Name ____________________________________
Science 6
Date ___________
Quinn - ________
Part A: Continental Drift
a. What does the Theory of Continental Drift state?
b. What is the name of the scientist that proposed the Theory of Continental Drift?
c. What was Pangaea?
d. What are the names of the two continents that Pangaea separated into?
It has been proven that the Earth's present continents were once together as a Pangaea as seen
from:
1. __________________________________________________________
2. __________________________________________________________
3. __________________________________________________________
4.___________________________________________________________
a. How do the continental coastlines support the Theory of Continental Drift (Pangaea
Theory)?
b. Explain how fossil distribution supports the Theory of Continental drift.
c.
How do distinctive rock formations support the Theory of Continental Drift?
d. How does the location of coal deposits support the Theory of Continental Drift?
Part B: Convection Current
1.
What are convection currents?
2.
In which of Earth’s layers do convection currents happen?
3.
When convection currents flow in the mantle, they also move the ____________ .
Part C: Plate Tectonics
1.
What is a “plate” in geological terms?
2.
What does the Theory of Plate Tectonics state?
The Theory of Continental Drift
by Kenn Oberrecht
German meteorologist Alfred Wegener wasn't the first to observe similarities
among the continents that suggested the landmasses might have once been
connected. He was the first, however, to gather ideas and evidence into a palpable
theory, which he turned into a treatise entitled "The Formation of the Major
Features of the Earth's Crust (Continents and Oceans)."
In 1912, at age 32, Wegener must have seemed a brazen upstart to the esteemed members of the
Geological Association in Frankfurt and the Society for the Advancement of Natural Science in
Marburg when he delivered lectures on his theory that defied the geological thinking of the
time, which was based on the contracting-earth theory.
Continental similarities were being explained away with the notion that the continents had once
been connected by land bridges. The earth was cooling, according to the theory, and in the
process it was contracting, causing sea levels to rise and cover the land bridges.
Like others before him, Wegener noticed that the eastern outline of South America fit the western
outline of Africa like pieces of a jigsaw puzzle. He later noticed similar, if imperfect, fits among
the other continents. Geologists, paleontologists, and other scientists had collected a good bit of
evidence of matching but misplaced rocks, uncovered fossils in places they shouldn't have been,
and discovered evidence of astounding climatological changes.
Fossil remains of a prehistoric reptile known as the Mesosaurus had been uncovered on both
sides of the South Atlantic, yet the creature was no great swimmer. Plant fossils indicated that
tropical forests once existed only a few hundred miles from the North Pole. Glacial sediments
were found in sub-tropical areas. Coal seams and sedimentary rock formations on one continent
matched those on another. Mountain ranges that ended at one coastline seemed to begin again on
another.
Wegener theorized that a single supercontinent he called Pangaea existed sometime during the
late Paleozoic Era, 350 million to 225 million years ago. He maintained that the landmass broke
up and that its pieces dispersed and drifted, eventually reaching their present positions. Although
Wegener's theory had its weak points, his arguments were compelling. The idea of continental
drift certainly would explain many mysteries and answer a lot of questions. Nevertheless, the
scientific community wanted no part of it, and Wegener's theory was rejected from all quarters.
Prominent geophysicist Harold Jeffreys attacked Wegener's theory as specious. In his rejection of
the theory, Jeffreys focused on its greatest weakness: Wegener's failure to explain how continents
could move across the hard ocean floor.
Few scientists outside his native Germany ever accepted Wegener's theory or his later additions
to it and explanations of it. In fact, by the time of his death in 1930, Wegener's theory seemed
well on its way to obscurity. It would be several decades before new technology, new
discoveries, and new thinking would lead to the revolutionary theory of plate tectonics, which
incorporated Wegener's theory of continental drift and improved upon it.