The Geology of the Lower Shag Valley, N.E. Otago. By O. D. Paterson, M.Sc., B.E., A.O.S.M.* On account of the author's departure from New Zealand, a condensation of his manuscript into publishable length has been made by Drs. W. N. Benson and F. J. Turner. [Read before the Otago Branch, November 7, 1939; received by the Editor, October 10, 1940; issued separately, June, 1941.] Introduction. The Lower Shag Valley comprises some fifty square miles of the Moeraki Survey District, North-east Otago (plate 7). The western portion consists of ancient metamorphic rocks (Maniototo Schists) overlain by residual patches of coal-measures which constitute the lowest unit of a series of Cretaceous to Miocene sediments covering the eastern portion of the area. In the north-east, however, in the Horse Range and near Shag Point, the basement-rock beneath the coal-measures is the only slightly-metamorphosed Kakanui Semi-schist. Physiographically also, the area consists of three units, the western, central, and north-eastern portions respectively. The first exhibits the now largely stripped and partially dissected peneplain cut in the schist; the broad, flat-topped interfluves bearing patches of the coal-measures are separated by steep-sided valleys. The central portion is the most extensive, and is characterised by the more subdued topography developed in the softer sandstones and mudstones, from which rise the highest points—Janet's Peak (522 ft.), Smyler's Peak (675 ft.), and Puketapu (1092 ft.) capped by igneous rocks. The Shag River follows a south-easterly or easterly course through this portion of the area, and is flanked by widely extending gravel-terraces. North-east of this the Horse Range rises abruptly to a height of about 700 ft., though further east it presents a gentler seaward slope. The coast is mainly bounded by cliffs over 80 ft. high bordered by low-tide beaches. The earliest geological work here was that of Mantell (1850), who distinguished between the concretions in the sediments at Katiki,† The spelling herein adopted is that which has hitherto been used by the Geological Survey, and, the writer has been informed, will be used by that body in future. It has been approved by the official Geographic Board (1934) for future use in maps to be issued by the Department of Lands and Survey in preference to “Kartigi,” which appears on most of the current maps issued by that Department and is used for the name of a railway station.—W. N. B. in the north-east of our area, and those at Moeraki, eight miles further north, and noted also the occurrence of coal at Shag Point. This coal was examined in more detail by Haast in 1871. Hutton (1875) assigned the Shag Point coal-measures to the Cretaceous, and the beds exposed around Palmerston to the Tertiary, believing that the two series were unconformable. Cox (1883) recognised the presence of a fault along the western margin of the Horse Range, and classified the unmetamorphosed sedimentary formations of the area into a single uninterrupted series of Cretaceo-Tertiary age. This view was supported by McKay (1884, 1887a), who included this area