GUAM. 375 



highest point of Mount Makana, about 600 feet above the town. Some 

 of the terraces are clearly indicated on the island of Cabras as well 

 as at the extremity of Point Orote (Pis. 195, fig. 3 ; 196), and on the 

 western face of the peninsula, where they gradually disappear^ owing to 

 denudation. 



Mount Makana is about 600 feet in height; its summit' consists of 

 various kinds of volcanic rocks ; it has protruded through the coral- 

 liferous limestones, a spur of which extends to fully 400 feet along the 

 side of the mountain towards Agaiia. 

 Near the sea coast, and to within a 

 few hundi-ed yards of the point of 

 protrusion of the volcanic material, 

 the elevated coralliferous limestone 

 is of moderate hardness, containing 

 many well-preserved fossils. Near 



the point of i unction between the ^^'^'ction <,f Vm-CANic Outburst and Lime- 



^ •' _ STONE, West Coast of Guam. 



volcanic mass and coralliferous lime- 

 stone, however, it suddenly becomes highly crystallized, very hard, and the 

 fossils disappear. The coralliferous strata are much tilted at this point, 

 plainly showing that the volcanic mass has burst through the coralliferous 

 limestone. From the anchorage we could trace this bed of limestone broken 

 into cliffs and lifted into masses with precipitous sides by the volcanic 

 outburst, the limestone belt being clearly indicated by its characteristic 

 vegetation. 



Volcanic agencies have been at work at Guam in very recent times. 

 Unata was destroyed by an earthquake in 1849 ; this is not remarkable, as 

 Guam is at the extremity of a long line of active volcanoes extending south 

 from Japan ; it may be that the volcanic outbursts which have pushed 

 through the limestones, or have elevated parts of the islands of the 

 Ladrones, are of comparatively recent date.^ 



We can imagine a large island like Guam, partly composed of coral- 

 liferous limestones, to be gradually eroded to the level of the sea, by a 



1 The marine barracks and other buildings at Agana -were destroyed by earthquakes on the 26th of 

 September last. 



