Theory question 204
Rocks(a) Give two examples each of sedimentary and metamorphic rocks (b) Outline four major differences between sedimentary and metamorphic rocks
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(a) Sedimentary: sandstone, shale, limestone, clay, coal, conglomerate. Metamorphic: marble, slate, quartzite, gneiss, schist.
(b) Sedimentary rocks form from deposited and compacted sediments; metamorphic rocks form when existing rocks are changed by heat and pressure. Sedimentary rocks are in layers (strata); metamorphic rocks may be banded or foliated. Sedimentary rocks often contain fossils; metamorphic rocks rarely do. Sedimentary rocks are usually soft and porous; metamorphic rocks are harder and crystalline. Sedimentary rocks are non-crystalline; metamorphic rocks are crystalline.
Make each difference a direct comparison.