146 Transactions. 



4. Young Formations. 



In two places on Sunday Island the original dry forest has been destroyed, 

 and young scrub or forest now occupies the ground. In Denhain, Bay a 

 large landslip occurred about four yeais previous to my ariival. The whole 

 face of the cliff up to 300 m. in height fell bodily forward on to the forest- 

 covered flat below, and buried under about 10 m. of earth and rocks an 

 area of 0-05 sq. km. About 1872 — the date is uncertain — Sunday Island 

 was in a state of eruption. From the Green Lake ashes, pumice, and 

 boiling water were ejected, and, falling upon the forest-covered crater-floor, 

 destroyed the vegetation. Beyond the crater it extended over Mount 

 Campbell on to Low Flat, and altogether covered an area of about 3 sq. km. 



The formations belonging to this section, here called " young " forma- 

 tions, are reversions (6 ; p. 26) to the first stages of the forest formations, 

 with this difference : that some introduced species of plants enter into 

 their composition, while introduced animals prevent the appearance of 

 certain species of indigenous plants. In the next section the dominant 

 species of plant in each formation is itself introduced. 



(a.) Landslip. — The surface of the Denham Bay landslip is extremely 

 rough, being for the most part composed of large and small blocks of lava 

 tuffs indiscriminately piled one above another. Among these are patches 

 of smaller stuff, gravel, &c., and it is in such places that plants obtain a 

 footing. Everywhere except in one place, where there is a small pool in 

 wet weather, water sinks in quickly. Logs aie lying here and there, while 

 round the edge is a belt of fallen dead trees. 



The landslip is sparsely covered with vegetation — some of it with rounded 

 shrubs, 4-6 m. tall, of Myofonini hetum and Coriaria sarmentosa. with a 

 few small trees of Homolanthus jjolyandrus and Boehmeria dealbata ; the re- 

 mainder quite bare, or with a covering of Ageratum conyzoides. Sccevola 

 gracilis, Mariscus ustvlatus, and small seedling Metrosideros villosa. Other 

 plants noticed on the landslip were Hahrrhagis erecta, Veronica breviracemosa, 

 Coprosma petiolata, and Poa polyphylla. 



(b.) Tutu (Coriaria) Scrub. — The soil in that portion of Sunday Island 

 affected by the eruption of 1872 is the surface of the newly deposited pumice 

 tuffs. It may consist purely of fragments of pumice, or a certain amount 

 of finer volcanic ash may be present. Near the Green Lake it is a bluish- 

 yellow clay, mostly covered with rounded pumice stones. Logs of trees are 

 lying about here and there, while some dead stumps are still standing. 



Tutu {Coriaria sarmentosa) scrub covers considerable areas in the crater, 

 occupying land of the very poorest and driest kind. It is a more or less 

 open formation, and consists principally of rounded Coriaria shrubs 3-5 m. 

 tall. Near the Green Lake shrubby Metrosideros villosa, 1-2 m. in height, 

 occurs. Flowering-plants ^ m. tall were observed on Naked Spur. 



The ground is quite bare in places ; elsewhere the vegetation is scanty. 

 Scirpus nodosus, Microtis unijolia, Sccevola gracilis, Gnaphalium luteo-album, 

 Ophioglossum coriaceum, and Imperata Cheesemani are perhaps the plants 

 most commonly met with, while near the Green Lake Lycopodium cernuum 

 and L. volubile are abundant. The last plant is much sought after by goats, 

 which eat it down close to the ground. 



In a small gully from which steam was escaping in several places were 

 found Dryopteris parasitica and D. setigera, whilst Nephrolepis exaltata 

 occurred on warm ground at the foot of some cliffs. 



