Ocean Forms - Ocean Worlds: The Story of Seas on Earth and Other Planets - page 49

explaining. There was a considerable space problem here. If the Atlan-
tic was widening, then all that crust had to go somewhere.
One of the ways to find that 'somewhere' was to increase the sur-
face area of the whole globe—that is, for the whole Earth to expand.
This idea had been expounded by Warren Carey, an Australian geolo-
gist in the 1950s. For some years both Heezen and Tharp subscribed
to this idea. Where did the matter come from? Here, matters were a
little vague, and Carey himself linked the expansion, a little mystically,
to the expansion of the whole universe. Others thought that the
power of gravity may be decreasing, causing the Earth and other
planets to expand from the release of pressure. The ultimate reason,
to the 'expansionists', did not seem to matter so much (after all, there
are lots of things that people don't understand). What did seem to
matter was the empirical fact, as they saw it, that the ocean basins
were getting bigger.
In the mid-1960s, there came the scientific revolution that was plate
tectonics (which Heezen and Tharp both soon joined). This explained
the continual expansion of the ocean crust at the mid-ocean ridges
that Heezen and Tharp had so entrancingly depicted, and the drift of
continents. New evidence also came into play. Magnetic 'stripes' had
been detected in the ocean crust by airborne surveys, symmetrically
disposed either side of the ridge. They reflected production of ocean
crust at the ridges successively through times when the Earth's mag-
netic field was like today's, with magnetic north at the geographic
North Pole, and times when the magnetic field had flipped so that the
magnetic pole was in the south (as was last the case a little under
800,000 years ago). This pattern had been noticed by the British
geologist Drummond Matthews and his student Fred Vine in the early
1960s, and was a crucial part of the puzzle. The plate tectonics
hypothesis squared all these circles simultaneously by continuously
producing ocean crust at the ridges, and then sliding it back into the