These anomalies were not only symmetric about the ridge crest, but the pattern matched that of magnetic reversals known from continental basalt lava flows. After these data were reported, different research groups rushed to test the hypothesis by as many methods as possible. These observations are now combined to form the theory of plate tectonics. There appear to be 13 major plates that cover the globe. The plates can contain oceanic, or continental crust or both.
Continental crust resists subduction.
Continent-continent convergent boundaries form major mountains.