Vol. 54.] MR. J. S. aARDINER ON THE GEOLOGr OP KOTUMA. 9 



pit is not situated at the top of a steep conical rise, but almost on 

 the flat. Its pit, too, is much broader at the top and not nearly so 

 deep. It has one long tunnel, out of which two caves run. The 

 first rises at once to some extent and then has a sudden drop of 16 

 feet into a tunnel which proceeds almost at right angles to it, and 

 down which a lava-flow has coursed, of the same character as in the 

 tunnels of Sol Mafiri. The second has its lava-flow into the main 

 tuunel. 



The lava-beds in the neighbourhood of these two pits show many 

 small caves or overhanging ledges, caused apparently by the lava 

 underneath flowing away after the crust above has cooled. In one 

 place just under Matiri is a circular pit about 3 feet across. It is 

 about 10 feet deep, and shows the flow of lava for 20 to 30 yards. 



The tunnels seem to be comparable to that left by the lava-stream 

 above Hilo, in the eruption of Mount Kea, Sandwich Islands, of 

 1880-81,^ but the stalactites would seem to be absolutely dissimilar, 

 and stalagmites are practically absent in the Eotuman tunnels. 



lY. Western Islands. 



Ilea, to the north, is formed of essentially the same volcanic ash as 

 the hill of Sororoa opposite to it. It is about 900 feet high, and is 

 thus about 40 feet higher than any hill on the main island. On every 

 side it is bounded by cliffs, which to the north and west are very high 

 and precipitous. To the north-west near the summit they are over 

 800 feet. While round Sororoa there is even on the most precipitous 

 face a small fringing-reef, none is present around Uea. Eastward 

 the island slopes more gradually, but a landing, on account of 

 the steepness and breakers, has nearly always to be effected by 

 swimming. The strata in the cliffs round the island are generally 

 horizontal, but at the landing-place have a tendency to dip or 

 be curved slightly and show much false bedding. In the ash- 

 rock embedded volcanic fragments occur, but rarely, and never in 

 large blocks. In places under the action of fresh water, near certain 

 streams, the rock becomes more like shale. JS'ear these, too, a red 

 earth is found, which lathers slightly, and is used as a soap. 



Halfway between Uea and Hatana is a small reef, Hofhaveanlolo, 

 about 60 yards across, partially uncovered at low tide. Hatana 

 really consists of two islands inside the same fringing-reef, with 

 cliffs to the west. 



Hoflewa, 2 miles south-west, is a crescent-shaped island open to 

 the north-east, with cliffs all round. The whole island is, like Hatana, 

 a mass of dense, hard, black, very slightly vesicular lava. 



V. Meteorological Conditions. 



Except during December, January, Eebruary, and March, the 

 prevailing winds are E. to S. ; in the above months they vary from 

 JS". to W. Very heavy rainstorms often come up with the E. 



^ J. D. Dana, ' Characteristics of Volcanoes,' 1890, p. 209. 



