452 Transactions. — Geology. 



burrowed by worms at a time when the material was perhaps 

 covered with water. In several places the deposit has a kind 

 of scale or slickenside formed over its surface, and when sub- 

 jected to water-action for any length of time the clay has a 

 tendency to swell and break away suddenly from the sur- 

 rounding material. Over the Napier hills this brown mud- 

 clay is not associated with any shingle deposits, but this is not 

 the case in most of the other places where this clay is to be 

 found. In the clays exposed between Sturm's Gully and the 

 bluff overlooking the breakwater specimens of grit mixed with 

 loessic mud are to be met with, whilst in the surrounding dis- 

 trict extending from Tangoio to Puketapu the loessic clays 

 are associated with shingle deposits in such a way as to sug- 

 gest that the clays have been mainly derived from the shingle 

 by the percolation of water. I have purposely directed at- 

 tention to the smooth, worn, and rounded surfaces of the 

 limestones, and to the characteristics of the loessic clays 

 which either replace or overlie thern, as they form the text 

 upon which the following remarks are based. 



Those who are acquainted with the topography of Hawke's 

 Bay, or have read, with the aid of a reference-map, my de- 

 scription of the shingle deposits in this district, are aware how 

 widely distributed these deposits are. It is a curious circum- 

 stance that the shingle deposits, so far as my acquaintance 

 with the North Island is concerned, do not reach in a 

 northerly direction to the 38th parallel of south latitude, and 

 it is certain that the origin of the shingle must not be sought 

 for to the north of that parallel. Shingle deposits are found 

 in abundance farther to the south of that parallel, and they 

 appear to reach their greatest development in the South 

 Island eastward of the Southern Alps, the celebrated plain of 

 Canterbury being made up almost entirely of such deposits. 

 Years ago, when British and other geologists in the Northern 

 Hemisphere were striving to interpret the life-history of the 

 Pleistocene period by supposing the appearance of alternate cold 

 and warm climates within certain limits of the north temperate 

 zone, the ice or glacial theory took strong hold upon the lead- 

 ing geologists of New Zealand, and a number of papers 

 appeared in the Transactions affirming the once large exten- 

 sion of the glaciers in the South Island, and pointing out that 

 the Canterbury Plains are the outcome of a Glacial period, 

 the formation "in their upper portion being morainic and 

 in their middle and lower portion of fluviatile accumulations," 

 the material for the latter being brought from the area within 

 the glaciated districts. The late Sir Julius von Haast, in his 

 "Geology of Canterbury and Westland," estimates that 

 during the Glacial period the snow-line was 1,000ft. lower 

 than it is in New Zealand at the present time. This estimate 



