formation of steam can occur at such depths, but the water heated above its critical temperature only attempts to ascend by virtue of its diminution of gravity, whereby it is naturally soon mixed with the practically freezing bulk of water of the deep sea. The submarine effusions of lava are wont to take place in complete quietude in a similar manner. According to Bergeat, such submarine eruptions have taken place, for example, at a depth of 700 to 1000 m. in the years 1888, 1889 and 1892, in the neighbourhood of Vulcano,
_-_figure_24.jpg)
Fig. 24.—Map of the oceanic sediments, after Krümmel.
1. Red clay. 2. Radiolarian ooze.
and have led to a rupture of the cable from Lipari to Milaggo, which was the reason that they were first noticed at all. It is a well-known characteristic of such submarine eruptions that they are practically noiseless in their effects.[1]
The depths of the three great oceans are not nearly the same. Kossinna[2] from Groll’s charts calculated
