The picture of a splitting, spreading crust agrees with an idea proposed over fifty years ago by the German scientist, Alfred Wegener.

He argued that the continents originally were joined in a single mass and later drifted apart. The eastern edges of the Americas match the western edges of Europe and Africa fairly well.

Australia and other land bodies of the southern hemisphere also have nearly matching shapes, and although separated now by the sea, they have similar fossils.

The shapes of the world’s continents suggest that they were formerly joined. By rearranging the world map, we can fit the Americas in with Europe and Africa like pieces of a rough jigsaw puzzle.

Wegener’s idea is supported by evidence from ancient basalt rocks. When these rocks were forming from a rock melt, grains of iron minerals in them became magnetized and lined up like compass needles pointing towards the Earth’s north magnetic pole.

The grains froze in position, and have remained so to this day. But now the grains in some of the rocks do not point to the magnetic pole and on different continents the grains point in different directions.

Apparently, either the magnetic pole or the land masses-or both-have shifted. It is known that magnetic pole does shift; it is shifting today.

Even so, magnetic grains in rocks of the same age on different continents point in different directions.

Originally, all must have pointed in one direction towards the magnetic pole of that period of the Earth’s history.

Thus, it appears that land masses have indeed shifted. A few scientists are still not convinced, but the evidence is strong.

Some scientists think the continents were moved by currents in the mantle. Other believes that the Earth may be expanding as the interior heats up from radioactivity.

If this is so, the continents are gradually moving apart as the Earth expands-like spots on a balloon when the balloon is blow up.

In any case, the key to the puzzle lies under the ocean floor. As scientists go on exploring, they will uncover further secrets of the forces that change our world.

Migrating Continents