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BASALT

A dark volcanic rock rich in iron and magnesium minerals. Basalt is the most common volcanic rock on earth.

CLAST

A rock fragment or grain resulting from the breakdown of larger rocks.

CONGLOMERATE

A sedimentary rock made of a mixture of rounded pieces of other rocks.

DIKE

A sheet or wall-like mass of igneous rock that cuts across other rocks.

DROPSTONE

A rock that was carried along the base of a glacier and dropped, most commonly into a sedimentary layer, as the glacier melted.

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