RUNING HEAD: THE CONTINENTAL DRIFT THEORY 1 THE CONTINENTAL DRIFT THEORY 2 The Continental Drift Theory Benjamin Bogan SCI101-1303B-11: Introduction to the Sciences 9/16/13 The Continental Drift Theory The continental drift theory was developed by a German scientist, Alfred Wegener. In his book, The Origin of Continents and Oceans, he argued that the continental landmasses were drifting across the earth. He based this on the fact that the coast of Western Africa and South America looked like the edges of interlocking pieces of a jigsaw puzzle. He was thus convinced that the two were once part of an enormous single landmass known as Pangaea before it split apart. This was supported by geological and biological similarities in these areas. The development of this theory spearheaded a lot of research since many scientists did not agree with the idea. It led to more developments in the mid and late 20th century that proved that the landmasses were in constant motion. The additions on the Wegener’s evidence include paleomagnetism and seafloor spreading. Paleomagnetism is the study of the intensity and orientation of the Earth’s magnetic field as preserved in the magnetic orientation of certain minerals present in rocks. Many scientists have explored this field to find  evidence of continental drift. When hot magma rises and cools on the surface of the Earth, the minerals present become magnetized in alignment with the Earth’s magnetic field. Rocks formed at different places on the Earth’s surface have different magnetizations. Some rocks have magnetizations that do not agree with their position on the Earth but this is due to the wandering of the Earth’s magnetic poles. Using the alignment of magnetic minerals in the rock layers, the movement of the magnetic poles could be traced through the different geologic periods. The record of direction and intensity of magnetic field kept by certain minerals in rocks provide information on the past behavior of Earth’s magnetic field and the past location of tectonic plates. This is therefore an evidence of landmasses drifting. The magnetized minerals also show the direction to the Earth’s magnetic poles and provide a means of determining their latitude of origin. Polar wandering, which is the apparent movement of the magnetic poles illustrated in rocks, indicates that continents have moved. This is shown in polar wandering curves. The curves for North America and Europe have similar shapes but are separated by about 240 of longitude. The difference between the paths can be reconciled if the continents are placed next to one another. In 1962, Harry Hess, a geologist and an army commander during the World War II, added a geologic mechanism to account for Wegener’s moving continents. During his work to determine the deepest part of the sea, he discovered hundreds of flat-topped mountains that shaped the floor of the Pacif ...

1. RUNING HEAD: THE CONTINENTAL DRIFT THEORY
1
THE CONTINENTAL DRIFT THEORY
2
The Continental Drift Theory
Benjamin Bogan
SCI101-1303B-11: Introduction to the Sciences
9/16/13
The Continental Drift Theory
The continental drift theory was developed by a German
scientist, Alfred Wegener. In his book, The Origin of
Continents and Oceans, he argued that the continental
landmasses were drifting across the earth. He based this on the
fact that the coast of Western Africa and South America looked
like the edges of interlocking pieces of a jigsaw puzzle. He was
thus convinced that the two were once part of an enormous
single landmass known as Pangaea before it split apart. This
was supported by geological and biological similarities in these
areas. The development of this theory spearheaded a lot of
research since many scientists did not agree with the idea. It led
to more developments in the mid and late 20th century that
proved that the landmasses were in constant motion. The
additions on the Wegener’s evidence include paleomagnetism
and seafloor spreading.
Paleomagnetism is the study of the intensity and orientation of
the Earth’s magnetic field as preserved in the magnetic
orientation of certain minerals present in rocks. Many scientists
have explored this field to find evidence of continental drift.
When hot magma rises and cools on the surface of the Earth, the

2. minerals present become magnetized in alignment with the
Earth’s magnetic field. Rocks formed at different places on the
Earth’s surface have different magnetizations. Some rocks have
magnetizations that do not agree with their position on the Earth
but this is due to the wandering of the Earth’s magnetic poles.
Using the alignment of magnetic minerals in the rock layers, the
movement of the magnetic poles could be traced through the
different geologic periods. The record of direction and intensity
of magnetic field kept by certain minerals in rocks provide
information on the past behavior of Earth’s magnetic field and
the past location of tectonic plates. This is therefore an
evidence of landmasses drifting. The magnetized minerals also
show the direction to the Earth’s magnetic poles and provide a
means of determining their latitude of origin. Polar wandering,
which is the apparent movement of the magnetic poles
illustrated in rocks, indicates that continents have moved. This
is shown in polar wandering curves. The curves for North
America and Europe have similar shapes but are separated by
about 240 of longitude. The difference between the paths can be
reconciled if the continents are placed next to one another.
In 1962, Harry Hess, a geologist and an army commander during
the World War II, added a geologic mechanism to account for
Wegener’s moving continents. During his work to determine the
deepest part of the sea, he discovered hundreds of flat-topped
mountains that shaped the floor of the Pacific Ocean. He thus
proposed the sea floor spreading as an evidence of continental
drift. He proved Wegener’s idea right and clarified the
mechanism that broke the once joined continents. Sea floor
spreading is the process in which the ocean floor is extended
when two plates move apart forming cracks. Magma rises
through the cracks and seeps out onto the ocean floor like a
long thin undersea volcano. The sea floor moves in a conveyor
belt fashion thus explaining the phenomenon of the youngest
rocks being found only at the mid ocean ridges and they get
older as they move away from the ridge. Mantle convection at

3. plate boundaries of the sea floor is the driving force for the
motion of the floor and the continents themselves. When hot
magma rises, it cools and hardens upon reaching the surface. As
more magma rises the present sea floor is pushed aside making
the cold and dense rocks to sink and melt becoming magma
again. Sea floor spreading was developed due to the
understanding of the plate tectonic theory. At this zone where
two oceanic plates are moving away from each other, there
is the formation of new crust. This is known as a constructive
zone. Features such as the Mid Atlantic Ridge were formed due
to this thus clear evidence that continents are drifting.
The Wegener’s hypothesis of continental drift was earlier
rejected by scientists because it lacked a mechanism which
would have led the continents to drift. He did not explain
clearly how the continents moved which would have made it
easy to justify the time it took for the present day continents to
move to where they are. During that time it was also hard to
accept that the continents are in constant motion since no major
evident motion had been witnessed. His ideas were however
accepted in the mid-20th century with the development of other
geological evidence to supplement his earlier findings. The
plate tectonic theory illustrated clearly, explaining that the
Earth’s crust is made up of plates which are in constant motion
thus the drifting of continents. Other evidence such as the sea
floor spreading also made scientist to agree to Wegener’s
hypothesis. The other reason that may have led to rejection of
Wegener’s idea may be because it had not gone through the
scientific method of theory development thus it could not be
accepted without enough testing for approval. Scientists today
accept the movement of continents since the hypothesis was
tested and became a theory.
The scientific method is the act of scientists, collectively over
time, creating models of the natural world that can be verified
experimentally. The method involves observation, data

4. collection and recording and analyzing in a form that can be
duplicated by other scientists. The method involves four
important steps i.e. observation and description of phenomena,
hypothesis formulation to explain the phenomena, testing the
hypothesis by analyzing the results of observation or by
predicting and observing the existence of new phenomena that
follow from the hypothesis, and establishing a theory based on
repeated verification of the results. The hypothesis is only
regarded as a theory or law of nature if the experiments bear
out. If the experiments do not bear out, the hypothesis must be
rejected or modified. This method is helpful in the
understanding of the natural world since it is empirical. It
minimizes the influence of personal and cultural beliefs when
developing a theory.
The Wegener’s hypothesis of movement of continents was
rejected by scientists because it did not have a mechanism
which initiated the movement. They later accepted with the
development of plate tectonic theory which provided a
mechanism for continental drift. The Earth’s crust is made of
plates which move away from each other, towards each other
and slide past one another. The plates include both oceanic and
continental namely; Eurasian, Australian-Indian, Philippine,
Pacific, Juan de Fuca, Nazca, Cocos, North American,
Caribbean, South American, African, Arabian and the Antarctic
plate. These movements initiate the movement of continents due
to the forces involved. At the constructive zone for example, the
mantle convection is a driving force for the motion of the sea
floor and the continents. The forces of extension in this
boundary also lead to plate movement in opposite directions
thus movement of continents. Since most plates include an
entire continent plus a large area of the sea floor, when the
plates move, the continents move.
When two continental plates move away from each other, a rift
valley is formed. This is accompanied by volcanic activities on

5. the floor thus formation of volcanic features. In the case of
oceanic plates, mid oceanic ridges are formed. When an oceanic
plate collides with a continental plate, the oceanic is forced
underneath the continental plate, a process known as
subduction. This zone is characterized by volcanic and seismic
activities due to the energy generated. An example is the Pacific
ring of fire. When two continental plates collide, fold mountains
such as the Himalayas are formed.
The continental drift has today gained the support of scientists
due to evidence such as plate tectonics which were developed to
support the Wegener’s argument.
References
Edwards, J. (2005). Plate tectonics and continental drift.
London, United Kingdom: Evans Brothers.
Frisch, W., Meschede, M., & Blakey, R. C. (2010). Plate
tectonics: Continental drift and mountain building. New York,
NY: Springer.