[ad_1]
The theory of continental drift suggests that all continents were once united into one supercontinent called Pangea, which drifted apart over time. Alfred Wegener first proposed this theory in 1912, but it was not widely accepted until the 1950s. Evidence such as identical fossils and minerals on separate continents, along with the theory of plate tectonics, support the theory of continental drift. However, some dispute the theory due to differing beliefs about the age of the earth and the fossil record.
The theory of continental drift is the theory that all continents were once united into one supercontinent, which scientists call Pangea. Over a vast period of time, the continents have drifted apart at their present positions. Alfred Wegener first argued for continental drift.
Wegener’s explanation of continental drift in 1912 was that the drift occurred due to the rotation of the Earth. This explanation and his theory were not widely accepted. Before Wegener, however, many had noted that the shapes of the continents appear to fit together, suggesting a schism in the past.
Prior to the 1950s, the concept of continental drift was, for the most part, not even considered plausible. In the 1950s and subsequent years, however, geologists began to entertain the theory, and by the 1960s, most geologists came to accept that the theory might be possible. Several factors point to the change in acceptance of the theory of continental drift.
The fossil record from separate continents, particularly on the periphery of continents, show the same species. Even the mineral samples along the supposed continental break lines are nearly identical. A few identical species exist on some continents, such as an earthworm common in both Africa and South America, suggesting that the species could not have arisen spontaneously on both continents without some variation.
The theory of continental drift also gained popularity thanks to the theory of plate tectonics. In short, plate tectonics suggests that the ocean floor began to spread and that continents existed on “plates” that moved in response to changing ocean floors. Perturbations on continents, such as earthquakes, were a response to shifting plates. This suggests that some points on the continents show almost constant, albeit tiny, motions.
For example, Point Reyes, which sits on the San Andreas Fault line in northern California, was measured as it moved slowly north at a rate of about half an inch (about 2.5 cm) per year. In fact, some geologists theorize that with continued movement, Point Reyes could eventually become an island.
Not everyone accepts the theory of continental drift for many reasons. One reason for the dispute is that the age of the earth is in dispute. Some creationists, for example, believe the earth is much younger than some geologists believe. Some of these creationists also don’t accept carbon dating as a way to determine the earth, or that the fossil record is as old as some scientists claim.
Most scientists, and those who don’t believe in creationism, accept the theory of continental drift, along with the theory of plate tectonics. Those who support the intelligent design theory also usually accept continental drift, but claim that a spiritual presence designed and created the earth. The theory of continental drift is now taught as an accepted theory in US public schools.
