Geology Reference
In-Depth Information
army. Shot through the neck during the Belgian campaign, Wegener was relieved of front-
line duty and permitted to devote his convalescence to study.
Wegener, like many of his predecessors, was struck by the apparent fit of continents
across the Atlantic Ocean, though many scientists had dismissed the match as coincidence.
Wegener cast a wider field of view and realized that similar fits could be seen in the varied
coastlines of East Africa, Antarctica, India, and Australia. Indeed, all of Earth's contin-
ents could be elegantly clustered together to make one supercontinent, which he dubbed
Pangaea (from the Greek for “all lands”). Wegener and a handful of like-minded support-
ers also cited evidence from recently published geological surveys of coastal regions of
Europe, Africa, and the Americas—treatises that revealed tantalizing correlations across
thewideexpanseoftheAtlantic.Greatminingdistricts,suchastheextensivegoldanddia-
mond reserves of Brazil and South Africa, appear as a single large deposit when the con-
tinentsarejuxtaposed.Similarly,rocklayersbearingthedistinctivefossilfern
Glossopteris
and the extinct reptile
Mesosaurus
line up almost exactly. Such detailed geological and pa-
leontological correlations could not be simple coincidence, he argued.
Wegener's continental drift hypothesis first appeared in print in 1915. Three subsequent
German editions, each more detailed than the last, as well as a 1924English translation en-
titled
The Origins of the Continents and Oceans
and many other editions, followed. New
data poured in to support the idea that continents had once been joined together. In 1917
a committee of paleontologists cataloged more than a dozen instances of distinctive fossil-
bearing strata matching up across the oceans—data they interpreted as requiring some sort
of ancient land bridges. South African geologist James Du Toit, who was especially en-
amored of Wegener's ideas, obtained a grant from the Carnegie Institution to visit eastern
South America. He recorded more examples of transoceanic matchups: striking instances
of identical minerals, rocks, and fossils.
Yet despite the accumulating data for continental alignment, the Earth science commu-
nitywasunmoved.Lackingaplausiblemechanismforcontinental-scalewanderings,many
geologists were openly contemptuous of Wegener's conjectures. They were bolstered in
thesecriticismsbyNewton'sfirstlawofmotion,whichstatesthatnothinghappenswithout
a force. Until an epic force of global scale could be invoked, continental drift would be
viewed as little more than a crackpot idea by a geological amateur. Cambridge physi-
cist Harold Jeffreys summed up the British viewpoint in 1923: “The physical causes that
Wegener offers are ridiculously inadequate.” Geologists in America were equally uncon-
vinced. Rollin T. Chamberlin of the University of Chicago's geology department blasted
continental drift at a 1926 symposium: “Wegener's hypothesis in general is of the foot-
loose type, in that it takes considerable liberty with our globe, and is less bound by restric-
tions or tied down by ugly facts than most of its rival theories.… If we are to believe We-
