Marijuana on Federal Lands. Posted: January 27, 2014. With the legalization of marijuana in the State of Colorado, Mesa Verde National Park would like to provide clarification regarding the use of possession of marijuana on Federal lands.
Plate Tectonics. Plate tectonics is the movement of the Earth's crust through convection currents that occur in the mantle. Divergent plate boundaries occur where hot magma rises to the surface, pushing the plates apart. The mid-ocean ridges form at divergent plate boundaries.
Tectonic plates are composed of lithosphere, the rigid outer portion of the earth. With a thickness of about 100 km, the lithosphere is composed of an upper layer of crust (~7 km thick under the oceans, and ~35 km thick under the continents) and a lower, denser layer of the earth's upper mantle.