530 Transactions. 



The cliffs in Scenery Bay present a series of lava-flows horizontal in 

 section, and cut by several dykes. Between the lower flows at D'Arcy 

 Point are portions of beds of yellow andesitic tufE (No. 13) of submarine 

 origin. A lava-flow at sea-level in Scenery Bay is composed of dark-grey 

 andesitic basalt (No. 41). A specimen of andesitic basalt (No. 40) from the 

 same locality was taken from a dyke 2 m. to 3 m. wide, and running north- 

 west and south-east. 



Titi Knob, which is the name given to a small hill above Boat CWe, 

 is composed of a mass of lava and tuff which shows httle orderly arrange- 

 ment, and is in places thoroughly mixed with coral. A typical specimen 

 of the lava is composed of andesite containing many fragments of coral 

 (No. 22). In one spot on Titi Knob is a rock showing planes of stratification 

 and containing fossils (No. 25). It consists of a coarse gravel composed of 

 grains 1 mm. to 3 mm. long cemented by white calcite. Included are frag- 

 ments of lava up to 2 cm. long, coral, and molluscan shells. I could not 

 trace this for more than 2 m. or 3 m. in any direction. The fossils collected 

 included fragments of the following molluscan shells : Trochus. Nassa, 

 Area decussata Sow. C?), Chione. 



The north side of the Sunday crater ridge consists of pumice tuffs con- 

 taining numerous fragments of lava rocks and hornblende-granite. Here 

 in several places angular fragments of the granite may be seen projecting 

 from the cliff -face, and those which were extracted were easily crumbled 

 to their coarse constituent grains, whilst on the shore occur numerous 

 water-worn boulders of various sizes up to about 50 cm. long. The pumice 

 tuffs rest on hard andesitic tuffs, apparently belonging to the newer sub- 

 marine series. 



Within the crater on the western side of Blue Lake is a large flow of 

 olivine-andesite (No. 34), dipping gently in a northerly direction, and which 

 may be traced until its upper surface reaches the level of the lake and dis- 

 appears under the pumice tuffs of the north side of the crater-ridge. Above 

 this lava-stream to the summit of Mount Campbell. 285 m. above sea-level, 

 there is nothing but pumice tuffs. 



At the base of Moumoukai, on the eastern side of Blue Lake, a good 

 section is exposed. The lower beds, about 40 m. in thickness, are evenly 

 statified horizontal yellow andesitic tuffs (No. 14) of submarine origin and 

 similar to those at D'Arcy Point, but differing in their composition to the 

 larger series of newer submarine beds which enter so largely into the for- 

 mation of the lower portion of Sunday Island. Above the submarine beds 

 of Moumoukai is a stream of andesite (No. 9) identical in external appear- 

 ance with the olivine-andesite on the opposite side of Blue Lake, and ap- 

 parently only another part of the same flow. Above this are several other 

 lava-flows, while the upper half of Moumoukai, in common with the whole 

 upper part of the large Sunday crater rim, is composed entirely of pumice tuffs. 

 The inner crater surrounding Green Lake also consists of pumice tuffs. 

 On the southern shore of the lake was found a fine-grained tuff (No. 32) 

 containing rounded bombs. 



From the foregoing description it will be gathered that Sunday Island 

 is a tuff cone, with here and there near sea-level a few lava-flows and dykes. 

 In three places only — Moumoukai, within the crater; Big Hill, in Den- 

 ham Bay ; and Scenery Bay — arc there exposed to view cross-sections of a 

 number of lava-streams. The floor of the crater is near sea-level, and 

 cliffs exposing sections are the rule both within and without the crater, 

 yet nowhere was hornblende-granite f(.nnd in situ. 



