Rocks Pages 94 98 in Science Plus Introduction

Rocks! Pages 94 -98 in Science Plus

Introduction to Rocks } Rocks can be classified into three groups: § § § Ø Igneous Sedimentary Metamorphic Rock cycle- constant cycle of old rocks turning into new rocks.

Igneous Rocks Igneous rocks- made from hardened lava or magma. } As they are formed crystals develop within the rock. } There are two types of igneous rocks. }

Igneous Rocks: Intrusive } } Intrusive rocks (plutonic rocks)- made from hardened magma (Below the earth’s surface. ) These rocks may be coarse or fine grained. Typically have large crystals. Examples include: § Granite § Syenite Above: Granite Right: Synite

Igneous Rock: Extrusive Rock (Volcanic rock) - made from hardened lava. (Above the earth’s surface) } Due to rapid cooling these rocks are usually fine grained or have tiny air bubbles. } Usually small crystals if any. } Examples include: } § Pumice § Basalt Pumice

Sedimentary Rock } } Sedimentary Rock- made from sediments, or pieces, of other rocks being pressed together. You can see the small segments of the other rocks within the larger rock. Lithification -the process by which rocks stick together because of pressure. There are three types of sedimentary rock. The "Finger of God", also known as Mukorob, a rock pillar in southern Namibia, photographed in 1979. A 34 meter column of sandstone rests on softer mudstone, which has eroded away to a narrow neck. The pillar eventually blew down in a storm on 4 December 1988.

Sedimentary Rock: Clastic rocks- made of broken pieces of weathered rock that have been pressed together. } Examples include: } § Conglomerate § Sandstone

Sedimentary Rock: Chemical rocks - made from minerals that have dissolved in water, the water has evaporated, and minerals have been left behind forming crystals. } Examples include: } § Travertine

Sedimentary Rock: Organic rock - formed from once living organisms that have been pressed together over a long period of time. } Examples include: } § Chalk § Limestone

Metamorphic Rockformed deep within the earth from a combination of heat and pressure. } There are two types of metamorphic rock. }

Metamorphic Rock: Foliated rocks - formed with bands or zones running throughout the rock. } Examples include: } § Gneiss § Slate

Metamorphic Rock: Nonfoliated rocks do not have bands or zones. } Examples include: } § § § Quartzite Coal Diamonds