526 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 16, 



sandy mud, lying upon and covered by strata of irregularly worn 

 pebbles of trap. The shells themselves are very friable, powdering 

 away in the hand, but leaving a perfect cast in the matrix. While 

 the cliffs on the right hand rise to a height of 400 feet, nowhere 

 on the left do they exceed 100. These shelly deposits are now ten 

 miles inland, and are at an elevation of 300 feet above the sea-level. 

 The mode in which they have been deposited gives a striking example 

 of many changes in the nature of the sea-bottom succeeding each 

 other, at apparently regular intervals, for each bed has the same 

 average thickness. The shells have been deposited in a blue clay 

 exactly like what at the present day forms the bottom of nearly all 

 the harbours of New Zealand, while the alternating beds containing 

 no shells are made up of an arenaceous clay. 



Up towards the foot of Mount Grey, the bed of the stream gra- 

 dually becomes narrower, and is obstructed by great boulders of a 

 white sandstone, made up of fine particles of white quartz. Mount 

 Grey appears to be composed of an arenaceous rock, much altered 

 by heat) but the specimens obtained were not good, inasmuch as all 

 the rocks which appear at the surface in New Zealand have been 

 repeatedly under the action of fire (from bush fires) . 



The bed of the River Caratai leaves the S.W. flank of Mount 

 Grey, and we found the cliffs precipitous, averaging from 100 to 

 300 feet, and composed of imperfectly stratified layers of sand and 

 greenish mud. These beds have a dip to the N.W., and they overlie 

 a seam of lignite, 4 feet thick, dipping in the same direction. The 

 lignite resembles charred wood ; in many places it is so perfect, that 

 the bark remains entire ; while in others the central portion of the 

 stems has become infiltrated with sand and mud. Over these stra- 

 tified beds there is a layer of gravel, in some places 100 feet thick, 

 lying unconformably. This gravel forms the substratum throughout 

 the plain. The greater part of the plain must at no very ancient 

 date have been covered by dense forest ; isolated patches only, at 

 intervals of from four to eight miles, now remain ; successive fires 

 have gradually diminished their limits. Beds of semi-carbonized 

 wood are found in the alluvial deposit at the mouth of the Wai 

 Makredi, the principal stream north of Banks's Peninsula. 



Banks's Peninsula is a mass of lofty mountains, consisting of me- 

 tamorphic slates, traps, basalt, tuif, porphyry (claystone-porphyry 

 with felspar crystals), obsidian, scoriae, &c. The soil is a yellow 

 arenaceous clay, and in it are imbedded many specimens of the Moa. 

 There is abundant evidence to prove that at a very recent period the 

 peninsula was an island ; it is connected to the mainland by a very 

 narrow neck, and this neck is merely a succession of lagoons, very 

 slightly elevated above the sea-level. These lagoons are almost con- 

 tinuous with the great Waihora Lake, which extends round the 

 south-west of the peninsula. Inland, about two miles, there is a 

 chain of sand-hills, having all the appearance of once having formed 

 the sea-shore ; and this chain extends in a semicircle from the mouth 

 of the Wai Makredi to the Waihora Lake. These facts immediately 

 in connexion with the peninsula, combined with the shelly deposits 



