I.] GEOLOGICAL OBSERVATIONS 327 



still preserved. The last stage produced the small cone placed 

 asymmetrically in the upper crater, and from this cone the steam 

 now issues. 



Mount Bird, the low dome at the northern foot of Mount 

 Erebus, and Mount Terra Nova, the dome which joins Mount 

 Erebus to Mount Terror, are both undenuded and obviously 

 have craters at their summits, and therefore belong to the same 

 recent eruptions. 



Mount Terror, like Mount Erebus, is entirely covered by snow, 

 and as it is more conical than Mount Erebus it covers almost the 

 same area, though it is only a little over 10,000 feet high. The 

 cone is truncated, apparently by a crater half a mile in diameter, 

 and the sides of the cone, where bare of snow, display many 

 small parasitic vents. 



The rocks collected from this huge island are chiefly of volcanic 

 origin, but granites, sandstones, and rocks of a hypabyssal nature 

 are found as erratics in certain localities. 



The 'Southern Cross' obtained hornblende-basalts from a 

 bare rock-cliff, ten miles or so to the westward of Cape Crozier, 

 and Mr. Morrison brought back a portion of a basaltic bomb from 

 a boulder on the beach at Cape Crozier. Lieutenant Royds, 

 Dr. Koettlitz, and Dr. Wilson have all added to the collection 

 from this locality by bringing rocks on sledges over the ice 

 under very trying conditions. These rocks, with the exception of 

 the columnar olivine-basalt obtained by Dr. Wilson from the 

 so-called Crozier cliffs, do not differ materially from those 

 collected near the penguin rookery. The latter include granites 

 and sandstones, which are probably erratic, olivine-basalts from 

 recent lava flows, yellow trachytic rocks which occur as bosses 

 on the slopes of Mount Terror, and tuffs from below the lava flows. 

 From the 'V cliffs, Hogsback and the Sultan's Head, Mr. 

 T. V. Hodgson has supplied the expedition with vesicular basalts 

 and a great variety of palagonite-tuffs. Hutton Cliffs, near Turtle 

 Back Island, are composed of bedded tuff-rocks, which strike N.E. 

 and S.W. and therefore may be contemporaneous with the tuffs of 

 Sultan's Head. The Turtle Back is composed of fragments of 

 black basalt similar to that of Winter Quarters. Cape Royds, 

 Cape Barne, and the Skuary, three bare areas on the west side of 

 Mount Erebus, besides supplying boulders of granite and other 

 rocks, give us the basalt which contains lenticular crystals of 

 felspar in parallel orientation. Cape Royds consists entirely of this 



