The Great Islands Under The Sea

THE GREAT ISLANDS UNDER THE SEA                                                                     continued



In recent years sonar has become so perfected that, through side-scan
sonar, a wider spread of the sea bottom can be examined with the same
sonar impulse. 

Another intriguing mystery has been clarified - that of the DRL (deep-
rising layer), which appeared on sonar as a false bottom that moved up
and down according to the time of day.  It was later established that
this movable bottom was composed of a mass of squid feasting on plank-
ton; the squid coming up at night to feed and descending back into the
depths during the day. 

At present, sonar can distinguish whales, schools of small fish, ships on
the surface or lying on the bottom or prowling submarines.  Sonar can
also pick out unusual formations on the bottom, sometimes man-made
and, through sonar photography, depict their reflected form. 

Sonar photography was employed on a search for the monster in Loch
Ness, in waters so murky, that vison could not penetrate.

Although the monster was not captured on sonar, prehistoric stone ruins
built at a time before the sea rose along with the water level of the enti-
re planet, were clearly indicated on the side-scan.

Because of its obvious use in mapping the sea bottom, it is evident that
high -technology sonar can be employed for locating the reamains of man-
made constructions such as cities, walls or pyramids on the ocean floor,
without the use of cameras with artificial lighting.

Except for some privately financed expeditions prospecting for such remains
in fairly shallow water, discoveries of architectural remains have been made
by chance and, generally, have not been followed up.

A notable case of this was pictures taken from a camera lowered from the
ANTON BRUNN research vessel for the purpose of photographing bottom fish
in the Nazca Trench off Peru, in 1965.  A chance photograph showed massive
stone columns and walls on the mud bottom, at a depth of one and a half
mile.

A further example was the experience of the French submersible ARCHIMEDE
which, in a dive off the continental shelf of the Bahamas, as it descended to-
waard the sea bottom, repeatedly bumped against a flight of giant cut-stone
steps, at the depth of 1400 feet.