Pond ond Smith. — On the Erujytion of Mt. Tarawera. 345 



little lakes, one of the most lovely blue colour, are also seen here, 

 both of which have been the scene of active hot springs in the 

 past. 



We now come, by following in the same direction, to Okaro 

 Lake, situated on the northern base of Kakaramea, and approach 

 the country which is the scene of the late eruption. Passing 

 this over for the moment, merely noting that Eotomahana is 

 directly in the same line of country, we find tlie Tarawera, 

 Euawahia, and Wahanga Mountains, all formed of solid trachy- 

 tic and rhyolitic rocks, and at their northern base come to the 

 hot springs of the Tarawera River, which are continued down 

 its course at intervals for several miles. This part of the vol- 

 canic belt is also marked by the old extinct volcano of Mount 

 Edgcumbe, with its double crater and the hot springs. Near 

 Te Teko we find, in Whale Island, situated 6 or 7 miles off 

 Whakataue, another group of hot springs, and close to them the 

 signs of former thermal action on Piurima Eocks, which have 

 been described by Major Mair in vol. v., page 151, of the 

 " Trans. N.Z. Inst." ; and, lastly, marking the most northerly 

 point of activity. White Island, an active volcano, but now in 

 the solfatara stage. 



A glance at the map will show that the points of activity 

 just described follow a fairly straight direction — north-east and 

 south-west — and evidently mark a line of weakness in the 

 Earth's crust, where the heated interior most readily finds a 

 communication with the surface. But, in addition to this line, 

 there are numerous other places on its flanks where hot springs 

 and other indications of activity are found, as at Te Niho-o-te- 

 Kiore on the Waikato, Eotorua, Eotoiti, Eotoma, Eotoehu, 

 Maketu, and Mayor Island, all within a few miles of this central 

 line. 



Besides the places where these indications of volcanic action 

 are present in a state of activity, we find that the whole country, 

 for many miles on both sides, is composed of materials which 

 owe their origin to volcanic action. Vast lava streams and 

 sheets are visible, either as forming the hills or lying hidden 

 under immense deposits of pumice, as on the Kaingaroa Plains, 

 which are nearly everywhere underlain by a sheet of lava, or its 

 accompanying mass of tufaceous rock derived from the same 

 source. Isolated hills, built up of trachytic and rhyolitic rocks, 

 denoting old volcanic necks, are common everywhere. The 

 pumice which has been ejected by the ancient volcanoes covers 

 an enormous extent of country, stretching north-easterly from 

 Euapehu to near Gisborne, where it is found as a thick layer on 

 tops of the highest hills ; and to the westwards, following the 

 river valleys for many miles. We know that the plains of the 

 Waikato are formed almost entirely of fine pumice-sand brought 

 down fi'om the central area, either by rivers or by the wind, or 



