8 FERGUSON. 



diagonally across the island from Mabatuy Point on the west coast to 

 Desiay Point, the southeastern corner of the island. This ridge rises 

 abruptly from the sea at Mabatuy Point and extends southeast for about 

 2 kilometers where it reaches its highest elevation of about 460 meters at 

 the twin peaks of Mount Matareni, thence it runs nearly south for a little 

 over a kilometer, then turns southeast again, and where the Itlwd gorge 

 cuts through the ridge its direction is nearly east. (See Pis. II and III.) 

 Various spurs run off from the main ridge in all directions, and the 

 topography is extremely confusing. A prominent ridge, with minor sub- 

 sidiary ones, runs eastward from Chaua Point across the island. Another 

 ridge extends eastward from Mount Matarem, the latter forming, with 

 the main southeasterly ridge a large amphitlieatral valley drained by the 

 streams flowing through the Itbod gorges. The material of these ridges 

 is all volcanic agglomerate, with occasional outcrops of igneous rock and 

 scattered areas of stratified sandstone and conglomerate. The agglome- 

 rate ridges are sharp and ragged in their upper portions and are cut by 

 streams in deep box canons. The lower parts and the smaller spurs are 

 covered by a thick mantle of decomposed material, generally in the form 

 ■of a red clay with partly decomposed volcanic pebbles. The gradual 

 downward creeping of this material on the hillside has given a rough 

 stratification parallel to the contour of the hill. The agglomerate ridges 

 form steep cliffs when they reach the sea as they do at Chaua and Mabatuy 

 Points at the coast northwest from Itljod, and along the east coast of the 

 island south from Eskid Bay (north of Mananioy). Wliere they are 

 fissured, deep sea-caves are produced. 



South of San Jose de Ibana there is a series of terraces very similar 

 to those of Sabtan, but rather more regular, reaching a maximum eleva- 

 tion of about 275 meters and consisting of stratified volcanic material, 

 sand, gravel and pebbles. 



Northern Batan, north of a line drawn across the island from San 

 Carlos de Magatao, shows an entirely different style of top)ography, the 

 features of the landscape being controlled by the extinct volcano. Mount 

 Iraya. This mountain is a beautifully S}"mmetrical cone, its height as 

 given on the Coast Survey chart being 3,80G feet (1,160 meters). The 

 photograph (PL VI) shows that it was .once of greater height, an older 

 and larger cone having been blown away in a former eruption and a new 



