A mineral is a naturally occurring usually inorganic solid that has a definite crystalline structure and chemical composition. Minerals are formed: As magma and lava cool By metamorphism From solutions Elements are pure substances that cannot be broken down into simpler substances by ordinary chemical means A substance made up of atoms or ions of two or more different elements joined by chemical bonds. Silicate minerals contain silicon and oxygen, normally in the form of silicate tetrahedrons. Nonsilicate minerals do not. Color- color of the mineral Streak- color of the powdered form of the mineral. (Remember: that if a scientist draws on a white tile with the mineral, this is how the streak is found.) Luster- way a surface reflects light Cleavage and Fracture- The way the mineral breaks/splits Density- measure of how much matter in a given amount of space. Hardness- mineral’s resistance to being scratched. Special Properties- any property specific to the mineral Igneous rock forms when magma or lava cools and hardens Sedimentary rock forms from compressed or cemented layers of sediment. Metamorphic rock forms from other rocks as a result of intense heat, pressure, or chemical processes. Weathering is the natural process by which atmospheric and environmental agents, such as wind, rain, and temperature changes, disintegrate and decompose rocks. Erosion is the process by which wind, water, ice, or gravity moves soil and sediment from one location to another. Deposition is the process in which material is laid down. The rock cycle is the series of processes in which rock forms, changes from one type to another, is destroyed, and forms again by geologic processes. Look in your book on page 78 for a diagram of the rock cycle. Uplift is the rising of regions of Earth’s crust to higher elevations. Subsidence is the sinking of regions of the Earth’s crust to lower elevations. A rift zone is an area of deep cracks that forms between two tectonic plates that are pulling away from each other. Crust Mantle Core Convection is the movement of matter due to differences in density that are caused by temperature variations; can result in a transfer of energy as heat. Convection takes place in the Earth’s mantle. Convection helps rocks move slowing in the mantle. (Cooler rocks sink and warmer rocks rise) Lithosphere Asthenosphere Mesosphere Outer Core Inner Core Scientists think that about 245 million years ago the continents were joined in a single large landmass that they call Pangaea. It’s important to understand that at one time scientists think that all the continents were connected and during millions of years the continents moved into their current locations. Sea-floor spreading is the process by which new oceanic lithosphere sea floor forms when magma rises to Earth’s surface at mid-ocean ridges and solidifies, as older existing sea floor moves away from the ridge. Older rock- far from ridge Newer rock- formed near ridge This theory explains how large pieces of the lithosphere, called plates, move and change shape. A tectonic plate is a block of lithosphere that consists of the crust and the rigid, outermost part of the mantle. Convergent- Two plates collide. Divergent- Two plates move away from each other Transform- Two plates move past each other horizontally Mantle Convection Ridge Push Slab Pull Anticlines- oldest layers of rock are in the middle of the fold. The youngest rocks are towards the outside. Anticlines are shaped like a: n In syncline folds the youngest rocks are in the middle and the older rocks are on the outside edges. Synclines are shaped like a: u Strike-Slip Faults Normal Faults Formed when rocks are under shear stress and at transform boundaries Formed when rocks undergo tension and at divergent boundaries Reverse Faults Formed when rocks undergo compression and at convergent boundaries Be able to label a diagram of each fault, with where the hanging wall, footwall and fault plane are! (Look on page 109) Folded Mountains- Form when rock layers are squeezed together and pushed upward. Usually at convergent boundaries Volcanic Mountains- Form when melted rock erupts onto Earth’s surface Fault-Block Mountains- Form when tension makes the lithosphere break into many normal faults. Along the faults, pieces of the lithosphere drop down compared with other pieces. The pieces left standing form fault-block mountains. Earthquakes are ground movements that occur when blocks of rock in Earth move suddenly and release energy. Label #6 page 116 in your book. Know that the Focus is the point underneath the Earth The Fault Line is the line between both of the plates The Epicenter is on the Earth’s surface. Label #5 on page 126 in your book. Know this! Know magma is underneath the Earth & lava is when it has reached the Earth’s surface Shield Volcanoes- Broad base, gently sloping sides, and form from mild eruptions. Cinder Cones- Steep volcano formed from violent eruptions Composite Volcanoes- Alternates between mild and violent eruptions. Divergent boundaries Convergent boundaries Hot Spots