The Continental Drift Theory Lecture Notes

THE CONTINENTAL DRIFT THEORY
PANGAEA and PANTHALASSA
 PANGAEA comes from the Greek word “Pan” meaning “all” and “Gaea” meaning “land”
 PANTHALASSA comes from the Greek word “Pan” meaning “all” and “Thalassa” meaning “sea”

ALFRED WEGENER’S

a) His supercontinent was also known as the protocontinent which means “the first continent.”

The northern part of Pangaea was called Laurasia.

 North America
 Europe
 Northern Asia
 The southern part was called Gondwanaland
 Africa
 South America
 Australia
 Antarctica
 Indian subcontinent
 Arabian Peninsula

 Between Laurasia and Gondwanaland was the ancient ocean called Tethys.



EARLY IDEAS ABOUT CONTINENTAL MOVEMENT, MOVING CONTINENTS

EDUARD SUESS

 He suggested that there may have been land bridges that connected today’s southern continents.
 He based his idea on the fact that fossils of the same Glossopteris fern had been found in India, South America,
Southern Africa, Australia and Antarctica.


ABRAHAM ORTELIUS

 The noticeable fit of the South American and African continents


ROBERTO MANTOVANI

 similarities in geological formations in the Southern continents.
 He made maps of the former positions of the continents.
 continents were once joined together as a supercontinent whose parts drifted away from each other.
 This made Mantovani believed that the Earth is expanding.


FRANK BURSLEY TAYLOR

 Proposed continental movement, but without expansion
 He explained that the continents were dragged towards the equator by the gravitational pull of the moon.
 (forming the Himalayas and Alps on the southern edges of the continents.)


ALEXANDER DU TOIT

 Came up with the idea of the past supercontinent in the southern hemisphere.

, EVIDENCES FOR CONTINENTAL DRIFT

 Evidence from FOSSILS

MESOSAURUS

 Greek, meaning “middle lizard”
 a freshwater built lizard with four legs, long head and snout, with nostrils near its eyes.

MESOSAURUS

 It had a flattened tail for swimming. It was a carnivore that ate fish. Its fossils were found in South America and
South Africa.

Glossopteris

 (Greek glossa, meaning “tongue”)
 an extinct seed fern with large tongue-shaped leaves.
 Its tree grew to about 4 m.

Glossopteris

 It is the dominant plant of Gondwana.
 Fossils of this fern have been found in South America, Africa, Madagascar, Antarctica and Australia

Cynognathus

 (meaning “dog jaw”)
 was a warm blooded mammal like a reptile.
 a fast-moving carnivore with powerful jaws and dog-like teeth.
 Its fossil remains have been found in Africa and Argentina ( South America)


LYSTROSAURUS

 Also known as “the shovel reptile”
 a mammal like reptile about the size of a small dog.
 It had a pair of tusks and a snout turned upward.
 an herbivore
 Its nostrils and eye sockets are at the top of its head.
 Fossils of the lystrosaurus have been found in Africa, India and Antarctica.


EVIDENCE FROM CLIMATE MISMATCHES

 The discovery of fossils of tropical plants in the form of coal deposits in Antarctica is a mismatch that can be
explained by continental drift.
 Wegener concluded that this frozen continent must have been situated closer to the equator, where the climate
is warm enough for growth of lush and swampy vegetation.
 The presence of fossils of the glossopteris in present day polar regions and the occurrence of glacial deposits in
present day arid Africa such as the Vaal river, valley of South Africa,

EVIDENCE FROM GLACIERS

 Glaciers are huge extensive masses of ice that covered much of the Earth’s surface during ice ages.
 Glaciers leave marks on the surface, especially as they slowly creep. These marks called glacial grooves or
striations are carved into the bedrock.
 Grooves will be similar on continents that shared a glacier. Wegener believed that the glacial ice was centered on
the southern continents.
 Striations formed by the scraping of glaciers over the land surface indicated that Africa and South America had

been close together at the time of this ancient ice age .