BY PROFESSOR STEPHENS, M.A., F.G.S., &C. 519 



Some of the subterranean streams which thus rise to the 

 surface under considerable hydrostatic pressure may originate in 

 the mountainous region to the S.E., and some portion may also 

 probably be derived from Lake Taupo and the Waikato drainage. 

 It is obvious that the springs must have their origin in the rainfall 

 of some district of larger area than that limited basin from which 

 the Kaituna and Tarawera flow. This is further divided into 

 two minor basins, Rotorua to the East, which is only a few miles 

 in diameter, and Tarawera^ which is four times as wide, and it is 

 encircled by a lofty barrier of rhyolitic lavas broken only to the 

 N.E. for the outlet of the river Tarawera, and presenting the 

 appearance of a vast general crater rim enclosing the separate 

 crater lakes of Rotokakahi, Rotornahana and Tarawera. 



It is worth notice that the water level of the first stands three 

 hundred feet higher than that of the others, indicating an 

 independent and probably later origin for this crater. 



We are then in possession of these facts or reasonable inferences, 

 — First, the area of the Lake district is as a whole about equal to 

 that of Lake Taupo ; secondly, both tracts are surrounded with a 

 rim of rhyolitic lava, the most recent of the local volcanic 

 products, forming in the one case an elevated barrier or mountain 

 ridge enclosing several lakes and mountains of volcanic origin, in 

 the other a sunken wall capped by pumice deposits. Now Lake 

 Taupo itself appears to have been formed by a long series of 

 explosions from more than one volcanic vent within its circum- 

 ference, rending away and dispersing their materials, and forming 

 or at least assisting to form the great pumice deposits of the 

 whole region to N.E. and S.W. 



And it is impossible to avoid the conjecture that all this region 

 the Lake District, is undergoing a similar series of processes to 

 that which has resulted in the formation of the older and single 

 la ke. By degrees, one would suppose, the greater portion of the 

 solid elevations over this area may be blown away or sink into 

 the cavities formed by successive explosions, until at last when the 

 violence of the subterranean heat has been exhausted, a tranquil 

 lake, like that of Taupo, may occupy the scene of the late and 

 present turmoil. 



