Travel Reference
In-Depth Information
by fishing boats chasing a dwindling stock)? Yet far to the south, along the
sun-drenched coastline of Baja California, lie sedimentary strata identical in
lithology and fossil content to the drab green mudstones so typical of the
Upper Cretaceous of the Vancouver Island region. Coincidence? Or conti-
nental drift?
Continents do drift. Who would deny the ancient love affair of Africa
and South America, hoary continents that long ago dallied in theit global
bed until they were torn asunder by a restive earth. Cerebral researchers
needed complex machines to confirm the theory of continental drift. But the
ultimate evidence stares out at us from any map. We know now that the con-
tinents lie embedded in a pavement of more dense oceanic crust and that
both crust and continents skate across the surface of the earth on a more as-
tringent and liquid interior. These truths are now accepted hy all earth sci-
entists (the last holdout, Al Meyerhoff, has died). This revelation ushered in
one of the most profound scientific revolutions of our time, rivaling those
sparked by DNA in biology and by relativity and quantum mechanics in
physics. And as often happens after scientific tevolutions, once the battle
was over and the defenders of continental immobility routed through evi-
dence marshaled ffom paleomagnetics, paleontology, and paleoceanography—
in short, once the proponents of continental drift had won—the victors, like
so many conquering armies, claimed the spoils of war and went a little over-
board. In the aftermath of victory,
every
feature on the earth was seen as re-
sulting from some plate tectonic process. If continents could move, why not
every other feature on this wrinkled and ancient earth? A blizzard of specu-
lative papets about ancient continental configurations blanketed the land-
scape. Hypotheses outstripped the ability, and even the desire, to test them.
Backlash set in.
Quite properly, earth scientists began to demand convincing proof
rather than merely hypotheses concerning continental drift and the ancient
continental positions. Yet proof was often quite difficult to assemble. The
original evidence confirming the theory of continental drift came mainly
from ocean basins, not continents; it was the ocean basins that revealed
their long, linear underwater mountain chains, the spreading centers where
