The Geology and Palaeontology of the Lower Waihao Basin, South Canterbury, New Zealand. By R. S. Allan, M.Sc., Otago University. [Read, before the Otago Institute, December 9th, 1924; received by Editor 30th December, 1925; issued separately 7th December, 1926.] Contents. 1. Introduction. 2. Work of previous investigators. 3. General Account of the Geology of the Area. 4. Structure. 5. Physiography. 6. Detailed Stratigraphy and Table of Classifications. (a) Pre-Notocene Coal Measures. Waimateian Stage. (b) Notocene Ototaran Stage. Hutchinsonian Stage. Awamoan Stage. (c) Notopleistocene. 7. Palaeontology. 8. Bibliography. Introduction. The area under consideration is part of the lower Waihao basin, in the county of Waimate in South Canterbury. A block of country 30 square miles in area has been mapped. The northern boundary runs east from Tussock Hill for 10 miles, while the western boundary follows a line drawn south through Tussock Hill for a distance of 3 miles. The eastern and southern boundaries complete the rectangular block. In the preparation of this paper the writer has to acknowledge his indebtedness to Mr. H. J. Finlay and Dr. J. Marwick for considerable help in the determination of the fossil mollusca; to Dr. J. A. Thomson for the determination of Brachiopoda; to the late Mr. R. Murdoch for the identification of land mollusca; and finally to Dr. W. N. Benson for his able teaching, friendly criticism, and helpful advice. Work of Previous Investigators. The first notice of the geology of the Waihao area is that of von Haast in his Geology of the Provinces of Canterbury and Westland, 1879. He recognised two formations, viz., a lower, Oamaru formation of Upper Eocene or Lower Miocene age; and an upper Pareora formation, of Upper Miocene or Lower Pliocene age. The Waipara series, of Cretaceo-tertiary age, Haast considered was not developed in the area. Von Haast seemed to favour the idea that the