a—9

54

Table Mountain grey moderately-fine-grained breccias again are seen, but these may represent some of the bands seen farther to the west, the slope of the range being at a greater angle than the dip of the rocks. Finally, within the watershed of the Waiwawa and Waiwawa Creek, falling into the Kauaeranga, the Thames-Tokatea rocks are overlain by rocks belonging to the Beeson's Island group, and the further continuation of the section to the north-east does not again show the presence of the Thames-Tokatea rocks. In the section taken from the shore of the Frith of Thames across the Thames Goldfield, east-north-east into the Kauaeranga Valley, and thence along the valley of Hihi Stream, a tributary of the Kauaeranga, and across the main range to Broken Hills, whence the line continued reaches to the sea at Ohui (Motuhana). In this section the rocks of the Thames-Tokatea group are little more than three miles across. This is due to the gradual approach westward of the Beeson's Island Group, which has a very large development in the Kauaeranga Valley. For this part a nearly parallel section is described by Mr. Park, illustrating his report on the Thames Goldfield, published in the Mines Reports for 1894, from which extracts descriptive of the geology of the district were made at page 36 of this report. Mr. Park shows the belts of hard and soft or " kindly " country, but not the sequence of these as higher or lower beds ; and, in view of two lines of fault crossing the section-line, no doubt there is difficulty in doing so. The different belts of country with the numerous reefs in this field, according to some authors, dip and hade towards the westward, and this would be a reversal of the general inclination of the group farther to the north. This, however, can only apply to the country as far as the Look-out Rocks ; and, while admitting that the dip is in parts and may generally be to the westward, the theory of the general succession of the different groups of the volcanic series is not thereby affected. About two miles before reaching the Kauaeranga River the Thames-Tokatea rocks give place to those of the Beeson's Island group, and are not again met with on this line of section. Puriri Area. —The Thames-Coromandel area of the Thames-Tokatea group of volcanic rocks is terminated on the north side of the Kauaeranga River, to the south of which the Beeson's Island group and strata of pleistocene and recent date form the mountains west of the main waterparting and the downs and lower grounds to the westward. South of the Kerikeri Valley rocks belonging to this group begin on the lower spurs of the mountainous district, at first with a limited breadth of exposure in an east-and-west direction, but in the Puriri Valley this increases to at least two miles, and in the southern branch this breadth is exceeded, owing to the valley being scooped out in superincumbent rocks at higher levels, but cut into the lower group in the deeper parts of the valley. To the south, towards Omaha Valley, the breadth over which these rocks are found lessens rapidly, and they are not seen on the south side of .that valley. Their most interesting development is between the two branches of the Puriri River and along a line of characteristic hills flanking the higher range between the south branch and Omaha Peak, on the north side of the valley of that name. On the north side of the Puriri Valley the country formed of these rocks presents hills of rounded outline, with here and there a craggy protuberance standing above the general level. Between the two branches of the Puriri a mountain of pyramidal form rises from the level of the plain, and to the eastward is connected as an offshoot of the main range by a ridge dividing the headwaters of the north and south branches. The belt of Thames-Tokatea country on the south side of the watershed forms a series, in line, of conical hills quite distinct from the lower hills and rolling downs that interpose between and blend with the eastern margin of the plain, and are equally distinct from ranges formed of rhyolite that rising to greater heights lie to the eastward. The section along the Puriri Valley shows the position of these rocks in relation to those of the Beeson's Island group that occupy the hills of smoother outline and low grounds to the west, and the rhyolite rocks that form the mountains to the eastward. Along this line to the westward no junction between the Thames-Tokatea rocks and the younger group can be made out, but from the point where the south branch leaves the hills and enters on the alluvial plain, upwards, the valley and adjacent hills show the presence of greenish or grey sandstones and breccias formed of volcanic matter that closely resembles the class of country which, at the Thames, is regarded as the most favourable for the occurrence of gold. Higher up the valley and higher in the sequence of the rocks, towards the east and passing under the Rhyolite formation the rocks are lava floes or consolidated tufas of a crystalline texture and dark colour, as fine-grained or coarser andesites. In this direction the Thames-Tokatea rocks are followed by a coarse volcanic breccia that indicates the presence of the Beeson's Island group interposed between them and the rhyolites. Gold-mining has been carried on in the Puriri Valley since shortly after the opening of the Thames Goldfields, and prospecting is still being carried on on two or three lines of reef, some claims on which appear to have good prospects. Southwards, towards Omaha, prospecting is also being carried on, but in this direction none of the works were visited. Karangahake Area. —This begins on the north side of the Ohinemuri Gorge, half a mile to the north of where the old road to the Upper Ohinemuri and Waihi crosses the saddle to descend again to the level of the river ; and from Mackaytown through the Ohinemuri Gorge the Thames-Tokatea rocks are well displayed to the point where the deeper part of the gorge ceases, a little before reaching the point where the old road joins the new. The western boundary crosses the spur outrunning from Karangahake Mountain, and to the southward runs along the lower slope of the range to where the coach-road begins to ascend the outstanding range projected north-west into the plain, this being formed of Beeson's Island rocks, as shown on the geological map accompanying. The same rocks have extension south-east on to and across the range between Karangahake and Te Aroha Mountains into, across, and beyond the Waitawheta watershed, and thus separate the Karangahake from the Te Aroha area of the Thames-Tokatea group.