Printed from The Discovery of Hydrothermal Vents - 25th Anniversary
CD-ROM ©2002 Woods Hole Oceanographic Institution
EARLY CLUES: Evidence
Red Sea "Hot Brines"
very early hint of hydrothermal vents came in the 1880s when a Russian ship,
Vitaz, sampled waters 600 meters (2,000 feet) deep in the Red Sea
off the sacred city of Mecca. The deep waters were curiously warmer than
those at the surface. Sixty years later, a Swedish ship, Albatross, also
found water in the deep Red Sea to be a few degrees warmer than normal and
At first, scientists thought these hot brines, as they called
them, were formed by the hot equatorial sun. The sun heated and evaporated
surface watersleaving behind very salty (and therefore denser) waters
that sank to the bottom. That may have explained the high salt content of
the Red Sea bottom waters, but not the high temperatures.
In 1964, the British research ship Discovery found deep Red Sea waters
with temperatures of an astonishing 44°C (111°F). A year later,
Woods Hole Oceanographic Institutions R/V Atlantis II passed
through the Red Sea on the way to the Indian Ocean. Although it was four
days behind schedule, scientists aboard could not resist stopping to collect
a Red Sea sediment sample. The temperature reading was 56°C (133°F).
The chief scientist, Rocky Miller, did not believe his own eyes, so he repeated
the sampling, this time with a crude device to retrieve a sample of seafloor
sediment. They confirmed the 56°C temperature and pulled up black ooze
resembling tar that was too hot to touch.
The discovery encouraged the National Science Foundation to send the Woods
Hole ship R/V Chain back to the region a year later. The scientists once
again found warm deep waters. Even more amazing, however, were the sediment
cores they extracted from the seafloor.
The Red Sea sediments were filled with brilliantly colored layers rich in
copper, iron, manganese, zinc and other metals. The color variation
is fantastic: all shades of white, black, red, green, blue, or yellow can
be observed, WHOI scientists Egon Degens and David Ross wrote. Perhaps
some of the more colorful Indian sand paintings and Mexican rugs faintly
match these sediments in the variation and intensity of their colors.
The Red Sea is a young ocean with a mid-ocean ridge running through it.
Degens and Ross speculated in 1967 that the Red Sea phenomena they found
also might be seen in other areas where the seafloor is rifting apart. That
proved not only true, but also convenientbecause wars and political
turmoil in the Middle East made it increasingly difficult to take ships
back to the Red Sea.