Stream. These indications are in the form of trenches with a difference in level at the present day of the order of 6–20ft. No direct effect on vegetation is apparent unless perhaps on certain rock faces in the Makino tributary of the Mohaka. It should be put on record that no effects of the Hawke's Bay earthquake of 1931 (or, more particularly, of the after-shock that most affected Puketitiri) have been observed. (The main ridges and a route up the face of the range were traversed in 1930 and topographical photographs taken.) Minor earthquake shocks not noticed in the plains have occasionally been felt along the foot of the range. Drainage The Mohaka River, running south-eastwards, cuts across the grain of the country and forms the northern boundary of the range; it then turns northwards below the upper end of the Black Birch Range. The Ngaruroro and Taruarau running southwards in their upper courses form the western boundaries of the Kaweka Range and Hogget Block respectively. The Taruarau then turns east, cutting through the mountain axis between the Comet and the main Ruahine Range to form the southern boundary of the area under consideration. The Ngaruroro cuts through the mountain structure in alternate transverse and longitudinal valleys, first separating Te Pukuohikarua Ridge from the Manson Country, then running south between the latter and the southern Kaweka. It then turns east again to cut off Te Iringa from the rest of the range and, at Kuripapango, resumes a southerly course as far as its confluence with the Taruarau. Lithography Greywacke and Argillites Although massive greywacke shows in cliffs and pinnacles at all points on the range, much-contorted, closely banded mudstones are conspicuous on some of the eastern spurs and near the head of the Tutaekuri River. These mudstones are very friable, and in consequence the areas in which they occur show active erosion on a large scale. This affects the Makahu, Donald, and Tutaekuri drainage systems and especially Kiwi Creek, which runs from Studholme's Saddle into the Ngaruroro. Limestone There are two prominent limestone scarps on the east and two conspicuous uplifted blocks on the south of the Blowhard. There are also several smaller outcrops on approximately the same horizon on the Black Birch Range and south of Te Iringa. Pumice Pumice showers have blanketed the whole area to a depth of several feet. The Hawke's Bay soil survey lists these as immature pumice podzols formed from volcanic ash 3 feet deep in the Kaweka, Te Pohue, Titiokura, and Taupo series. Several showers are represented but cannot readily be distinguished under present conditions. The Taupo shower destroyed earlier vegetation west of the range crest, charred tree trunks and branches being plentiful up to 3 feet below the present surface. Above the bush line much of this pumice cover has been removed, and it has disappeared almost entirely from the crest of the range, but occasional hummocks occur there. Tongues of pumice held together by subalpine vegetation, mostly snow-grass, are characteristic of the slopes, even on steep gradients. These usually overhang at their lower margins and are being eaten away by frost action. Lumps of pumice up to 9 in long occur as far east as the crest, and a charred band is frequently present here, suggesting that a previous subalpine vegetation has been destroyed by