Process:  - Rock begins as magma from a volcano - The magma cools - Crystals form and the magma become igneous rocks - The igneous rocks break down into sediment - Become sedimentary rocks - If subjected to heat and/or pressure from plate-tectonic activity the sedimentary rocks become metamorphic rock - The metamorphic rocks melt - Become magma again.  Perturbation hypothesis: suppose the heat source is less efficient happens, how will it affect LESS igneous rock forming.  Does the supposed perturbation have an effect (direct or indirect) on the process?

no