330 Transactions. — Geology. 



under the name of lithaidit ; while Dr. J. Eatti has named a 

 similar lava upon the Liparian Islands, liparite. 



A specimen of the lava from Motutaiko, which I brought 

 down with me, exhibits the peculiar curved and ropy forms in 

 which it cooled, the thin lamellar sheets conforming regularly 

 to the curve of the stone. This island rock is possibly an old 

 volcanic mountain, the lower materials which formed the cone 

 being dispersed by the action of the water and the ordinary 

 subaerial denudation, and now covering the floor of the lake. A 

 distinctly marked terrace extends right round Taupo Lake, 100 

 feet higher than the present level of the water, indicating that 

 for a long period the lake stood 100 feet higher than it now 

 does ; the fall is probably due to the lowering of its only outlet, 

 the Waikato Kiver, where it probably broke through a barrier, 

 about one mile from the point where it leaves the lake. Te 

 Heuheu points out a flat rock, on the edge of the lake at Waihi, 

 which he says his ancestors used for a sacrificial altar shortly 

 after their first arrival in Taupo. This shows that the lake has 

 not altered its level within 400 years.' 



At Karaka Point, a promontory of the lake 4 miles from 

 Tapuaeharuru, are some interesting caves, worn by the action of 

 the water of the lake on the rhyolite tuff, at a time when the 

 water was considerably above its present level. There is also an 

 interesting natural archway, cut out of the tufaceous rock, and 

 instructive rounded, waterworn, and conical-shaped pillars of the 

 same formation. 



It has frequently been suggested that the only one outlet of 

 the lake — the Waikato River — does not seem to carry off as 

 much water as the numerous tributaries supply, and that con- 

 sequently there may be subterranean passages through which the 

 water flowed to supply the volcanic foci of the district. 



"Whilst surveying the lake I took the opportunity to measure 

 the volume of its rivers and streams. I append a table showing 

 the results of the measurements, which were very carefully taken. 

 They show that practically the same amount of water is dis- 

 charged as flows into the lake, the inflow being 16,483 gallons 

 per second, and outflow 16,230 gallons per second. 



As to the origin of the lake basin, I think tbere can be little 

 doubt, from the facts, that volcanic action has played a large 

 part in its formation. It is next to incredible that the waters of 

 the lake could have worked out such varieties of shape and con- 

 tour as are seen on the great coast-like cliffs of the western shores 

 of the lake. Their whole appearance bears evidence, I think, of 

 violent agencies, either of eruption or subsidence. The immense 

 pumice beds surrounding the lake, which gradually diminish in 

 bulk and size of the particles as they recede from it, are all cir- 

 cumstances which point towards the present site occupied by 

 Lake Taupo as being once the scene oi great volcanic activity. 



