Page:Scott's Last Expedition, Volume 1.djvu/494

316 This evening the Soldier tells me he has eaten his food, so I hope all will be well again.

Friday, June 16.—Overcast again—little wind but also little moonlight. Jimmy Pigg quite recovered.

Went round the bergs in the afternoon. A great deal of ice has fallen from the irregular ones, showing that a great deal of weathering of bergs goes on during the winter and hence that the life of a berg is very limited, even if it remains in the high latitudes.

To-night Debenham lectured on volcanoes. His matter is very good, but his voice a little monotonous, so that there were signs of slumber in the audience, but all woke up for a warm and amusing discussion succeeding the lecture.

The lecturer first showed a world chart showing distribution of volcanoes, showing general tendency of eruptive explosions to occur in lines. After following these lines in other parts of the world he showed difficulty of finding symmetrical linear distribution near McMurdo Sound. He pointed out incidentally the important inference which could be drawn from the discovery of altered sandstone in the Erebus region. He went to the shapes of volcanoes:

The massive type formed by very fluid lavas—Mauna Loa (Hawaii), Vesuvius, examples.

The more perfect cones formed by ash talus—Fujiama, Discovery.

The explosive type with parasitic cones—Erebus, Morning, Etna.

Fissure eruption—historic only in Iceland, but best