It was not until the 1960's that the understanding of
the crust of the Earth, through plate tectonic movement, did it become
apparent how the rocks actually "recycled" themselves. Slowly
through time, the crust of the Earth moves and causes rocks to melt,
crystallize, weather, and get squished over and over through time. The
understanding of plate tectonics gave geologists an overall picture of
Today we are still refining how rocks are formed.
Even some rocks like granite (igneous) and chert (sedimentary) are still
in debate. As we understand more of the dynamics of the crust and its
interaction with the mantle and core, we might unlock the
mysteries of how rocks are formed.