Aparna Huzurbazar, age 11, of Winnipeg, Manitoba, Canada, for his question:
WHAT IS CONTINENTAL DRIFT?
Many earth scientists say that at some time in the far distant future California may tear away from the mainland and drift north toward Alaska. They also suggest that Africa and South America may move farther apart, enlarging the Atlantic Ocean, and that Australia will drift northward and eventually collide with Asia. All this is part of the continental drift theory.
The continental drift theory suggests that the world's continents once formed part of a single land mass called Pangaea. According to the theory, the continents have moved great distances and are still moving today.
About 200 million years ago, the continental drift theory says, Pangaea started to break up into two large land masses. The two large masses then broke into smaller parcels, and they began to drift with some moving in straight paths and other rotating. The smaller parcels are our present continents.
Earth scientists say the continents are still drifting with most moving about an inch each year and India moving two inches every year.
Father of the continental drift theory is a German meteorologist named Alfred Wegener. He developed the theory in 1912 and came up with the name Pangaea for the supercontinent in 1915. He showed that tropical plants once grew in Greenland and that glaciers once covered Brazil and Africa's equatorial regions. Other scientists rejected the theory, saying that no one could explain how the continents could move such great distances.
During the mid 1900s, earth scientists gathered information that tends to support the continental drift theory. Studies of ancient geologic findings show a connection between the mountains of the continents. The Appalachias, which run through the eastern part of the United States, may have been connected to the Caledonia mountain system, which runs through northern Ireland, Scandinavia and Scotland.
Adding supportive evidence to the continental drift theory are the scientists who study fossils. They have found fossils of similar land mammals in 100 million year old rocks of Asia, North America and Europe. It seems unlikely that similar animals could develop on widely separated continents.
Additional support for the continental drift theory came during the 1950s from scientists studying the magnetism in ancient rocks. Studies showed that certain rocks in Europe and North America were once positioned closer together. The difference in present locations matched the width of the Atlantic Ocean, giving strong indications that the two continents were once connected before the ocean formed between them.