Northern Island is divided into two unequal portions by a watercourse 

 running roughly south-west to north-east, hereafter called Main Creek. To the 

 north of this are three bold granite summits. The highest lies above the head of 

 the creek, rising 781 feet, and called 781 Hill. This is connected with the two 

 other peaks, each about 600 feet high, by necks of high land. The eastern, East 

 Hill, rises above the mouth of Main Creek, with only a narrow col, that in 

 places is a bare granite ridge 3 or 4 yards across, connecting it with 781 Hill. 

 Between North and East Hills is a beautiful sheltered bay, the shore of which 

 is bare granite. North Hill and its neck rise precipitously from the shore of 

 this bay, but the slopes of East Hill and the col to 781 Hill rise more 

 gradually with an interesting talus slope that is traversed by a torrent bed ( North 

 Creek) draining from 781 Hill. Between 781 and East Hills is another water- 

 course draining the south side. This creek has a less precipitous bed; it "is a 

 tributary of Main Creek. 



Granite tors and boulders occur on most of the hilltops and exposed slopes 

 of these islands (pi. iv., fig. 2), but 781 and North Hills are remarkable for the 

 large slopes of bare granite that occur even upon their sheltered faces (pi. iv., 

 fig. 2, and pi. vi., fig. 2). These bare rocks are even expanses, in some cases 

 over an acre in extent. Some are precipitous, but many slope at only a low angle 

 and then end abruptly with a cliff 6 to 10 feet high. They are generally without 

 any vegetation except for algae that mark the watercourses across them. The 

 dark olive-green or black of these lines is in striking contrast to the grey-brown 

 of the granite rock. Such slopes serve as huge catchment areas from which 

 there is an immediate run ofif. The ground at their lower edge, however, has a 

 low water-holding capacity, and the drainage water falling on it serves rather 

 to leach soluble salts out of it than to increase its fertility. The soil immediately 

 below these slopes, then, is often coarser and more barren than is that further 

 away. 



The southern portion of the Northern Island has no striking physiographic 

 features. Its western end has bold granite tors ; towards the eastern end it 

 slopes gradually to the sea. Much of the area is a travertine limestone plateau. 



Middle Island (pi. viii., fig. 2) has a much smaller area, consisting of a 

 low summit, estimated at somewhat over 200 feet high on the west side, and 

 falling precipitously to the sea. The fall is more gradual on the east side with 

 talus slopes that spread as a fan upon a small travertine plateau. This latter 

 occupies about a quarter of the area of the island. At the south side of this 

 island is the small sandy beach that forms the only landing place on the group. 

 The sand is limited to a patch about 50 yards scjuare, though some — blown 

 from the beach — lodges in the cracks of the granite slopes lying immediately 

 behind. 



Southern Island has two peaks, one a mere collection of bare tors ; the other, 

 South Hill, near its south-east point, is 378 feet high. The two peaks are con- 

 nected by a ridge, the exposed southern face of which is a sheer precipice nearly 

 200 feet high. The coast, immediately below South Hill, is a sloping pavement 

 of granite swept bare by waves for over 100 feet. Southern Island also has its 

 travertine plateau, occupying almost a third of its area. 



Travertine Limestone. 



The travertine plateaux are a striking feature of the three islands. From 

 the sea they are at once recognizable by their more level appearance and the 

 dififerent colour of the vegetation they support. The travertine limestone lies 

 near the surface of the soil, but is usually exposed only at the cliff faces. The 

 overlying soil and underlying rock are obviously of granitic origin, more or less 

 cemented in the underlying portion by limestone. Shells of a land-dwelling 



