53 



Farther back from the rock which is being invaded is a broad 

 belt of tall scrub with the shrubs mentioned above, together with 

 various rain-forest species e.g., Asplenium bulbiferum, Polystichum 

 vestitum, Carpodetus serratus, Weinmannia racemosa, Melicytus rami- 

 florus, and other mesophytes. There is also a good deal of 

 Metrosideros lucida, so that the scrub will eventually become forest 

 of the same character as that forming the next belt of vegetation. 



A good many species usually confined to the subalpine belt descend 

 near the ice to within about 1,500 ft. altitude, or even much less.. 

 The following are examples : Agrostis Dyeri, Poa novae - zelandiae, 

 Geum parviftorum, Anisotome Haastii, Dracophyllum Kirkii, D. Traversii f 

 Veronica subalpina, V. linifolia, Coprosma serrulata, Celmisia coriacea,. 

 C. bellidioides, Olearia Colensoi, and Leucogenes grandiceps. 



L. COCKAYNE. 



THE GEOLOGY OF THE DUNEDIN DISTRICT. 



Our present detailed knowledge of the distribution of igneous 

 rocks in the Dunedin district is due almost entirely to the work of 

 Dr. Marshall and his students. Briefly, the region consists of a series 

 of Tertiary sediments resting on the planed surface of mica-schists. 

 On the eroded surface of these the volcanic complex was built up. 

 The mica-schists are probably the altered form of late Palaeozoic 

 or early Mesozoic sediments. The immediately overlying beds are 

 gritty sandstones with seams of exploitable lignite, which, traced 

 into regions immediately adjacent to the Dunedin district, are seen 

 to be covered by beds which in two or three localities have been 

 found to be fossiliferous. In one of these places is a limestone with 

 fragments of bivalve shells and belemnites which is probably of 

 late Cretaceous age, while in another, recently found by Fyfe, the 

 sandstone contains early Eocene molluscs. These are followed by 

 glauconitic mudstones, loose sands, marls with " Oligocene " (?) 

 Foraminifera, shark, fish, and penguin bones, a thin band of green- 

 sand, and a thick series of loosely cemented calcareous sandstones 

 with terebratulids, echincids, and a few molluscs, which pass up into 

 impure limestones with a more abundant molluscan fauna, shown 

 recently by Finlay to be of approximately " Miocene " age. 



The earlier portions of the volcanic rocks are exposed in the 

 southern, western, and eastern portion of the Dunedin igneous com- 

 plex. They consist chiefly of a series of dolerite and basalt flows, 

 with some trachyte in the east, and a minor amount of tinguaite and 

 trachydolerite. A succession of twenty-six such flows is exposed in 

 the Otago North Head. The later volcanic rocks forming the west, 

 north-west, and central portion of the region consist more largely of 

 trachydolerite and phonolite. Extensive explosions occurred near Port 

 Chalmers and Portobello, resulting in the formation of large necks 

 filled with breccia, from which radiate a series of tinguaite dykes. The 

 extent to which hypabyssal bodies such as laccolites or sills are asso- 

 ciated with the above-mentioned lavas is not yet quite clear. Between 

 successive flows there may have been very short intervals of time, so 

 that the upper flow may rest on the unweathered scoria of the first ; 



