The Theory of Continental Drift

Continental Drift Theory Proposed by Alfred Wegener in 1912 250 million years ago, all of the continents were combined into one super-continent called “Pangaea” The continents gradually drifted apart to where they are today

“Puzzle Pieces” Continents look like they could be part of a giant jigsaw puzzle

Evidence to Support the Theory

Distribution of Fossils Plant and animal fossils found on the coastlines of different continents

Sequence of Rocks Same rock patterns found in South America, India, Africa, Antarctica and Australia

Ancient Climates coal deposits(Tropical plant remains) found in Antarctica Glaciers leave behind deposits and marks that show where they were located in Africa, South America, India, and Australia during the same time

Ancient Mountains Mountain ranges on five continents fit together on the jigsaw map

Problems With The Theory No mechanism for movement of continents Wind and currents could possibly move fossils Theory was not accepted by scientists

Continental Drift with Years

Plate Tectonics explain how continents move.                                                                                                                      Plate Tectonics explain how continents move.

The plate movements cause earthquakes.

Volcanic eruptions,

And mountain formation. Before and After And mountain formation.                                              

These events are most common along plate boundaries These events are most common along plate boundaries. A ring of active volcanoes called the ring of fire is found along parts of the Pacific Plate boundary.

Convergent boundaries The size of the Earth has not changed significantly during the past 600 million years, and very likely not since shortly after its formation 4.6 billion years ago. The Earth's unchanging size implies that the crust must be destroyed at about the same rate as it is being created, as Harry Hess surmised.

The Floor of the Earth's Ocean Basins                                                                                                                    The Floor of the Earth's Ocean Basins