CussEN. — On the Piako and Waikato Biver-basins. 399 



the present water-level, and the other 330ft., clearly showing 

 that formerly the lake was at a higher level. The Waikato 

 leaves Lake Taupo at Tapuaeharuru, and flows in a north-east 

 direction down a well-defined valley for nearly twenty miles. 



An inspection of the map will show that the Waikato 

 basin here is bounded to the westward by a mountain-chain 

 whose highest peaks are 3,800ft. above the sea. They run 

 nearly parallel with the western shores of Lake Taupo. There 

 is a general persistent trend in the range in a direction 

 N. 40° E. Lateral offshoots diverge, but the general axis of the 

 main chain has a dominant direction nearly north-east. This 

 chain is continued on to Whakamaru and Tikorangi, and 

 becomes confluent with the Patetere plateau and the high 

 wooded country to the westward of Eotorua, where it dis- 

 appears or becomes coalescent with the disjointed hills, Ngo- 

 ngotaha, Okohiriki, &c., which lie directly to the west of Eoho- 

 rua, and stand from 2,500ft. to 2,600ft. above the sea. Twenty 

 miles to the east of this main range lies the valley through 

 which the Waikato Eiver flows from Taupo Lake to Waiotapu 

 Valley. The Waiotapu was evidently a continuation of the 

 valley above through which the Waikato Eiver flows from 

 Taupo. The two together form the oldest topographical 

 feature of the country, and along their course on either side 

 are to be seen evidences of immense denudation as they were 

 widened and deepened. To the west of them, extending to 

 the main range, the ground is left projecting into high ridges 

 and prominent isolated hills with valleys filled with alluvium, 

 this general trend being from the range into the Waikato and 

 Waiotapu Valleys. I think it is more than probable that 

 the Waikato at one time flowed through the Waiotapu Valley 

 to the sea on the East Coast, and that the main range before 

 referred to formed the watershed of its basin on the north- 

 west side. But its channel was obstructed, probably by sub- 

 terranean disturbance or the volcanic action in the Eotorua 

 district ; it quitted the original valley, and eroded for itself a 

 new channel in nearly a due west direction, through a pass of 

 the range between Whakamaru and Titiraupenge. 



The topography of the country and the land-sculpture in 

 the new river-valley bear out this view. The waters of the 

 river were poured back into the valleys, which they occupied 

 for a time in the form of a serpentine lake or lake-like river 

 with many arms spreading in between the spurs of the ranges. 

 Eound Tuahu, Ngautuku, and the other hills between Atea- 

 muri and Taupo, are seen the old lake-beds filled with allu- 

 vial deposits. In the valleys between the hills are immense 

 beds of pumice and sand in horizontal layers, sometimes over 

 200ft. in depth. Through these the streams have worn their 

 channels down to the bed-rock, disclosing stratified layers of 



