Thomas. — Geology of Tongariro and Taupo. 347 



of Euapehu at one end, then the two crater-lakes of Nga 

 Puna-a-tama, the lofty active cone of Ngauruhoe, and then 

 the direct line is continued by the South and North Craters on 

 Tongariro. 



If, with a slight deviation in direction, the line be con- 

 tinued to "White Island, we find that it passes through a large 

 number of points remarkable for their volcanic activity, in- 

 cluding Tarawera and Eotomahana. This line may therefore 

 be justly looked upon as the main line of volcanic activity in 

 the Taupo volcanic zone. 



Nor is this the only instance of great fissures connected 

 with the volcanic activity of the district. In the northern 

 part of the Taupo zone we have two lines marked by hot 

 springs as w^ell as by dislocation of the rocks. These lines are 

 parallel to the main line, and probably correspond to great 

 fissures in the rocks. The first of these lines, seven miles 

 from the main line, stretches from Orakeikorako along the 

 east face of the Paeroa Eange to Eotoehu, a distance of thirty- 

 seven miles. The second line is eight miles further to the 

 west, and stretches from the hot springs on the Waipapa 

 Creek, near the Waikato, through Eotorua to Eotoiti. 



"We may reasonably ask whether these lines of fissm-e are 

 represented further to the south. If they are produced in 

 that direction they will be found to coincide generally with the 

 lie of the shores of Lake Taupo. The main line will corre- 

 spond with the eastern shores ; whilst the Orakeikorako line 

 will correspond with the western shore of the lake from Waihi 

 to the bold and precipitous headland of Karangahape — i.e., 

 south of Western Bay ; and the Eotorua line will correspond 

 with the western shores of the broad arm of the lake known 

 as "Western Bay. 



It will be noticed, however, that the coincidence is not 

 exact, the lines showing a tendency to converge as we ap- 

 proach the south, the point of convergence being Euapehu. 

 There can be no doubt that Euapehu marks the position of an 

 important centre with reference to the broader structural fea- 

 tm-es of the North Island. It is here, or near here, that the 

 line of elevation marked by the northern peninsula joins the 

 main axis or backbone of both islands. The line of the 

 western coast of the peninsula north of Auckland, if produced, 

 will be found to pass approximately through Euapehu. In 

 other words, the structural axes and dislocations of the coun- 

 try radiate from near Euapehu, and the manifestation of vol- 

 canic forces here is determined by its position with reference 

 to the great flexures of the earth's crust. 



The examination of these radiating lines cannot fail to 

 remind the geological reader of the system of cracks obtained 

 by Daubree during experiments on the fractures produced in 



