372 "ALBATROSS" TROPICAL PACIFIC EXPEDITION. 



islands and islets south of Orote Peninsula, parallel to the west coast 

 (PI. 198, figs. 1, 2). This volcanic massif has burst through the mass of 

 coralliferous limestone which once covered the whole of Guam, so that its 

 southern part is really volcanic, with the exception of a few limestone 

 outliers (PI. 198, figs. 1, 2), while its northern extremity is composed of 

 elevated coralliferous limestone. 



Considerable denudation has taken place on the volcanic slopes of Guam, 

 as is shown on the west coast from the presence of huge isolated masses of 

 limestone and coralliferous rock elevated and left as outliers of the cliffs 

 once forming the second or third terraces. The extent of this denudation 

 is also seen in the interior of Guam, from the existence of the manifold 

 peaks, ridges, and pinnacles, forming a chain parallel to the outer line of 

 cliffs on the east side for about one third of the northern end of the 

 island. 



From our first position on the east coast, we could see the gradual change 

 taking place in the topography tov/ards the south, as the terraces of elevated 

 coralliferous limestone gradually died out towards the southern extremity 

 of Guam (PI. 233). On the western and southern sides of the mass of 

 volcanic rocks which has burst through the southern part of Guam the 

 former limestone masses which once covered the sides of the volcanic 

 outburst have in great measure disappeared (PI. 197, fig. 1), owing to the 

 extensive disintegration which has taken place over the whole southern 

 part of the island of Guam. The slopes of the volcanic hills consist of a 

 soft material, are much eroded, and are rapidly washing away ; the valleys 

 form diminutive canons with remarkably steep sides. 



To the south of San Luis d'Apra the slopes of the main ridge have been 

 greatly denuded and eroded. They are covered with patches of volcanic 

 red earth and with nodules of the same material. Towards the south the 

 shore reef has been elevated, although until we reach Facpi there has been 

 no volcanic outburst close to the coast. 



The peninsula of Orote is, like Cabras, composed of elevated coral- 

 liferous limestone. It contains well-preserved fossils ; they show no signs of 

 metamorphism, as do those collected in the vicinity of Mount Makana, east 

 of Agaiia. The fossils, however, are highly calcified, and their hardness and 



