328 Transactions. — Geology. 



the question as applied to the King Country. The deep beds of 

 pumice in the valleys of the Whanganui, Pungapunga, and 

 elsewhere, are unquestionably alluvial deposits, the blocks of 

 pumice and loose sand being washed off the hill-sides, and 

 deposited partly, it may be, in the still waters of long narrow 

 lakes, which might be formed by the river beds being tempo- 

 rarily choked up by trunks of trees and detritus carried down in 

 heavy floods. 



The large area of country, and great height at which pumice 

 is found, precludes the idea that it is due to the action of water, 

 and all the evidence so far goes to show that it was spread in 

 the air, and, I think, points to the region of Lake Taupo as the 

 centre of distribution. It is true that many of the particles, 

 even amongst those found on the mountain tops, have an 

 abraded appearance ; but would not this be the natural result 

 of their mode of ejection from the crater, being carried by the 

 violent tornado of escaping gases high up into the air, and for 

 miles in any direction that the prevailing wind may take them, 

 their attrition in the air rounding off their angles ? 



Lake Taupo. 



In the month of January, 1886, 1 made a hasty hydrographic 

 survey of Taupo Lake, in connection with the topographical 

 survey of the country. I may here give briefly the results of 

 my observations, as they are intimately associated with some 

 interesting questions referred to, and may contribute to forming 

 a correct theory as to the origin of the basin. The lake covers 

 an area of 154,680 acres, being 24 miles 70 chains in length, 

 and 16h miles wide ; the mean depth is 65 fathoms or 890 feet ; 

 the greatest depth, at a point nearly in the middle, being 89 

 fathoms or 534 feet. Shallow water was found only at one 

 place in the lake, that is on the Haromatangi Reef, which lies 

 nearly half-way between Motntaiko Island and Karaka Point. 

 Here the rock is covered by only 7 feet of water. The 

 northern and western shores of the lake are formed of steep 

 rugged cliffs of rhyolites and augite-andesites, with great 

 compact masses of tuff. The height of the cliffs in the 

 western bay varies from 100 feet to 800 feet, with deep 

 water close alongside them, from 40 to 50 fathoms being found 

 with our boat made fast to the cliff. At Karangahape Point 

 the cliff is 1,500 feet in height, from its base at the bottom of 

 the lake to the trig, station on its summit. As will be seen 

 from the section, (Plate XIX.,) it rises perpendicularly from the 

 floor of the lake, almost overhanging the water ; thus, in taking 

 soundings, with our boat's stern touching the cliff, the lead-line 

 showed a depth of 390 feet, and a portion of the cliff 600 

 feet above our heads seemed to overhang the boat. Behind 

 these cliffs on the western side of the lake, and between the 



