MOUNT EREBUS 217 



The final phase of this eruption of Erebus is shown on Plate LXVIIL, taken 

 by moonlight. 



It may be mentioned that during this eruption the barometer fell from 29*098 

 at 10 A.M. to 28-87 at 10 p.m. The glow on the steam column over Erebus was ob- 

 served more or less continuously from June until September. Soon after this there 

 was so much light in the sky at night that the glow, even if it had been there, would 

 scarcely have been visible. On November 27, 1908, Mr. James Murray has re- 

 corded another strong eruption of Erebus, of which he gives a sketch in " The Heart 

 of the Antarctic," vol. ii. p. 312. 



Mount Bird Geyser. It is of interest to note that between Erebus and Cape 

 Bird, apparently a few miles to the south of the latter extinct volcano, there is an 

 enormous geyser which spouts fitfully, but at long intervals of time. Judging by 

 the height to which the steam column ascends during an eruption it is by far the 

 largest geyser known in the world. The chief eruption was witnessed on June 17 

 at 8 P.M., when a remarkably dense white mass of what seemed to be cumulus cloud 

 was observed to the N.N.E. of our hut at a distance of perhaps 20 miles. At 11 p.m. 

 Mawson observed from the top of the anemometer ridge a tremendous outburst of 

 steam in the direction of Cape Bird. This mass rose rapidly from its starting point 

 at about 2000 feet above sea-level to probably at least 5000 feet above the sea. 

 We rushed for our cameras, but by the time we were able to get them to work the 

 great steam column had sunk down so as to look once more like a low isolated dense 

 cumulus cloud. The existence of this immense geyser, if it can be called such, 

 or possibly a parasitic cone of Mount Bird, is of considerable interest, as showing 

 that the line of crack along which volcanic energy is now active in the Erebus 

 region is not so much the east and west line of fracture, which extends from Cape 

 Crozier through Mount Terror, Terra Nova, and Erebus to Dry Valley, but rather 

 the north and south line of fracture extending from Erebus through Cape Bird. 



Other occasions when distinct eruptions of Erebus were observed were June 18, 

 1908, when at 12.20 P.M. a steam cloud was projected in an incredibly short space 

 of time for about 3000 feet above the summit of the mountain. At this time there 

 was a phenomenally low atmospheric pressure, slightly below 28 "3. 



On the 21st Erebus was again very active, the steam cloud being carried south- 

 wards on this occasion for a distance of at least 9 or 10 miles. On June 25, 1908, 

 at 4 a.m., Mawson observed two bright flashes, of what he described as flame, at 

 the summit of Erebus ; the first had the appearance as though a big bubble had 

 bm-st, releasing a lot of glowing gas. Black smoke rushed up to a height of about 

 2000 feet above the rim of the crater in about \\ minutes. The black cloud did not 

 appear until about 10 seconds after the bright flash. 



On June 30th, constant strong glows were observed over the summit of Erebus. 

 On July 6, 1908, at 11.30 a.m., we observed what ajapeared to be a fumarole erup- 

 tion from near the centre of the second crater of Erebus, but we could not be 



