324 Transactions. — Geology. 



Further to the eastward, and within 15 miles of Taupo Lake, 

 in the bottom of the Waipari Stream, these marl beds are also 

 exposed. They appear to dip to the westward at an angle of 

 10 degrees. They are here interbedded with coarse conglo- 

 merates, which enfold rounded slate pebbles and particles of 

 rhyolite and trachyte lavas. I saw no fossils here, but I did not 

 search much for them, and probably a closer examination would 

 disclose some. Where the deposit is crossed by the Taupo 

 track the height is 2,200 feet above the sea. These beds are 

 also exposed four miles higher on the same stream, at an eleva- 

 tion of 2,600 feet, and here they have interbedded with them 

 thin layers of yellowish clay or mud. 



In describing the third, or more recent, marl deposit in the 

 Taupo and Tuhua Districts, I do so with considerable diffidence, 

 lest my remarks may be misleading. 



On the higher elevations, on the ridges and mountain sides 

 west of Taupo Lake, and in the Tuhua District, appear in many 

 places what would seem to be the remains of a light deposit of 

 silt-like clay marl, the greater part of which appears to have 

 been carried away by atmospheric denudation. It consists of a 

 fine-grained clay marl, calcareous and sandy in some places, in 

 others more argillaceous in character. It has its greatest deve- 

 lopment in the little valleys on the top of the ranges. Lower 

 down, it appears only in places where it may have been carried 

 down by recent landslips. It is found overlying all the other 

 formations. Thus, at Matere, on the Hauhuugaroa Eange, it is 

 found at an elevation of 3,000 feet above the sea, lying on vol- 

 canic tuff and rhyolitic rock. On the Tangitu Range, west of 

 the Ongarue Eiver, it overlies the second marl, or blue papa 

 deposit. In some places the colour is a greyish-brown, in others 

 blueish, and again brown or brick-colour. On Matere Eange it 

 flanks the mountain side on the west, occupying the little valleys 

 between the edges in thin, fragmentary deposits. I have con- 

 stantly met with it in fragmentary slabs all over the Tuhua Dis- 

 trict, but nowhere else. It is thus only found to the west of 

 Taupo, and at a distance of about 40 miles from the centre of 

 the lake. I saw no fossils amongst it. A sample of the deposit 

 from llauhungaroa was found to be highly calcareous ; whilst 

 another, having the same appearance, and apparently the same 

 kind of deposit, found on Taurewa Mountain, 10 miles west of 

 Tongariro, proved to have no trace of lime in it. 



The source of this deposit is an interesting question. It 

 may possibly be laid down in the form of volcanic mud, con- 

 nected with the outburst of the Taupo volcanoes, when the great 

 masses of pumice which cover the surrounding country were 

 showered out ; or it may be a silt-like sediment of mud and clay 

 brought down from the higher elevations by running waters, and 

 deposited at the margin of the sea, at a time when the land 



