Page:Transactions and Proceedings of the New Zealand Institute - Volume 1 (2nd ed.).djvu/35



is proposed to confine the remarks in this paper, firstly, to those boulders which are of considerable size; or secondly, those which appear to belong to rocks not found in situ in this part of the country.

Under the former bead we find in numerous localities—as, for instance, on Belmont Hill, on the Porirua Road between the Tutaemanu Peninsula and Duck Creek, at Makara, &c.—large blocks of dioritic sandstone apparently deposited in lines, and generally resting upon decomposing sandstones.

Several theories may be propounded as to the mode of deposition of the blocks.

Firstly, they may be the hard nuclei of strata the softer parts of which have decomposed.

Secondly, they may show the lines of old watercourses before denudation bad worn down the valleys to their present depth.

Thirdly, they may be ice-carried. Although the dioritic blocks are of the nature and character of rocks in situ in the neighbourhood, yet rocks of the same character abound on the opposite side of the Strait, as also generally throughout the Tararua range; so that there is no primâ facie reason why these boulders may not have travelled from a distance, as well as those of the second class, which we propose afterwards to consider.

The second class of boulders consists of rocks not found in this vicinity and which must have been brought from a distance. Of these not many have yet been discovered. I have myself found the following:—

1. A block of granite about a foot long, found between Evans and Lyall Bays, several hundred feet from and about twelve feet above high