TECTONICS
, ALFRED WEGENER- CONTINENTAL DRIFT
Father of the ‘continental drift’ = theory was disproved until modern equipment could be used to prove
it
CONTINENTAL DRIFT
➔ 17th century - people realised South America and Africa looked like they should fit together
➔ 1912- Alfred Wegener proposed the theory of continental drift (all together= pangea)
➔ Wegener used fossils + geological evidence to suggest this
EVIDENCE OF CONTINENTAL DRIFT
➔ Fossils
➢ Fossils of the same green plants= found on almost all continents= suggests they
once had a similar climate
➢ Fossils of tropical plants- found on Antarctica and on islands in the Arctic ocean =
suggests they may have been much warmer
➔ Glacial Evidence
➢ About 300 million years ago= glaciers covered the southern hemisphere= patterns
they have travelled do not make sense unless arranged in the same way suggested
by Wegener
➔ Geology
➢ Mountain ranges contain similar rock and formed at the same time- Wegener theory=
mountains lined up into 1 major range
➔ Rock evidence
➢ Wegener map= explains matching rocks found oceans apart
PROBLEMS WITH WEGENER’S THEORY
➔ Could not explain what caused the continents to move
➔ Wegener collected substantial evidence but could not explain the mechanism responsible for
the motion
PALEOMAGNETISM
Paleomagnetism- study of the past changes in the Earth’s magnetic field (determined by rocks,
sediment + archaeological records
➔ Every 400000 years or so = Earth’s magnetic fields change direction = north + south pole
swap
➔ Lava cools + becomes rock, minerals inside the rock line up with the Earth’s magnetic
direction (polarity)
➔ Scientists found the same pattern of magnetic direction on either sides of the ridges
➔ Used to determine historical periods of large scale volcanic activity
, ALFRED WEGENER- CONTINENTAL DRIFT
Father of the ‘continental drift’ = theory was disproved until modern equipment could be used to prove
it
CONTINENTAL DRIFT
➔ 17th century - people realised South America and Africa looked like they should fit together
➔ 1912- Alfred Wegener proposed the theory of continental drift (all together= pangea)
➔ Wegener used fossils + geological evidence to suggest this
EVIDENCE OF CONTINENTAL DRIFT
➔ Fossils
➢ Fossils of the same green plants= found on almost all continents= suggests they
once had a similar climate
➢ Fossils of tropical plants- found on Antarctica and on islands in the Arctic ocean =
suggests they may have been much warmer
➔ Glacial Evidence
➢ About 300 million years ago= glaciers covered the southern hemisphere= patterns
they have travelled do not make sense unless arranged in the same way suggested
by Wegener
➔ Geology
➢ Mountain ranges contain similar rock and formed at the same time- Wegener theory=
mountains lined up into 1 major range
➔ Rock evidence
➢ Wegener map= explains matching rocks found oceans apart
PROBLEMS WITH WEGENER’S THEORY
➔ Could not explain what caused the continents to move
➔ Wegener collected substantial evidence but could not explain the mechanism responsible for
the motion
PALEOMAGNETISM
Paleomagnetism- study of the past changes in the Earth’s magnetic field (determined by rocks,
sediment + archaeological records
➔ Every 400000 years or so = Earth’s magnetic fields change direction = north + south pole
swap
➔ Lava cools + becomes rock, minerals inside the rock line up with the Earth’s magnetic
direction (polarity)
➔ Scientists found the same pattern of magnetic direction on either sides of the ridges
➔ Used to determine historical periods of large scale volcanic activity
