DETAILED DESCRIPTIONS OF ROCKS. 47 



and pink compact rhyolite without porphyritic felspar, but containing 

 numerous minute grains of quartz. The flows have an undulating 

 westerly dip of about io°. 



The greater portion of the groups of hills at Agolai, eight miles south- 

 west of Baorli, is composed of a strongly porphyritic rhyolite, dark grey 

 or reddish brown in colour, with rather fresh looking crystals of felspar 

 and numerous grains of quartz, in fact the most common type of Mal- 

 ani lava. Some" of the flows exhibit a fairly well marked columnar 

 structure, especially at the base of the pea"k (912 ft.) close to the 

 village of Dugar. Flow-structure is not uncommon, and is especially 

 well developed in a small hill at the south-west end of the group, the 

 upper part of which consists of a rock strongly resembling pitchstone. 

 This flow is inclined to the south-east at about 32 . The usual dip 

 of the beds in this group of hills is to the north or north-east, at 

 angles varying from horizontality up to 45 . At the south-eastern edge 

 of the group is a bed of vesicular lava also exhibiting flow-structure, 

 associated with some greenish ash beds dipping N. E. at io°. Another 

 variety of rhyolite is seen in the low hills near Agolai on the western 

 edge of the group; this is a compact greyish red rock, with very few 

 porphyritic crystals. Near the top of the peak close to Bugar, on the 

 north side, a patch of breccia is intercalated with the rhyolites, consisting 

 of angular fragments of rhyolite imbedded in a dark coloured matrix. 

 Some other brecciated beds are seen on the slopes along the southern 

 edge of the group, but these appear to be flows of rhyolite broken 

 up in situ, probably by movements in the mass when partly solidified, 

 and re-cemented ; the fragments only show on the weathered surface 

 of the rock and are not visible in section. 



Between Agolai and Korna, six miles to the south-west, there are 

 several low rises consisting of the reddish brown porphyritic rhyolite 

 and covered with angular gravel derived from the disintegration of the 

 rock in situ. At Korna there are three or four small hills, the upper por- 

 tion of which consists of thick flows of rhyolite dipping at a low angle 



( 47 ) 



