Earth and Space Science. Semester 2 Review, Part 2

Transcription

1 Earth and Space Science Semester 2 Review, Part Chemical Weathering -The process that breaks down rock through chemical changes. Examples that cause chemical weathering include the action of water (Water dissolves rock.), oxygen (Iron combines with water and oxygen in a process called oxidation that produces rust; making a rock soft and crumbly.), carbon dioxide (CO2 dissolves in rainwater and in the air pockets of soil. The result produces a weak carbonic acid that can weather rocks like marble and limestone.), living organisms (Plant roots can produce weak acids that can dissolve rock.) and acid rain (Burning of coal, oil and gas for energy can pollute the air with sulfur, carbon and nitrogen compounds. The pollutants can react chemically with water vapor and produce acid rain that creates rapid chemical weathering.) Core sample Crystal shape Deposition Elements - A cylindrical shape cut out of a rock or earthen surface that geologists can examine and study. -In minerals, a repeated crystal pattern is evident throughout with similar faces, edges and corners. -The pattern is one of the criteria or properties that give a particular mineral its identity. -The process that follows weathering and erosion in the formation of a Sedimentary Rock. -Minerals and sediments are deposited in layers, often in the bottom of a body of water, followed by their compaction and cementation. -Natural and man-made substances with unique atomic structures that can be organized on the Periodic Table. -All minerals have a definite chemical composition. -They either contain a pure element like silver or gold or have compounds of elements in proportionate amounts like the silicates. -The silicates are the most common minerals found on or in the crust. -Silicate minerals are made of crystals formed by silicon and oxygen compounds.

2 Compounds Erosion Foliation Hardness Igneous Landform Lithification - A substance formed by one or more elements that are chemically combined. -Most minerals are compounds of one or more elements. -The breakdown (Weathering (physical and chemical)) and transportation of sediments, minerals and rocks by water, wind or ice. -When crystal grains of a Metamorphic Rock are arranged in parallel layers. -Metamorphic Rocks with randomly arranged crystals are said to be non-foliated. - Used to identify a mineral s identity. -Geologist Moh developed a hardness scale starting with (1) Talc (softest) and ending with (10) Diamond (hardest). -Moh s Hardness scale allowed Geologists to see that any mineral can scratch any other mineral that is softer than itself. -One of three rock types. -The name comes from the Latin word ignis which means fire. - Igneous Rocks that form from magma beneath the Earth s surface are called intrusive igneous rocks. -Igneous rocks that form from lava above the Earth s surface are called extrusive igneous rocks. -Any feature on the Earth s surface caused by erosion, sedimentation or plate movement. - Some examples include hills, valleys, deltas, mountains or plateaus. -The process of forming a rock from sediments usually by compaction and cementation. Mechanical Weathering

3 -The process where rock is physically broken into smaller pieces. Examples of Mechanical weathering are Release of Pressure ( After erosion breaks down the surface of a rock, pressure on the rock is reduced allowing the outside surface of the rock to crack and flake.), Freezing and Thawing (Frozen water in the rock will expand the crack in a rock.), Animals (Burrowing animals loosen and break apart rocks in the soil.), Plant Growth (Roots enter and grow into a rock s crack and loosen the rock.), Abrasion (Sand and rock particles are carried by agents of erosion (wind, water and ice) and wear down the surface of existing rock.) Metamorphic Rock Minerals - A type of rock formed deep inside the Earth that changes an existing rock with tremendous amounts of heat and pressure over millions of years. - Make up rocks. -They are: 1. Naturally occurring. 2. Inorganic. 3. Solid. 4. Crystal structure. 5. Definite chemical composition. Minerals -are identified by their: 1. Color. 2. Streak (Identify the color of a mineral on a Streak Plate). 3. Luster (How the mineral reflects light). 4. Density (volume displacement in water; Mass (g)/volume (ml)). 5. Moh s Hardness Scale. 6. Crystal structure (cubic, hexagonal, tetragonal and others). 7. Cleavage and fracture. 8. Special properties (glowing, magnetism). Oxygen

4 Rock Cycle - An abundant element that is found in the atmosphere, water and rocks. -An endless cycle of rock formation and sedimentation that can veer toward many pathways. -Pathways depend on the physical processes involved (deposition, compaction, cementation/heat and pressure/melting/cooling and hardening). Sedimentary Rock Streak Weathering -One of three rock types. - They are found on or in the crust. -They can be classified as either Clastic (particles and fragments are squeezed together) or Organic (formed by remains of plants and animals) or Chemical (formed by mineral deposits left when seas or lakes evaporate -The color of a mineral in a powder form. The color does not always appear as the actual color of the mineral. -The physical (mechanical) and chemical breakdown of a mineral or rock into smaller pieces. -Processes include freezing and thawing, hot and cold temperatures, ice, wind, water and acidic and salty solutions. - Plant roots are also factors that can affect weathering. Identify physical properties of rocks. -Geologists observe and study the rock s mineral composition, color and texture (grain size). -Some rocks have large size grains and are defined as course-grained. - Igneous rocks form from the cooling of molten rock (magma or lava). -Sedimentary rocks form from the particles of other rocks, the remains of plants and animals and the formation of crystals from dissolved mineral solutions. -Metamorphic rocks form from existing rocks when extreme heat and pressure are applied over millions of years Describe the Rock Cycle.

5 -The Rock Cycle is a series of natural processes by which rocks slowly change from one kind of rock to another. -The processes include melting; weathering and erosion, deposition, compaction, cementation; cooling and hardening; heat and pressure. -The Rock Cycle can change any of the three rock types into another rock type or another rock within the same rock type family (S., I. M.). -Rocks change over time as well as the paths they take in the Rock Cycle. Explain how erosion affects the Rock Cycle. -Weathering and erosion breaks down rock particles of Sedimentary, Igneous and Metamorphic rocks that are found mostly on or in the crust. Identify silicon and oxygen as elements commonly found in minerals. -The most common mineral found on or in the crust is the family of Silicate minerals which are formed from the chemical bonding of the elements silicon and oxygen. - Glass is made from silicates. - The sand on the beach is classified as silicate minerals. Describe how Igneous rocks with a large grain size form on Earth. -Slow cooling magma form course grain (large) crystals inside the earth and are classified as Intrusive Igneous rocks. Given a table, compare the hardness of different minerals. Moh s Hardness Scale is 1-10, 1 (Talc) being the softest and 10 (Diamond) the hardest minerals. -Each mineral can scratch a mineral with a lesser number. -For example, a 2 can scratch a 1 but not a 3. Given a table, compare the density of different minerals. -A Petrologist will measure the mass (g) of the mineral and then perform a volume displacement procedure in water to determine how many ml the water rose. - Mass (g)/volume (ml) = Density of the mineral. Compare the origin and chemical composition of I. M. and S. rocks.

6 Igneous Metamorphic Sedimentary Extrusive-Formed by lava on the Crust. -Lava low in silica usually forms dark colored rocks. -Extrusive Igneous rocks have a fine-grained or glassy texture. -Rapid cooling lava forms fine grain rocks with small crystals (Exception is Volcanic glass like Obsidian which has no crystal structure.) Intrusive-formed by magma in the Crust. -Magma high in Silica usually forms light- colored rocks. -Intrusive rocks have larger crystals than Extrusive Igneous rocks. -Slow cooling magma forms course-grained rock with large crystals. Formed by Heat and Pressure beneath the Earth s surface. -Appearance, texture, crystal structure and mineral content change. -Can form out of all three rock types. -Classified by the arrangement of the grains that make up the rock. Foliated Crystals- grains arranged in parallel layers. Nonfoliated Crystals- grains are randomly arranged. -Formed from Sediments found on or in the crust. Clastic-rock fragments are squeezed together. -large and small particles. Organic plant and animal remains deposited in thick layers. Chemical- occurs when minerals in a solution dissolve and crystallize because of evaporation. Identify the processes responsible for the formation of sedimentary rocks. -Weathering (physical, mechanical and chemical) and erosion; deposition; compaction; cementation. Recognize examples of landform change caused by water and wave action.

7 -Examples include river deposits (As water moves it carries sediment with it. Deposition in the river bed can create alluvial fans (formed where a stream flows out of a steep, narrow mountain valley.), deltas (Located where a river enters a larger body of water. Sediment that drops to the bottom of the river can build up forming a delta.) and adding soil to the river s flood plain (Deposition can occur during flooding creating a fertile valley around the river.). Explain how resistance to erosion determines landforms. -Factors that create less erosion are the amount of rain an area receives, vegetation, the type of soil, shape and slope of the landform