338 Transactions. — Geology. 



in one place where a rugged footway has been formed by the 

 settlers. 



Lying immediately to the east of the crater I have described, 

 and separated from it by a narrow ridge, varying from about 800 

 to 1,500 feet in height, is the great crater of Sunday Island. 

 This has a length of If miles, with a breadth of 1J miles front 

 rim to rim, aud is, taken altogether, a very perfect specimen of 

 its kind. The internal slope of its sides is exceedingly steep, 

 indeed in many places it is quite inaccessible where not covered 

 with vegetation. The peak called Moumoukai, on its eastern 

 side, is 1,723 feet above sea-level ; and as the lake in the bottom 

 is but 40 feet above the sea, it will be seen that the crater is of 

 great depth. On the north side, however, the encircling rim is 

 much lower; one point, in a gap or break in the ridge, being only 

 180 feet above sea-level. At the present time the sides are generally 

 covered with vegetation, though here and there are bare places, 

 causedby the destruction of the trees during the eruption in 1872. 



The crater lake in the bottom is fresh water, and just one-third 

 of a mile in diameter, and nearly circular in shape. Captain Den- 

 ham's chart shows two little islets in it, but these are now sub- 

 merged, and only the dead tree-tops are to be seen appearing 

 above the water. The chart also shows a smaller lake, about a 

 quarter of a mile to the south of the other one, and this at that 

 time was surrounded by a ring of hills of no great elevation, 

 denoting a crater rim. It was in this little crater that the 

 eruption of 1872 took place, and which drove away the then 

 inhabitants of the island — a man named Covat, who, with his 

 family, escaped in a whaler to Fiji. When we come to consider 

 the size and depth of this great crater, it will be seen how much 

 material has been removed by that all-powerful agent steam. If 

 I am right in supposing the horizontal lava flows, seen in the 

 cliffs of the island, to be more ancient than either of the craters 

 to which reference has been made, it follows that these solid 

 beds have been removed altogether, and have been scattered in 

 fragments far and wide, whilst much of the pumiceous matter 

 ejected has also disappeared by the gradual washing away of the 

 shores of the island. In the fertile flats on the north coast of 

 the island, elevated 200 feefc above the sea, we find part of the 

 remains of this ejected matter, which must at one time have ex- 

 tended far beyond its present bounds. These flats are formed of 

 horizontal beds of pumice, andesitic and obsidian fragments, all 

 of which are easily acted on by the waves and the weather. No 

 lava streams can be traced as originating from the crater ; but 

 in more than one place on the north and east coast of the islands 

 there are dykes of very large size formed of andesite, and these 

 appear to have been forced through the pumiceous tuffs. They 

 are of somewhat different composition to the horizontal augite- 

 andesite lava flows described. 



