Tax returns and supporting documentation. The IRS has three years to challenge your tax returns, so you must keep them at least that long. It's wise to keep tax returns for at least six years, because if the IRS suspects you may have under-reported income, it has six years to challenge returns.
How is the Earth's crust related to tectonic movement? The convection currents in tectonic plates occur in the geosphere. The radioactive decay of elements is responsible for the heat deep within the earth, and this results in the creation of magma. Magma is a type of material that can be semi-fluid or completely fluid.
Answers: 1. Plate: a piece of the crust. 2. Theory of Plate Tectonics-theory that explains the formation/movement of the Earthâs crust. 3. Lithosphere: outermost solid part of the crust.solid, pieces, basalt, more dense, float 4. Asthenosphere-the partially melted part of the mantle that contains convection currents that move the crustal plates.5.. Theory of Plate Tectonics-theory that explains the formation/movement of the Earthâs crust. 3. Lithosphere: outermost solid part of the crust.