Boult. — Occurrence of Gold at Harbour Cone. 429 



occurs in considerable abundance. This fossil lias been identi- 

 fied by the Geological Survey and Hutton, but in a recent paper 

 by Professor Park and Captain Hutton the identification is 

 disputed, the name Pseudamusium huttoni being assigned to 

 the fossil. 



The remainder of the Peninsula is covered by a thick cover- 

 ing of volcanic rocks, forming lofty mountains and ranges. 

 With the exception of basalt they are almost all very alkaline 

 in character. Dr. Marshall in his section on geology in " Dun- 

 ediu and its Neighbourhood " shows a map in which areas are 

 covered by basalt, dolerite, trachyte, trachytoid phonolite, 

 nepheline basanite, nepheline tinguaite, and kenyte, similar 

 to that described by Gregory from Mount Kenya in East Africa. 

 It is upon the very highly denuded surface of the Tertiary 

 sandstones that these rocks outpoured, a fact shown bylthe 

 variation in the level of the outcrops of the sandstones 



Harbour Cone. 



A glance at the map accompanying will show that this peak 

 and its immediate neighbourhood is on the surface almost en- 

 tirely composed of bostonite. The surface of the land is pre- 

 cipitous, and rises to Harbour Cone to form in appearance almost 

 a typical denuded volcano and its bared solid pipe. The bos- 

 tonite has a very great extent in this neighbourhood. It forms 

 cliffs along the shore of the harbour to the east of Port Chalmers, 

 and also tops the small hills surrounding the central peak. 

 The central portion of the peak itself is composed of solid basalt 

 extending down to the 900 ft. contour-line. Below this down 

 to 750 ft. boulders of basalt cover the ground thickly, having 

 been wedged off by frost and other natural agencies and rolled 

 into their present position. On the northern slopes of the 

 mountain an irregular area is occupied by a coarse breccia, 

 very indurated, containing fragments of trachytoid phonolite 

 and other rocks in large and small angular fragments. This 

 is the Port Chalmers breccia, the greatest occurrence of which 

 is on the peninsula on which Port Chalmers is built, which con- 

 sists almost entirely of the breccia. The breccia also forms 

 the upper portions of the small hill to the north-east of the 

 main peak, as indicated on the map. The most important 

 inclusion in the rock is large and small masses of alkaline 

 syenite, showing that this rock must have enormous extent 

 under the surface at an unknown depth, as the focus of the 

 explosive eruption producing the breccia is somewhere near 

 Port Chalmers. 



The flanks of the mountain are pierced by numerous dykes. 

 The position and nature of those occurring in the neighbour- 



