370 "ALBATROSS" TROPICAL PACIFIC EXPEDITION. 



terraces is well seen north of Point Hanourn, where a huge boulder- 

 like mass resting on the lower terrace is all that is left of the terrace 

 immediately above it. 



The harbor of San Luis d'Apra is protected on the north by Cabras 

 Island and the adjoining reef on the west, an outlier of the limestone 

 mass which has been broken through by the volcanic outburst (Pis. 195, 

 figs. 1, 2 ; 233, fig. 4). On the south of the harbor lies Orote Peninsula 

 (Pis. 195, fig. 3 ; 233, fig. 4), a broad low spit of elevated coralliferous lime- 

 stone ; the western face of its northern base is eaten away and forms the 

 shallow reef flat on the western face of the harbor (PI. 195, fig. 2). From 

 the anchorage in San Luis d'Apra we could distinctly trace the position and 

 extent of the i-emaining limestone masses (Pis. 195, fig. 2 ; 197, fig. 1). The 

 base of the long spit forming Orote Point (PI. 195, fig. 2) extends to the 

 eastern part of the harbor ; its structure is indicated by the characteristic 

 vegetation of a limestone area ; it is in marked contrast to the bare volcanic 

 slopes immediately in the rear. 



Cabras Island (PI. 195, fig. 1) consists of old elevated coralliferous 

 limestone, deeply pitted and honeycombed ; the limestone mass is full of 

 crevices, pot-holes, and funnels, covered with stalactites (PI. 196) ; numerous 

 fossils are found in it, mainly corals. Traces of a I'ecent elevation of from 

 three and one-half to four feet are seen in the undercutting of the small 

 buttresses of coralliferous limestone jutting out into the beach. This line 

 of elevation follows the shore of Cabras ; it is very recent, as is plainly 

 shown by the well-preserved calcified barnacles found on the under side 

 of the shelf where they had, been protected from the rain. Cabras Island 

 (PI. 197, fig. 1) does not rise more than eight to ten feet above high-water 

 mark; the shore is undercut and the island furrowed by numerous gullies; 

 it is full of caverns, crevices, and pits. 



In the distance, and running across the eastern flank of the harbor, rises 

 the highest point of the volcanic ma.ssif of the southern part of Guam 

 (Pis. 195, figs. 2, 3; 197, fig. 1; 198, fig. 2). To the north of Cabras 

 Island rise a number of elevated coralliferous islands ; they are outliers 

 of a point similar to Orote Peninsula, on a smaller scale, projecting from 

 the base of the western fiice of the volcanic mass of Guam (PI. 233, fig. 4). 



