338 Transactions. — Geology. 



mud or clay, because it always ran out of cracks and holes in 

 the ground at the time of an earthquake. 



About the centre of the property there are a number of 

 caves. The only known way of entering is to be lowered 

 down by a rope. When inside there is a slight glimmer of light 

 from somewhere ; but, as Paddy said when lost in a large 

 building, you cannot find the entrance out. I think these 

 caves were formed as follows : The entrance-hole is in the 

 centre of a slight hollow. Here, of com'se, the rain-water 

 would accumulate, and percolate through the sandstone to 

 the layer of mud, thence out at the bottom of the inland 

 cliffs to the swamp below, taking the mud and soft sand- 

 stone with it. Possibly when the swamps are fully drained 

 entrance to the caves may be found at the foot of the cliffs. 



I can see no difference in the stone axes and adzes found 

 at the exposed pa. However, I can onlj^ think that its origin 

 must date back to a time far beyond what we give for the 

 arrival of the Maoris — possibly to a previous race of people. 

 This \\e\\ is strengthened by the fact that in draining parts of 

 the large swamp to which I have referred my sons came upon 

 ancient di-aining-works, showing that these swamps had been 

 drained ages ago, at the cost of much labour and skill. Large 

 ditches have been dug, running from one mile to one and a 

 half miles long, and as straight as an arrow, from the river 

 back to the foot of the hills. 



Now, so far as my experience goes, the Maoris rather 

 prefer to make a swamp than drain one. They will build eel- 

 pas across streams, thus damming back the water, flood the 

 surrounding countrj', and so create a swamp. A large propor- 

 tion of the swamps at the Thames and the Waikato are said to 

 have been made by eel-pas, and there is evidence that some 

 of the Te Aoroa swamp has been thus made ; so I think the 

 old pa and the old drainage-works are the work of a race 

 which lived here before the Maoris. 



Art. XLII. — Notes on the Geology of Tongariro and the 



Taupo District. 



By Professor A. P. W. Thomas, M.A., F.L.S., F.G.S. 



[Read before the Auckland Institute, 30th July, 1888.] 



Plates XXVI.-XXXII. 



"We owe our first accurate knowledge of the geology of the Taupo 

 volcanic zone to von Hochstetter. Although he spent a com- 

 paratively short time in the district, his gi-eat geological insight 



