460 Scientific Proceedings, Royal Dublin Society. 



that mountain is cracked and broken up to an extent to make- 

 crossing it very difficult. The north of Maounga-onga-onga is 

 also much cracked." 



In Dr. Hector's Report, page 2, is given a description of the 

 " Great Fissure." 



" This is the most remarkable and characteristic feature of 

 the late eruption and the chief origin of the disastrous results 

 which attended it. The fissure seems to commence in a narrow 

 rift at the northern end from the great rent which has been 

 formed in the south end of Tarrawera Mountain. This rent 

 is a most wonderful feature. It is not a slip from the mountain 

 side, but appears as if a portion of the mountain, measuring 

 2000 feet x 500 x 300 deep, had been blown out, leaving a ragged,, 

 rocky chasm, from which steam was being discharged in rapidly- 

 succeeding puffs. Its general direction, as far as could be ascer- 

 tained, is N. 50° E., which is the general line of direction that 

 would connect all the more active geysers between Tangariro and 

 White Island." 



It may be concluded from these details that the most signifi- 

 cant feature of the eruption and concomitant earthquakes was the 

 great fissure extending from Tarawera Mountain to Okara Lake, a 

 distance of about nine and a-half miles. The antipod of this fissure 

 projects itself on the map of Spain in the immediate vicinity of 

 the celebrated defile of Despehaperros in the Sierra Morena, which 

 connects the plateau of La Mancha with the great valley of Anda- 

 lucia, and from the gorge of which a magnificent view of the valley 

 is obtained. If the direction of the middle course of the Gruadal- 

 quiver be produced, it cuts the antipod of the northern extremity 

 of the fissure, that is, the point representing the antipod of Tara- 

 wera Mountain. 



There is thus brought into relation three very interesting lines 

 of earth Assuring — that traversing Spain from N.W. to S.E., that 

 constituting the axis of the volcanic zone of the North Island, New 

 Zealand, and the line of faulting which corresponds to the valley 

 of the Gruadalquiver. 



The very remarkable mine of Almaden (which forms part of a 

 great band of mineralized ground, extending in a line nearly east 

 and west between the village of Chillon and a point to the east of 

 Almadenejos), lies within the space covered by the projection of the 



