propylites to the sedimentary rocks is not very clear, but the former are supposed to underlie the latter, having probably the character of an intrusive volcanic outburst.
All around the centre of trachytic rocks, from Taiaroa Head, Cape Saunders, Tomahawk Bay, to Forbury Head, through Lookout Point above the Caversham tunnel to Flagstaff by Abbot's Hill, near Green Island, and past Swampy Hill to Blueskin Bay and Purehurihu, is an including belt of basalts. In other places there are only outlying patches, as at Saddle Hill, Stoney Hill, East Taieri, and North Taieri. The southern limit of the trachyte appears to be at Anderson's Bay on the east, and Pine Hill on the west. As has been stated, small coal seams are interstratified among the tufaceous volcanic rocks, but these have not, so far, been proved to be of a profitable character, nor is it likely that they will be. Attention has been drawn to the resemblance between this district and the Thames goldfields, where valuable mineral veins intersect the dioritic rocks, and the propylites of Portobello resemble those of the northern locality, but are much more crystalline, and at the Thames there is not such a strong development of the surrounding basalts. As we shall subsequently see, the parallel is not only in lithological and geological conditions, for at Harbour Cone, in the crystalline diorite rock, there has been found sufficient gold, if not to create a prosperous goldfield, at least to cause a hope that such a desirable consummation may some day be attained.
In places the basalts exhibit very beautiful columnar structure, notably at Forbury Head, Green Island Bluff, on Mts. Cargill and Mihiwaka, and on Stoney Hill near Brighton. In many instances incipient columnar structure is developed, and spheroidal concretions are very distinct in the rocks upon which the First Church is built. In some localities the bold cliffs formed by these hard rocks give rise to very fine scenery, the Forbury Head, upon which stands Mr. Cargill's mansion, and more notably on the Peninsula, a little to the eastward of Lawyer's Head, where there are vertical cliffs 800 feet in height.
At the Glen quarry and in the Woodhaugh Valley beautiful zeolitic minerals are found, with crystals of calcite and aragonite, and good specimens of hyalite may be obtained at the former of these localities, as also at the Forbury cliffs. In the Kaikorai
