384 Transactions. — Geology. 



encouragement from this source, as the rapidly-altering cha- 

 racter of the Waitemata deposits would tend to show that 

 dynamic forces were at work during this period, causing fre- 

 quent oscillations of the land, thus preventing the accumula- 

 tion of sufficient vegetable matter at any period to form work- 

 able coal-seams. 



Workable seams of coal exist on the flanks of the Hunua 

 Eange, and dip in the direction of the Waitemata, but it is 

 doubtful if they reach as far as Auckland, and, if they do, 

 they would certainly be found at a great depth — probably not 

 much under 800ft. or 1,000ft., judging from the thickness of 

 strata which is known to exist between the Waitematas and 

 the coal at other places. 



Auckland stands in the centre of a great synclinal or 

 trough, and the depth to be penetrated there would be greater 

 than at any other point. Towards Howick on the one side 

 and Eiverhead on the other the depth of strata to be passed 

 through gradually decreases until, on the flanks of the Hunua 

 and Maraetai Eanges, the coal crops out on the surface. In 

 the case of the upper reaches of the Waitemata, wherever the 

 old floor or basement ro2k is found at or near the surface, and 

 whether it is composed of hydraulic limestone or slaty shales, 

 a careful search should be made for indications of coal, for it 

 was on such old floors that the coal vegetation grew and 

 flourished in the older Tertiary times. 



If, therefore, there is a probability of coal on the shores of 

 the Waitemata, it will be found in the upper reaches, in the 

 direction of Eiverhead, where the edges of the lower members 

 of Cretaceo-tertiary formation are upturned against the base- 

 ment rock. 



Art. XXXIII. — On the Occiirrcncc of Native Zinc at Hape 



Creek, Thames. 



By James Park, P.G.S., Lecturer, Thames School of Mines. 



[Read before the Atickland Institute, 24th August, 1891.] 



Last month Mr. George Manton, a settler on the right bank 

 of Hape Creek, discovered in his garden a heavy metalhc sub- 

 stance, which he handed to me for identification. This sub- 

 stance proved on examination to be metallic zinc, of great 

 purity, and coarsely crystalline structure. 



In reply to my inquiries Mr. Manton informed me that 

 when removing a quantity of gravel and boulders which he 

 had excavated from the well in his garden he was attracted 



