Art. LXII.—A Geological Reconnaissance of Northernmost New Zealand. By J. M. Bell and E. De C. Clarke. [Read before the Auckland Institute, 22nd November, 1909] Introductory— Page Introduction 613 Previous investigations 614 Physiography— The land— (1.) The tableland 615 (2.) The low hills bordering the eastern seaboard 615 (3.) The sand country 615 The coast-line 615 Drainage 616 Geology— Introduction 616 Mount Camel Series 616 Whangakea Series 617 Rahia Series 618 Coal Point Series— (1.) Lower beds 618 (2.) Upper beds 619 (3.) Petrology 619 (4.) Correlation and age 619 Older Débris 620 Newer Débris 621 Older igneous rocks— (1.) Igneous rocks associated with the Rahia Series 622 (2.) Igneous rocks associated with the Whangakea Series 622 (3.) Igneous rocks associated with the Mount Camel Series 622 (4.) Economic deposits in the older igneous rocks 624 Introductory. Introduction. The northern portion of the North Auckland Peninsula is an area of both geological and geographical interest. The sedimentary strata differ considerably in lithological character, and also apparently in age. The igneous rocks, while showing marked diversity in Texture, mineralogical character, and mode of origin, will probably be found to display a relatively close similarity in chemical composition. Several geographic cycles have passed over this sea-bordered area, each leaving its mark on the land. The area may, for the sake of convenience, be called the Aupouri Peninsula, after the Maori tribe that formerly occupied it in considerable numbers. A hurried reconnaissance of the Aupouri Peninsula made by us during the spring of 1908 had as its chief object the obtaining of a general conception of the main geological and geographical features for purposes of comparison with those of the Whangaroa Subdivision, further south, where detailed observations were at that time proceeding. The present paper is to be considered as a very imperfect summary of the geology of northern-most New Zealand.