12 The Sea 
and may cause great damage on near-by shores, flooding en- 
tire towns and drowning the populations. In one such disaster 
100,000 lives were lost. A huge wave started near Lisbon in 
1755, traveled all the way across the Atlantic and when it 
reached the West Indies was still almost 20 feet high. 
A sudden collapse of a portion of the ocean floor would 
cause a dimple in the ocean’s surface, a phenomenon which 
geologists suspect has happened at least twice in the China 
Sea. The dimple would be filled by a shrinking circular wave. 
Heaven help a ship in the middle! 
Tidal waves are usually one hundred to two hundred miles 
in length—measured from one crest to the next—and several 
score feet high. On the open sea a ship might pass through a 
series of these waves without even noticing them because of 
their great length. Inasmuch as a tidal wave does not have 
anything to do with the tides, it is better to call it by another 
name. It is usually called tsunami, a Japanese word meaning 
STOTM WAVE. 
OCEAN VOLCANOES 
If you look at a map which shows where the world’s vol- 
canoes are located, you will see that most of them lie on the 
shores of the Pacific Ocean, and a smaller number are situ- 
ated along a line extending from Java through India, through 
the Mediterranean up to Iceland. This would suggest that 
volcanoes are associated with the ocean and that some might 
lie beneath the surface of the ocean. As a matter of fact it has . ) 
been established that the ocean floor does have volcanoes of 
its own and that these sometimes erupt. The molten lava and 
superheated gases coming into contact with the cold ocean 
water cause a tremendous explosion. Hot gases and vapor 
ee es 
