This paper dealt with two theories of the origin of the old lake basins of Central Otago—that of Dr. Hector, which accounts for these basins by the unequal movements of the land—and that of Professor Hutton, who advocates their having been excavated by ice.
The author agreed in the main with Dr. Hector's theory, but differed in the details as to how it was brought about, and with respect to the age of some of the beds found in these old lake basins. The author's theory is, that in Miocene times a large river flowing across North Otago was checked by the upheaval of the coast line, and converted into a series of swampy lakes, the eastern outlet of which was barred by volcanic rock, thus gradually deepening the lakes, and determining for a time the outflow of their waters by way of the Molyneux River. Subsequently, movements determined the area of the Taieri watershed, and compelled its waters to escape by their present channel along Strath Taieri.
Mr. Cox disagreed with Mr. McKay on his theory of formation of the lakes. He thought that to a large extent they had been excavated by the action of ice, and we had evidence of the great glaciers which had existed during Cretaceous times. He instanced the Blue Spur and Weatherstone's Gully as illustrations of this, and argued that these glaciers, which had deposited the drifts, had also in the first instance determined the configuration of the land, and that in all subsequent elevations and depressions, the form of the mountains then assumed, had been more or less maintained.