Read and use the information in the passage to explain why plate tectonics is a scientific theory and not a scientific law.
Plate tectonic theory had its beginnings in 1915 when Alfred Wegener proposed his theory
of "continental drift." Wegener proposed that the continents plowed through crust of ocean
basins, which would explain why the outlines of many coastlines (like South America and
Africa) look like they fit together like a puzzle. Wegener was one of the first to realize that
the Earth's surface has changed through time, and that continents that are separated now
may have been joined together at one point in the past.
Evidence was also found that there were fossils of similar species found on continents that
are now separated by great distance. Other studies that examined climate in Earth's past,
revealed that glaciers covered large areas of the world which also are now separated by great
distances. These observations seemed to indicate that the Earth's lithosphere had been
moving over geologic time.
Wegener's ideas were very controversial because he didn't have an explanation for why the
continents moved, just that there was observational evidence that they had. Although
Wegener's "continental drift" theory was later disproved, it was one of the first times that the
idea of crustal movement had been introduced to the scientific community; and it laid the
groundwork for the development of modern plate tectonics.
As years passed, more and more evidence was uncovered to support the idea that the plates
move constantly over geologic time. Some of the evidences were that earthquakes,
volcanoes, and other geologic features responsible for changing Earth's surface are found in
distinct areas around the world, and those areas where at the edges of tectonic plates.