■ METAMORPHIC—formed by intense heat and pressure. Those with high
quartz content form sandy soil (e.g., gneiss). Slate forms silty soil. Marble
forms limestone clay. Common examples: diamond, marble, asbestos,
slate, and anthracite coal.
■ SEDIMENTARY—formed by piling and cementing of various materials
(diatoms, weathered chemical precipitates, fragments of older rocks) over
time in low-lying areas. Fossils form only in sedimentary rock.
Figure 1.17 The rock cycle
MULTIPLE-CHOICE QUESTIONS
- The majority of the rocks in Earth’s crust are (A) igneous
(B) metamorphic
(C) sedimentary
