124 Transactions. 



or tuff. Hence the variety of stations afforded for salt-loving plants is 

 limited. 



Through ther kindness of Captain Bollons I was able to land on all the 

 islands visited on the voyage from Sunday Island to New Zealand. I am 

 therefore able to give some account of the geology and botany of the three 

 islands of the Kermadec Group lying to the south-south-west of Sunday 

 Island. 



Macauley Island, distant 109 km. from Sunday, is 2 km. long and 

 3 sq. km. in extent. The highest point, 237 m. above sea-level, is near the 

 western end, and from here the land slopes away gradually to the east- 

 ward, terminating everywhere in cliffs which can be scaled at one place only 

 — the Lava Cascade. The island is composed of beds of pumice overlying 

 lava, and^ covered ^with some vesicular scoria and ash, which forms the 

 soil. 



Curtis Islands, 35 km. from Macauley, consist of two rocky islets — de- 

 tached portions of a crater in a state of thermal activity. The total area 

 is about 0-6 sq. km., and the highest point 100 m. above sea-level. The 

 crater-floor contains much hot mud and sulphur, while numerous holes 

 filled with boiling watei are dotted about. Apparently the islands are 

 composed of a kind of tuff. In the short time I was there I saw no lava. 



French Rock is distant 83 km. from Curtis Islands. It is composed 

 entirely of lava rocks, and is about 250 m. in length and 50 m. in height. 



The geological evidence of the age of the islands is conflicting. As 

 pointed out by Mr. Speight,* the occurrence of fragments of hornblende- 

 granite indicates the presence of a continental area. On the other hand, 

 any land connection with either Tonga or New Zealand must have been 

 very remote, as deep water now entirely surrounds the Kermadec Group. 

 The structure of Sunday Island is that of a tuff cone built up on a base 

 which at the time of the first deposits was submerged. The oldest visible 

 beds, which fortunately contain fossils, are of submarine origin, and do not, 

 I think, date back further than the Pliocene age. The character of the flora, 

 and the small proportion of endemic species of plants, are further evidence 

 of the recent appearance of the present islands above the surface of the sea. 

 That the Kermadec plateau once formed part of a continent extending in 

 a north-and-south direction is probable ; but the fragmentary nature of the 

 productions of the group demands that this land should be submerged before 

 the present islands came into existence (see 1 ; p. 161). 



IV. Climate. 



The Kermadec Islands are situated near the southern edge of a belt of 

 calms and variable winds lying between the south-east trades and the 

 region of westerly winds. This belt moves shghtly northward during the 

 southern winter, so that the weather experienced on Sunday Island in 1908 

 included many westerly gales during the winter months, but for the remainder 

 of the year w^as changeable, with some settled weather in March and April. 

 Generally speaking, the climate is mild and equable, with many rainy days, 

 considerable precipitation, much wind, especially in the winter months, 

 and a constantly humid atmosphere. 



* " Petrological Notes on Rocks from the Kermadec Islands, and some Geological 

 Evidence of a Former Subtropical Pacific Continent." (See p. 241 of this volume.) 



