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Rocks in the Earth's crust are classified by the way that they are formed.
Complete these questions about rock formation. (Use words from the drop-down lists.
a) ( igneous, sedimentary, metamorphic ) rocks are formed when molten lava from a volcano cools down.
b( metamorphic, igneous, sedimentary ) rocks are made from grains of rock that are cemented (stuck) together.
c) ( igneous, metamorphic, sedimentary ) rocks are made when heat and pressure change other types of rocks.
d) ( sedimentary, igneous, metamorphic ) rocks are made of layers and often contain fossils.