jicaron and Jicarita islands shows that they have clearly 

 once been connected with each other, and more remotely with the 

 mainland. They have the same identical coast characteristics as the 



Figure 17. Coast Topography between Mariato Point and Moro Puercos. 



islands of Panama Bay and Mariato Point, and likewise above this they 

 show the older peneplain topography. Jicaron is dominated by a three- 

 cusped mountain in its centre, identical in topographic aspect with many 

 of the summits of the Isthmian mainland. A small remnantal rock 

 stands a few feet from the main shore, rising to the height of the wave- 

 cut terraces, and apparently having been but recently separated by wave 

 action. Above the wave-cut coast bluff of the larger islands there is a 

 rapid slope of erosion ascending to the peneplain level. The rock of 

 these islands appears to be a white andesitic looking material. 



We get a distant view of the large island of Coiba sufficient to show 

 that it is of the same type of denuded mainland topography which we 

 have described. Here can clearly be seen the wave-cut cliffs, the Panama 

 peneplain and low summits similar to those of the Isthmian topography. 



From the passage between Jicarita and Jicaron the vessel strikes for 

 Cape Matapalo, and land is temporarily lost to view. The steamer did 

 not enter the Gulf of Dulce, but kept close to the shore line of the bor- 

 dering peninsula. The same wave-washed cliff lines are visible off Cape 

 Matapalo, the coast and the stretch of low peneplain extending inland 

 from it to the mountainous masses of the iuterior. 



