Explain 2 features of a pluton/surrounding country rock that may influence the width of themetamorphic aureoles

When a pluton (essentially a large pocket of magma) intrudes into rock, the heat from the pluton 'bakes' the surrounding rock- remember that heating a rock to high temperatures will initiate contact metamorphism. The zone of metamorphic rock around a pluton is called the metamorphic aureole. One feature of a pluton that has an influence on the size of its metamorphic aureole is the size and extent of the pluton itself. Larger plutons holding a greater volume of magma will produce more heat than a pluton of smaller size and this increased heat will more effectively contact metamorphose surrounding country rock leading to a thicker metamorphic aureole around the pluton. A feature of the country rock that can affect the width of the metamorphic aureole is the composition of the rock. Clay based rocks such as shales are more susceptible to heat i.e will undergo metamorphic changes more easily when heat is applied producing a thicker metamorphic aureole. So if a pluton intudes into beds of shale there will be a larger aureole compared to a pluton of the same size intruding into sandstone or limestone.