Geology Reference
In-Depth Information
Driving Pangaea Apart at the Seams
Geologists have a good record of rock-forming events and processes during the Mesozo-
ic. The details of earth's geologic history become more detailed in more recent rock lay-
ers because the rocks have not been as deformed as older rocks (those of the Paleozoic
and Precambrian eras) have. The Mesozoic rock layers provide scientists with a huge
amount of information about the development of the modern continents.
One continent becomes many
When the Paleozoic era ended around 250 million years ago, the earth's landmasses
were connected, forming a single supercontinent called Pangaea (which I introduce in
Chapter 19). Pangaea was surrounded by a single large mass of water called the
Panthalassa Ocean.
The modern continents were arranged to form Pangaea as illustrated
in Figure 20-1, stretching from pole to pole and centered on the equator.
Figure 20-1:
The
arrangement of
modern continents
when they formed
Pangaea.
As the Mesozoic era began, large portions of the southern part of Pangaea (at the South
Pole) were still covered in the glaciers that developed during the cold climate of the pre-
vious era.
Fifty million years later, two sections of Pangaea —
Laurasia
and
Gondwana
— began to
separate. These two sections are illustrated in Chapter 8 (refer to Figure 8-6). In that
chapter I explain how the geological evidence of Gondwana is what inspired the geolo-
gists who developed early ideas about plate tectonics theory.
