The alternative explanation is that the glaciers rose from the sea. This is not likely. The age of the ocean floor increases away from the mid-ocean ridges. The age of ocean materials as a whole does not compare with the age of land materials. If spreading has taken place, this is what one would expect.
Magnetic studies indicate that the continents have moved and the ocean floor has spread.
Rocks forming from magma would indicate the magnetic field at the time of their creation. The ocean floor materials display a banding pattern. As one moves away from the mid-ocean ridges, these bands indicate changing magnetic directions. Mountain building and plate destruction zones are located where one would expect them according to continental drift theory. For example, North America has a western chain of mountains because it is moving in a westerly direction.