192 



THE GEOLOGIST, 



solfatara are often visited by the natives on account of the relief they ex- 

 perience in respect to their cutaneous diseases. 



A grand impression is made upon the traveller by those two magnificent 

 volcanic cones, Ruapahu, shining with the brilliancy of perpetual snow, Tonga- 

 riro, with its black cinder-cone capped with a rising cloud of white steam : the 

 two majestic mountains standing side by side upon a barren desert of pumice, 

 called by the natives One-tapu, and the whole reflected as by a mirror by the 

 waters of Lake Taupo. 



Lake Taupo is twenty-two English miles long in the direction from Terapa 

 to Tapuaeharuru, and sixteen broad. It is surrounded by elevated pumice- 

 stone plateaus, above two thousand feet above the sea, and seven hundred feet 

 above the lake. The Waikato river, taking its rise from Tongariro, flows 

 through the lake, traversing the pumice-stone plateau on either side. In 

 accordance with the names already proposed for the middle and lower Waikato 

 Plains, the Taupo country will form the Upper Waikato Basin. 



It is one of the most characteristic features in the structure of the Northern 

 Island, that from the shores of Taupo Lake an almost level pumice-stone plain, 

 called Kaingaroa Plain, stretches at the foot of the East Cape range, with a 

 very gradual descent to the coast between Whakatane and Matata. A plain 

 which, though now presenting a sterile appearance, will, I hope, at no distant 

 day, be converted into fine grassy land, capable of supporting large flocks of sheep. 



In a similar way, a higher volcanic plateau, consisting of trachytic tuff and 

 breccia, and various other volcanic rocks, stretches in a more northerly direction 

 to the east coast, between Maketu and Tauranga, the farthest extremities of 

 which reach even to the Auckland district. On one side of Hauraki Gulf, the 

 Coromandel range is covered with trachytic breccia, and again, on the west 

 coast, the same rocks form the coast-range from Manukau to Kaipara. This 

 extensive plateau is intersected by many deep valleys, the sides of which are 

 characterized by a succession of remarkable terraces. The same plateau is also 

 broken in many places by more or less regular trachytic cones, from one thou- 

 sand to three thousand feet high. If we take a wider view of the geological 

 features and the physical outline of these just described high plains and plateaus 

 consisting of regular layers of trachytic rocks, breccia, and tufP, we shall find 

 that the steep cones of Ruapaho and Tongariro rise from the centre of a vast 

 tuff-cone of extremely gradual inclination, the basis of which occupies the whole 

 country from shore to shore — from east to west — having a diameter of one 

 hundred sea-miles, and forming the largest cone of tuffs, or in other words the 

 largest crater of elevation in the whole world. 



Intimately connected with the described volcanic phenomena of the active 

 and extinct volcanic mountains are the solfataras, fumaroles, and hot springs. 

 They are found in a long series, stretching across the country in a north-north- 

 cast direction, from the active crater Ngauruhoe in the Tongariro system, to 

 the active crater of White Island (Whakari), occupying the chasms and fissures 

 already referred to. 



There is only one other place in the world in which such a number of hot- 

 springs are found that have periodical outbursts of boiling water, that is in 

 Iceland, the well known geysirs of which are of precisely similar character to 

 tlioso in New Zealand. Although there may be no single intermittent spring 

 in New Z(\'ilaud of equal magnitude with the great geysir in Iceland, yet in the 

 cxlenl ol" count ry in which these springs occur, in the immense number of 

 them, and in the beauty and extent of the siliceous incrustations and deposits. 

 New Zoahmd far exceeds Iceland. 



On the sonilun-n extremity of Taupo lake, at Tokanu, is Pirori, an inter- 

 mittent I'ouutaiii cif boilhig water, two feet in diameter, sometimes reaching a 

 height of lunre than forty feet. On the opposite side of Taupo, at the northern 



