CONTINENTAL DRIFT THEORY

Alfred Wegener

ACT.3A: REASSEMBLING THE PIECES

LET’S FIT IT!

Assembling a puzzle can reveal a hidden meaning.

Procedure: Choose a page of a magazine with

pictures. Cut the page of a magazine into not

more than 20pcs. Insert the pieces inside the brown

envelope. Trade the envelope with the other

groups. Try to fit the pieces of magazine

together.

ANSWER THE FF. QUESTIONS What evidence did you use to

put the pieces together? What features of the magazine

helped you to connect the pieces perfectly?

How do the lines of prints or texts in the help you to confirm that you have reassembled the magazine page?

How do your pieces serve as a model of CDT?

BRING THE FF.(BY GROUP) List of dominant species of plants and animals found in the continents before and after drifting away from each other

photocopy of the seven continents (letter size)

world map pair of scissors

ACTIVITY 4: DRIFTED SUPERCONTINENT

Tell the possible direction of motion of the continents as they drifted away.

Draw fossils of plants and animals as evidences found in the present continents that will help solve the puzzle in the fitting of the drifted continents.

Reconstruct and describe Pangaea.

Predict what will happen to the world as the continents continuously move.

PROCEDURE: Cut carefully the traces of the seven continents.

Sketch the dominant species of plants and animals found in the continents before and after drifting away from each other.

Put the cut-outs together. Answer: Q13-16.

PROCEDURE: Make sure that you put fitting edges

of the continents side by side to form the supercontinent Pangaea.

Answer: Q17-20 Compare Pangaea with the world

map. Now move one continent relative to

its current location. Observe carefully the direction of its motion as it assumes its current location and position. Record your observation.

PROCEDURE:

Do the same procedure to the other continents. Record your observations.

Answer: Q21

ANSWER: THINKING CRITICALLY: INFERRING

Coal deposits have also been found beneath the ice of Antarctica. But coal only forms in warm swamps. Use Wegener’s theory to explain how coal could be found so near the poles.

refer to Plate Tectonic Theory History PPT

CDT MAP

DRIFTING CONTINENTS

DRIFTING CONTINENTS

Continents were not stationary, but actually moving or drifting away from one another.

TOPOGRAPHIC EVIDENCE Inspection of any global

map will show that the edges of continents such as South America and Africa appear to match.

This apparent jigsaw-like fit is no coincidence - the two continents split apart from one landmass during the Cretaceous period, and oceanic crust developed in between them.

TOPOGRAPHIC EVIDENCE

TOPOGRAPHIC EVIDENCE

Map of a closed Atlantic Ocean showing the rifts that formed when Pangaea was split by a spreading center. The rifts on today's continents are now filled with sediment. Some of them serve as the channel ways for large rivers.

TECTONIC FIT The positions and ages of

tectonic features which occur on the various continental landmasses seem to join up.

Another line of evidence is the alignment of glacial striations (scratches caused by ice) in rocks caused by the movement of ice sheets over the southern continents during the Permian and Carboniferous periods.

STRATIGRAPHIC CORRELATION

Continents which were once part of the same landmass will show similar rock sequences along their margins up until the time when they split apart.

In the African and South American plates, similar freshwater rocks found along the continental margins can be correlated up until the end of the Lower Cretaceous, when continental rifting split the continents apart.

STRATIGRAPHIC CORRELATION

PALEONTOLOGICAL EVIDENCES

Fossils contained within stratigraphic sequences which are now located on different continents can indicate that the two landmasses were once joined.

Mesosaurus fossils found in early Permian freshwater shales in both Brazil and southern Africa

Glossopteris, Cygnonathus, and Lystrosaurus are among others

PALEONTOLOGICAL EVIDENCES

PALEO-CLIMATIC EVIDENCE

PALEO-CLIMATIC EVIDENCE

OTHER EVIDENCES

PALEOMAGNETISM

PALEOMAGNETISM

PALEOMAGNETISM

PALEOMAGNETISM

1950’s: discovery of ancient rocks had magnetic directions and inclinations that did not correspond with the present magnetic pole position.