1. First Proposed by Alfred Wegener in 1915
Continental Drift
First Proposed by Alfred Wegener in 1915

2. The Earth’s crust is divided up into continental and oceanic areas
Continental areas cover 33% of the earth’s surface
Oceanic areas account for 67% of the Earth’s surface
The proportion of continental areas has increased through geological time
The positions of the continents and oceans have changed through geological time

3. The Internal Structure of The Earth

4. Evidence For Continental Drift Palaeo-Climates and Lithologies
Jig-Saw Fit
Tectonic Fit
Geological Fit
Glacial Deposits
Palaeo-Climates and Lithologies
Fossil Distributions
Palaeo-Magnetic

5. Jig-Saw Fit of Opposing Continental Coastlines
Fit of continents around the Atlantic Ocean
Generated by matching the continental shape at 500 fathoms
If the continents had once been joined, how can the present day gaps and overlaps be explained?
Coastal erosion and deposition since continental break up
Changes in sea level (eustatic change) or land level (isostatic change) since continental break up
Eastern South American and West African coastlines show the best jig-saw fit
Largest Overlap
Largest Gap

6. Jig-Saw Fit of Opposing Continental Coastlines
The Red Sea is a very young ocean, less than 30 million years olds
The African and Arabian Plates can be fitted back together if the Red Sea is closed

7. Geological Fit of Opposing Continental Coastlines
Cratons are areas older than 2000 Ma
Areas of Geological Fit across Continents
This suggests that Africa and South America were part of the same land mass 2 billion years ago

8. Geological Evidence from Gondwanaland

9. Geological Fit of Mountain Belts across former Oceans
Approximate position of the UK at this time
Iapetus Ocean in late stage of closure during the Lower Palaeozoic
Sediments from the floor of the Iapetus Ocean were uplifted, folded and faulted as continental collision occurred in the Late Siluruian and early Devonian
Directions of Plate Movements

10. Geological Fit of Mountain Belts across former Oceans
The Caledonian Fold Mountain Belt forms a linear chain that extends from North America, through Canada and continues into the UK, Greenland and Scandanavia
These mountains formed 400 to 450 million years ago following the closure of the former Iapetus Ocean
Since their formation the Caledonian Fold Mountains have been fragmented and dispersed onto different continents

11. Tectonic Fit of Mountain Belts across former Oceans

12. Tectonic Fit of Mountain Belts across former Oceans
Caledonian
Hercynian
Appalachian
Cordilleran
Andean
Transatlantic
Tasman
Ouchita
Urallian
Mauritanide

13. Glacial Evidence from the Permo-Carboniferous Glaciation
If Continental Drift has not occurred, then the Ice Sheet would have extended from the South Pole to the Equator!
Areas of Glacial Deposits
A major Glaciation occurred during the early Carboniferous and today large areas of glacial deposits from this event are found in South America, Africa, India, Australia and Antarctica.

14. Glacial Evidence from the Permo-Carboniferous Glaciation
Ice flow directions from glacial striations indicate ice spreading from a central point in all directions
When the continents of the Southern Hemisphere are fitted back together the Ice Sheet assumes a much more realistic size
Areas where ice deposits occur match up and continue across continental boundaries

15. Evidence from Palaeo-Climates and lithologies
Rocks in Scotland dated 700 million years old are Tillites
Tillite is boulder clay that has been turned into hard rock (lithified)
These deposits are forming beneath glaciers and ice sheets today

16. Evidence from Palaeo-Climates and lithologies
Suggests that Scotland had an Ice Age style climate during the Precambrian 700 million years ago
It is likely that the UK was located close to the South Pole at this point in time
Boulder Clay revealed by retreating ice

17. Evidence from Palaeo-Climates and lithologies
Rocks in Scotland of Devonian age, 380 million years ago are red sandstones and breccio-conglomerates rich in iron oxide
Similar rocks today are forming in hot desert environments that are a mix of dune fields and temporary stream channels or wadis
This suggests the UK had a hot, arid climate million years ago
Breccio-conglomerate with iron oxide cement
Red sandstones at Siccar Point, near Edinburgh

18. Evidence from Palaeo-Climates and lithologies
The UK was situated in the Southern arid belt during the Devonian (380 Ma) Latitude 20° South of the Equator on the same latitude as the Great Australian Desert

19. Evidence from Palaeo-Climates and lithologies
During the Carboniferous Period 345 to 280 million years ago the UK experienced a hot tropical climate as it was drifting from the southern hemisphere across the equator into the northern hemisphere
Typical limestone reef environment common in the UK during the Carboniferous
The seas were warm shallow and tropical and favoured the growth of coral formations along with extensive deposits of limestone
Carboniferous Limestone, Malham, Yorkshire

20. Evidence from Palaeo-Climates and lithologies
Carboniferous swamp dominated by horsetails, ferns, gingkoes and cycads. This dead plant material decomposed to form coal deposits in the UK, USA and across Europe
The Okefenokee Swamp in Florida, USA. This is a modern coal forming environment and is around 7000 years old

21. Evidence from Palaeo-Climates and lithologies
The Carboniferous period is so called because the rocks are rich in carbon.
Dead vegetation accumulated in tropical swamps which were frequently inundated by the sea. Sediments were deposited on top which preserved the organic matter, later transformed into coal by further burial.
Trees from a Carboniferous Swamp
Anthracite and Bituminous Coal
Open Cast Coal Mining

22. Evidence from Palaeo-Climates and lithologies
Rocks in Devon of Permian age (260 Ma) are well sorted desert sandstones with reddish brown iron oxide cement
The UK was located in the Northern arid belt at this time and had a climate very similar to that of the Sahara Desert today
Palaeo-wind directions from the rocks in Devon match the prevailing wind direction in the Sahara today (North Easterlies)
Desert sandstones with red iron oxide cement, Exmouth, Devon

23. Evidence from Palaeo-Climates and lithologies
The UK experienced a hot, arid climate similar to that of the present day Sahara about 270 Ma The UK was located at latitude 30° North at this time

24. Evidence from Palaeo-Climates and lithologies
Britain continued to drift northwards from around 30° North million years ago to its current position of 51° to 55° North today.
Between 1.9 million and 10,000 years ago the UK experienced an Ice-Age climate once more (The Pleistocene Glaciation). The evidence for this in erosional landforms such as corries, aretes and U shaped valleys and also depositional features made of boulder clay such as drumlins, terminal, medial and lateral moraines.

25. Evidence from Palaeo-Climates and lithologies
Age in Millions of Years
Rock Types
Climate
Latitude
1.9 to 0.01
Boulder Clay
Glacial
51°- 55° N
270 to 250
Desert Sandstones and Breccias
Hot Desert
20° - 30° N
330 to 300
Limestones Coral Reefs Coal
Equatorial
10° N – 10° S
390 to 410
20° S - 30 ° S
700 to 720
60 °S - 70 ° S

26. Fossil Evidence from Gondwanaland

27. Fossil Evidence - Mesosaurus
10cm
Mesosaurus grew up to 1 metre in length
A freshwater crocodile-like reptile that lived during the Early Permian dated between 286 and 258 million years ago
Found as fossils only in Southern Africa and Eastern South America

28. Fossil Evidence - Mesosaurus
Distribution of Mesosaurus Fossils
Suggests that South America and Africa were joined during the Early Permian
Alternatively if Continental Drift has not occurred:
The same organism evolved independently on separate continents or
Mesosaurus swam across the Atlantic in breeding pairs to establish a second population group
First idea contradicts Darwin’s Theory of Evolution, second explanation is physiologically impossible

29. Fossil Evidence - Cyognathus
Cyognathus is an extinct Therapsid which was a mammal-like reptile.
Cyognathus literally means ‘dog jaw’
Large as a modern wolf
Lived during the Early to Mid Triassic period between 250 and 240 million years ago
Found as fossils in South Africa and South America

30. Fossil Evidence - Lystrosaurus
Lystrosaurus literally means ‘shovel reptile’
Dominant land vertebrate in the Early Triassic 250 million years ago
Thought to be herbivorous
Grew to approximately one metre in length and was stocky like a pig
Fossils found in Antarctica, India and South Africa

31. Fossil Evidence - Glossopteris
Glossopteris means ‘tongue’ in Greek and is named from the shape of its leaves
Leaf size 2cm to 30cm in length
Evolved during the Early Permian and went on to become dominant species throughout the period
Extinct at the end of the Permian
Found in Australia,South Africa,South America, India and Antarctica
Glossopteris was a woody, seed-bearing shrub or tree, some reaching 30m tall.

32. Palaeo-Magnetic Evidence
The Earth’s magnetic field is analogous to that of a bar magnet
The lines of magnetic force intersect the surface of the earth at 90° at the Poles and decrease in angle to 0° at the equator
Magnetic field properties are the same around each line of latitude

33. Palaeo-Magnetic Evidence
Magnetite is a magnetic mineral found as an accessory mineral in basic igneous rocks
As basalt cools, magnetite crystallizes and becomes oriented with respect to the earth’s magnetic field at that latitude on the earth’s surface
As basalt cools below the Curie Point (500°C) the magnetic pattern is locked into the rocks
Magnetite Crystal

34. Palaeo-Magnetic Evidence Compass needle mounted in the vertical plane
Magnetic inclination varies from +90° at the North Pole to -90° at the South Pole
Magnetic inclination of magnetite crystals in basalt can be measured by using a compass needle mounted in the vertical plane
The angle of inclination is an indication of the distance from the North Pole that the basalt was originally formed
Compass needle mounted in the vertical plane
Basalt pillow lavas

35. Palaeo-Magnetic Evidence
+90° at North Pole
0° at the Equator
-90° at South Pole N
Orientation of magnetite crystals
Arrow heads represents North S
Variations in magnetic inclination within the Earth’s Magnetic Field

36. Palaeo-Magnetic Evidence
Dip of +90° indicates the North Pole, Dip of 0° indicates it was formed on the equator 10,000 km away from the North Pole
By looking at the magnetic inclination of basalts of different ages from the same region it is possible to construct an ‘apparent polar wandering curve’ through geological time
The different inclinations will represent changing distances from the North Pole over time
Assumes the magnetic poles are fixed over geological time and records the apparent latitude drift of a continent

37. Palaeo-Magnetic Evidence
Magnetic inclination will be the same around any line of latitude
Only North-South movements of continents can be traced through geological time
Longitudinal or East-West movements cannot be detected using magnetic inclination
The assumption is made that the Poles do not shift position in any significant way over long periods of geological time
Assumes the continent has remained fixed over time and records the apparent wandering path of the pole

38. Reconstruction of Continental Drift through Time 1
Watch these instead!!
Late Precambrian 550 Million Years Ago

39. Reconstruction of Continental Drift through Time 2
Early Ordovician 490 Million Years Ago

40. Reconstruction of Continental Drift through Time 3
Late Ordovician to Early Silurian 445 Million Years Ago

41. Reconstruction of Continental Drift through Time 4
Mid Devonian 375 Million Years Ago

42. Reconstruction of Continental Drift through Time 5
All continents joined together as the supercontinent Pangea
Carboniferous 300 Million Years Ago

43. Reconstruction of Continental Drift through Time 6
Triassic 235 Million Years Ago

44. Reconstruction of Continental Drift through Time 7
Pangea starts to break up into a Northern landmass called Laurasia and a Southern landmass called Gondwanaland
Jurassic 195 Million Years Ago

45. Reconstruction of Continental Drift through Time 8
Laurasia and Gondwanaland have continued to break up and move apart over the past 195 million years
Late Cretaceous to Early Tertiary 65 Million Years Ago

46. Reconstruction of Continental Drift through Time 8
Present Day Position of the Continents

47. The End