Geology Reference
In-Depth Information
Meeting at the equator
All these lines of evidence strongly support the connection of the southern continents
into a single, large landmass, but what about the continents of North America, Europe,
and Asia?
A South African geologist named Alexander du Toit expanded on Wegener's work by
gathering more geologic and fossil evidence during the 1920s and 1930s.He proposed
that in the past, Gondwana was situated at the South Pole (based on the evidence for
glaciation) and that another large landmass existed near the equator. He called this
equatorial supercontinent — composed of North America, Greenland, Europe, and Asia
—
Laurasia.
Figure 8-6 illustrates how Laurasia probably appeared.
Figure 8-6:
The
continents forming
Laurasia.
You can find more details about the supercontinents Pangaea, Gondwana, and
Laurasia in Chapters 20 and 21.
Searching for a mechanism
Even with all these lines of evidence, scientists were still skeptical of the idea of contin-
ental drift for one very important reason: No one had yet explained
how
the continents
moved.
