Figure 6.1 Relative abundance of igneous rocks in the earth's crust (from General Geology (5th ed.), by Foster, Merrill Publishing Co., 1988).

Figure 6.2 Relative abundance of metamorphic rocks in the earth's crust (from General Geology (5th ed.), by Foster, Merrill Publishing Co., 1988).

Figure 6.3 Relative abundance of sedimentary rocks in the earth's crust (from General Geology (5th ed.), by Foster, Merrill Publishing Co., 1988).

Figure 6.4 The rock cycle. Originally proposed by James Hutton, the rock cycle illustrates the role of the various geologic processes which act to transform one rock type into another (from The Earth - An Introduction to Physical Geology (2nd ed.), by Tarbuck & Lutgens, Merrill Publishing Co., 1984).




Figure 6.5 The rock cycle as it relates to the plate tectonics model (from The Earth - An Introduction to Physical Geology (2nd ed.), by Tarbuck & Lutgens, Merrill Publishing Co., 1984).