To get you thinking What natural process is responsible for the appearance of these rocks? Rocks and the Rock Cycle

Bell Ringer Name the 3 types of rock. Is one type of rock able to change into a different type of rock?

Rocks and the Rock Cycle Three Major Types of Rock Igneous Rock formed when lava or magma cools and crystalizes Sedimentary Rock formed from cemented sediments as a result from weathering and erosion Metamorphic Rock formed from igneous or sedimentary rocks that undergoes tremendous heat and pressure

Rocks and the Rock Cycle The Rock Cycle Any of the three major types of rock can be changed into another of the three types. Rock Cycle the series of processes in which rock forms, changes from one type to another, is destroyed, and forms again by geological processes Much of the rock in the Earth s continental crust has probably passed through the rock cycle many times during Earth s history.

Rocks and the Rock Cycle

Igneous Rock Formation Igneous rock form when lava or magma cools and crystallizes Magma molten rock below Earth s surface Lava magma that flows onto Earth s surface

Magma formation There are four main factors involved in the formation of magma. Temperature must be high enough to melt rock Pressure as pressure increases, the melting point increases Water content changes the melting point of rocks, as water content increases, the melting point decreases Mineral content changes the melting point of rocks

Mineral content Different minerals have different melting points. Rocks rich in iron and magnesium melt at higher temperatures Basalt Rocks rich in silicon melt at lower temperatures Granite

Partial melting Partial melting the process whereby some minerals melt at relatively low temperatures while other minerals remain solid This occurs because different minerals have different melting points (determined by the chemical composition of the mineral). When minerals melt, a certain type of magma is formed.

Partial melting What can we infer about the melting point of Quartz?

Fractional Crystallization When magma cools, it crystallizes in the reverse order of partial melting Fractional crystallization the first minerals to crystallize are the last minerals that melt When minerals solidify, a certain type of magma is formed.

Fractional Crystallization

Mineral Composition of Igneous rocks Intrusive rocks formed when magma cools and crystallizes below Earth s surface Generally contain larger crystals due to slower cooling of magma Intrusive rocks with large crystals are also called coarse-grained igneous rocks

Intrusive Rocks Granite Diorite

Mineral Composition of Igneous rocks Extrusive rock formed when magma cools and crystallizes on Earth s surface Generally contain smaller crystals due to faster cooling of magma Extrusive rocks with small crystals are called finegrained igneous rocks.

Extrusive Rocks Basalt Rhyolite

Mineral Composition of Igneous Rock There are three families of igneous rock Felsic rock igneous rock that is generally light in color and contains a lot of silica and feldspar Also called granitic rock

Pumice Rhyolite Granite

Mineral Composition of Igneous Rock Mafic rock igneous rock that is generally dark in color and contains a lot of magnesium and iron Also called basaltic rock

Scoria Basalt Gabbro

Mineral Composition of Igneous Rock Intermediate rock igneous rock that contains less silica than felsic rock but more than mafic rock

Obsidian Diorite Andesite

Texture Texture refers to the size, shape, and distribution of the crystals or grains that make up a rock Rhyolite (fine-grained) Granite (coarse-grained) Obsidian (glassy)

Porphyritic rocks Porphyritic texture rock characterized by large, well-formed crystals surrounded by finer-grained crystals of the same mineral or different minerals Diorite Andesite

Vesicular rocks Vesicular texture rock characterized by a spongy appearance Holes called vesicles are left behind as gases are trapped in thick magma Pumice Scoria

End of Igneous Rocks