Igneous rocks are formed when melted lava or magma cools and crystallizes, and their unique traits are based on this process. They are strong because their mineral grains grow together tightly as they cool, and their min... More »

Granite and basalt are excellent examples of coarsely grained igneous rocks. The coarseness of such igneous rocks is a result of magma becoming trapped beneath sediment and stone, which allows the liquid to cool at a slo... More »

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The two characteristics used to classify metamorphic rocks are foliation and lineation. These rocks are identified by the presence of certain mineral types and specific textures. More »

Igneous rocks are formed when magma crystallizes and solidifies. After this transition from liquid to solid, igneous rocks are classified as either intrusive or extrusive. More »

A plateau is formed by a process of geological uplift, either due to the collision of continental plates, pressure from magma below or the burial of land by volcanic lava and ash flows, resulting in a high, flat surface.... More »

Obsidian is a type of igneous rock created when felsic magma cools and hardens before it can form a crystalline structure. It is characterized by its smooth texture and extremely sharp edges. More »

Granite is an igneous rock that forms when a pocket of magma rises into the upper levels of the Earth's crust and slowly cools. Cooling slowly gives granite, which is composed mainly of feldspar and quartz, enough time t... More »