526 Transactions. 



north side of the large or, as I will refer to it later, Sunday crater ridge. 

 The bottom is a blue volcanic mud, and the water is clear, fresh, and good 

 drinking. 



South Bay Gorge bears witness to the vast amount of material removed 

 by subaerial denudation in Sunday Island. The ravines which intersect 

 the hills in all directions are deep, with steep, often precipitous, sides ; while 

 the tops of the ridges are narrow, usually 2 m. or 3 ra. wide, and some- 

 times, where not protected by vegetation, razorback edges. The boundary- 

 ridges of South Bay Gorge are pushed back by the action of rains con- 

 stantly removing the tuffs ; hence towards Denham Bay and Scenery Bay 

 they present convex outlines. The largest valleys on Sunday Island — 

 namely, those which descend to sea-level in South Bay and on the north 

 coast, where one has pushed its way right back to the Denham Bay ridge — 

 intersect the older tuffs of the Expedition volcano. Their basins are wide 

 at first, but narrow to gorges at the coast. Hence the depth and shape of 

 the valleys indicate their relative age. 



The greater part of the coast-line is formed of sea-cliffs. At their bases 

 are boulder beaches formed of fragments of lava set free by the disintegra- 

 tion of volcanic tuffs. There is a beach composed of coarse gravel in 

 Denham Bay, while at the base of the Terraces and on Low Flat are some 

 sandy beaches. 



Herald Islets. 



A group of seven rocky islets lying to the north-east of Sunday Island, 

 and known collectively as the Herald Islets, may be divided according to 

 their geological character into three sections — (1) Meyer Island, (2) Napier 

 and Nugent Islets, (3) Dayrell and the Chanter Islets. 



Meyer Island. 



Meyer Island is composed of lieds of a compact yellow andesitic tuff 

 (No. 5*), dipping to the north-west at an angle of about 40°. Lava dykes 

 traverse these beds in various directions, but the general trend is from 

 between north and north-west to between south and south-east. A large 

 dyke composed of dark-grey augite-andesite (No. 8) runs in a due north-and- 

 south direction in the northern islet. The soil on Meyer Island is the loose 

 weathered surface of yellowish andesitic tuffs (No. 10), which, from being 

 continually overturned by burrowing shearwaters {PufjS,niis assimilis and 

 P. chlororJiynchus), is constantly moving downhill. In a small gully on the 

 western slope is a bed of hard yellowish-grey fine-grained tuff (No. 18), 

 containing impressions of leaves, apparently belonging to the species 

 Nhopalostylis Baueri and Corynocarpus laevigata. A few plants of Coryno- 

 carpus are still to lie found on Meyer Island, and both species occur on 

 Sunday Island. 



Napier Islet. 



Napier Islet is composed almost entirely of beds of lava, enclosing here 

 and there blocks of coral, dipping to west-north-west at a high angle. 

 Fragments of coral, calcite inci'ustations, and water-worn stones were col- 

 lected on the summit ridge about GO ni. above sea-level. I am indebted 



* These numbers refer to the specitneiis described by Mr. Speight, wlut uses the 

 numbers origin<alIy given to them by me at the time of eolleeting (Speight, litJd). 



