The Great Islands Under The Sea

THE GREAT ISLANDS UNDER THE SEA continued

The Mid-Atlantic Ridge marks the tectonic-plate boundaries - those of
the North American, European and African plates.

It is also connected to the world's longest mountain range, 40,000 miles
long and extending one and a half times around the world. It generally
runs north to south in the mid-Atlantic and, after crossing between
Africa and Antarctica, turns northeast and crosses the Indian Ocean.

It is the world's longest and most active seismic area, especially active
in the North Atlantic area, where a triple
junction of tectonic plates occurs at the Azores and where volcanic ex-
plosions have rumbled and erupted for thousands of years.

Parts of this active triple junction, where tectonic plates are still pushing
under, over, away from, or grinding alongside each other, have been repro-
duced by side-scan sonar at various depths and contain intriguing details
on depth profiles.

The theory of tectonic plates makes the concept of Atlantis considerably
more believable. The continental-drift theory deals with millions of years of
leisurely separation of continents by horizontal drifting, while the tectonic-plate
theory implies the probability of vertical movement, volcanic eruptions and
seismic convulsions and explains how great islands can be alternately thrown
up or engulfed by the sea - a process still going on and which can be observed
and measured. It also would tend to substantiate the comparatively recent
age (1000 to 15,000BC) of some of the lava flows found on the sea bottom of
the Mid-Atlantic Ridge.