186 



CAPT. ~F. W. HUTTON ON THE 



easy, even for horses, to walk over it ; but it soon got soft, owing 

 probably to thawing. This mud deposit thins out very rapidly, the 

 thickest portion forming an oval, from Lake Okaro to beyond 

 Waitangi, ten or twelve miles long and five or six broad (see fig. 2). 

 Beyond this to the north it thins out gradually, and it did not fall 

 as mud much beyond Taheke. The following table shows this : — 



Papawera Plateau 



Wairoa 



Taheke 



Tauranga 



Mayor Island .... 

 Alderman Islands 



These differences between the two deposits are due to the 

 difference in the amount of water- vapour accompanying the different 

 eruptions. The steam from the openings on the mountain was com- 

 paratively small in quantity and did not fall as rain, being dissipated 

 in the atmosphere ; the ash was thus widely and evenly spread by 

 the wind. The enormous volumes of steam which escaped from the 

 craters on the plains condensed in the higher regions of the 

 atmosphere into rain-drops, which, in their fall, brought down large 

 quantities of ash that otherwise would have been carried further. 



Round the craters the deposit varies from 10 to 50 feet, but 

 appears to be very irregular ; for Prof. Thomas informs me that east 

 of the new lake, at the foot of Tarawera, the Manuka {Lepto- 

 spermuni) is not covered, and the thickness is not much more than 

 six inches. 



At Wairoa there are two layers of scoria separated by several 

 inches of mud, the lower of the laj^ers resting on the ground, and 

 the whole covered by about two feet of mud. These two scoria- 

 layers no doubt mark two outbreaks from the mountain, probably 

 when the two fissures were formed. The last outbreak must have 

 taken place between 3 and 3.30 a.m., or just before the explosion of 

 Rotomahana ; it seems therefore likely that the western fissure, 

 which runs towards Rotomahana, was formed at that time, or about 

 an hour and a quarter after the eastern fissure. 



The ash began to fall at the Southern Cross Petroleum Co.'s 

 "Works near Waiapu, at 4.20 a.m., and at the East Cape at 5 a.m., 

 at Rotoina and Rotoiti at 4 a.m., while it was not noticed at Tauranga 

 until 5.30 a.m. ; so that it passed much more rapidly to the east 

 than to the north. It ceased at Rotoiti at 10 a.m., and at Waiapu 

 between 10 and 11 a.m. ; but along the coast of the Bay of Plenty 

 it continued to fall until the afternoon. The correct time is, 

 however, uncertain ; for, being dry, the wind blew it up in clouds. 

 The night was generally calm, but at "Waiapu a strong N.W. wind 

 was blowing. At 3 a.m. at Wairoa a S.W. gale commenced, which, 

 between 4 and 6 a.m., extended all over the eastern part of the 



Distance from Thickness of 



Rotomahana. Deposit, 



miles. inches. 



, . 2± 39 



b 30 



. . 18 2§ 



. 43 1 



..63 i 



. . 90 A 



