Geology Facts

1. Geology Facts

2. SOL 4 The student will investigate and understand how to identify major rock forming and ore minerals based on physical and chemical properties. Key concepts include: hardness, color and streak, luster, cleavage, fracture, and unique properties; and uses of minerals. • Essential Questions • How do properties of minerals and rocks affect their classification and use? • How does the rock cycle explain the process of the transformation of rocks over time? • How does the geology and mineralogy of Virginia affect its economy?

3. What you must know • A mineral is a naturally occurring, inorganic, solid substance with a definite chemical composition and structure. • Minerals may be identified by their physical properties such as hardness, color, luster, and streak. • Some major rock-forming minerals are quartz, feldspar, calcite, and mica. • Ore minerals include pyrite, magnetite, hematite, galena, graphite, and sulfur. • The major elements found in Earth’s crust are oxygen, silicon, aluminum, and iron. • The most abundant group of minerals is the silicates, which contain Si and O • Minerals are important to human wealth and welfare. Important minerals and ores and their uses are summarized in this table (for student awareness only). • Name of mineral/ore Use(s) • Quartz (mineral) Glass, watches • Feldspar (mineral) Toothpaste • Calcite (mineral) Neutralizing acids • Mica (mineral) Lampshades, insulation • Pyrite (ore) Iron ore • Magnetite (ore) Iron ore • Hematite (ore) Iron ore • Galena (ore) Lead • Graphite (ore) Lubricant • Sulfur (ore) Rubber, medicines • Bauxite (ore) Aluminum

4. Minerals • A mineral is found in nature, inorganic, solid, with a definite chemical composition and structure. (crystalline)

5. Mineral properties depend on their atomic structure

6. Ores are useful and profitable • Ores of Common Metals Contains: bauxite, bornite, chalcopyrite, chalcocite, pit ore, magnetite, hematite, specular hematite, galena, pyrolusite, garnierite, sphalerite, chromite, stibnite, and molybdenite.

7. Minerals are determined by their streak, cleavage, fracture, hardness, color, luster, and special properties • Streak- The color of the mineral in powder form. This test is done by rubbing the mineral across a white streak plate. Several minerals have a streak that is not the same color as the mineral itself. Most metallic luster minerals have a dark colored streak

8. Cleavage and Fracture • Cleavage or Fracture- If a mineral breaks along flat, smooth surfaces it shows cleavage. Cleavage can be in one, two or three directions. Some examples are: • Mica- cleavage in one direction, see the diagram below (upper right), • Feldspar- cleavage in two directions, see the diargam below (lower left), • Calcite, Galena and Halite- cleavage in three directions, see the diargam below (lower right). • If a mineral breaks along irregular rough surfaces it shows fracture. Quartz shows a special type of fracture called concoidal (shell-like) fracture.

9. Hardness • Hardness- The ability of one mineral to scratch another. The softer mineral gets scratched. You test a mineral's hardness by scratching the unknown mineral with an object of known hardness. Moh's Scale of Hardness is used to rate the hardness of a mineral. The chart below shows the ten minerals that make up the hardness scale and some common materials with their hardness to test unknown minerals. One on the scale is the softest and ten is the hardest. • To find the hardness of a mineral you first have to find out what it can scratch and what can scratch it. For example, if a mineral can scratch glass but can't scratch a streak plate, the mineral has a hardness of 6 on the Moh's Hardness Scale.

10. Color • Color- The most easily observed property, but usually the least useful. A mineral's color can be changed by the impurities that are found in the mineral.

11. Luster • Luster- The way light is reflected from a newly exposed surface. Described as either metallic or nonmetallic. Some examples of minerals with metallic luster are pyrite, galena and magnetite. Some examples of minerals with nonmetallic luster are calcite, quartz and feldspar. Nonmetallic luster can also be described as glassy, pearly, waxy and earthy (dull).

12. Special Properties • Acid test- This test is performed by dropping weak hydrochloric acid on the mineral. If it reacts (fizzes) then the mineral is calcite. This test will also help to identify the rocks limestone and marble, because calcite is the principal mineral in both. • Magnet test- If there is a magnetic attraction between your mineral and a metal object, then the mineral has a high iron content. The mineral magnetite will attract metal objects.

13. SOL 5 The student will investigate and understand the rock cycle as it relates to the origin and transformation of rock types and how to identify common rock types based on mineral composition and textures. Key concepts include: igneous rocks; sedimentary rocks; and metamorphic rocks. Essential Questions What is the difference between igneous, sedimentary, and Metamorphic rocks? How do igneous rocks form? What are the characteristics of igneous rocks? How do sedimentary rocks form? What are the characteristics of Sedimentary rocks? How do metamorphic rocks form? What are the characteristics of metamorphic rocks? What is the rock cycle?

14. What you have to know • Most rocks are made of one or more minerals. • Igneous rock forms from molten rock that cools and hardens either below or on Earth’s surface. • Extrusive igneous rocks have small or no crystals resulting in fine-grained or glassy textures. • Intrusive igneous rocks have larger crystals and a courser texture. • Extrusive igneous rocks include pumice, obsidian, and basalt. • Intrusive igneous rocks include granite. • Sedimentary rocks may either form from rock fragments or organic matter bound together or they are formed by chemical precipitation. • Sedimentary rocks are clastic or chemical. • Clastic sedimentary rocks are made up of fragments of other rocks and include sandstone, conglomerate, and shale. • Non-clastic sedimentary rocks include limestone and rock salt. • Metamorphic rocks form when any rock is changed by the effects of heat, pressure, or chemical action. • Metamorphic rocks can be foliated or unfoliated (non-foliated). • Foliated metamorphic rocks have bands of different minerals. Slate, schist, and gneiss are foliated metamorphic rocks. • Unfoliated metamorphic rocks have little or no banding and are relatively homogeneous throughout. Marble and quartzite are unfoliated metamorphic rocks.

15. Igneous Rocks Igneous rocks are classified by their composition and texture

16. Igneous rocks are produced by the cooling of magma or lava. • Fast cooling = extrusive, small crystals. Slow cooling = intrusive, larger crystals

17. Extrusive small grains, glassy, air holes present (obsidian, pumice, basalt)

18. Intrusive large grained, granite

19. Metamorphic formed by heat and pressure

20. Metamorphic classified as foliated (banded) or non foliated • Foliated rocks are slate, schist, gneiss • Non-foliated include marble and quartzite

21. Limestone morphs into marble. Sandstone morphs into quartzite

22. Sedimentary • Sedimentary rocks are formed from rock fragments, organic material, or chemical precipitation • Sedimentary are classified as clastic, organic, and chemical

23. Clastic rocks are made of fragments –conglomerate, sandstone, shale

24. Limestone is formed both chemically and organically • Sedimentary are found in flat layers or strata. Fossils are found in these layers

25. Essential questions What are the resources found in Virginia? What is the difference between renewable and nonrenewable resources? • SOL 6 The student will investigate and understand the differences between • renewable and nonrenewable resources. • Key concepts include: • fossil fuels, minerals, rocks, water, and vegetation; • advantages and disadvantages of various energy sources; • resources found in Virginia; and • environmental costs and benefits.

26. What you have to know • In Virginia, major rock and mineral resources include coal for energy, gravel and crushed stone for road construction, and limestone for making concrete. • Important rocks and their uses are summarized in this table. • Name of rock Use(s) • Coal (sedimentary) Energy • Gravel/crushed stone (all) Road construction • Limestone (sedimentary) Concrete • Granite (igneous) Building materials • Pumice (igneous) Lava soap abrasion • Quartzite (metamorphic) Building materials • Slate (metamorphic) Roofing, pool tables • Nonrenewable energy resources include fossil fuels and minerals. • Renewable resources include vegetation, sunlight and surface water.

27. Virginia resources include limestone, coal and gravel

28. Renewable resources can be replaced by nature at a rate at which they are used. Includes vegetation, water, and soil

29. Nonrenewable resources are renewed very slowly or not at all. Includes coal, oil, and minerals

30. Essential questions How do weathering, erosion, and deposition (sedimentation) affect the surface of the Earth? How does Earth’s water supply change? Why is the conservation of soil important? • SOL 8 The student will investigate and • understand how freshwater resources are influenced by geologic processes and the activities of humans. Key concepts include: processes of soil development; • development of karst topography; • relationships between groundwater zones, including saturated and unsaturated zones, and the water table; • identification of sources of fresh water including rivers, springs, and aquifers, with reference to the hydrologic cycle; • dependence on freshwater resources and the effects of human usage on water quality; and identification of the major watershed systems in Virginia, including the Chesapeake Bay and its tributaries.

31. What you have to know • Factors – speed, volume, slope influence cutting ability – meanders. • Weathering is the process by which rocks are broken down chemically and physically by the action of water, air, and organisms. • Erosion is the process by which Earth materials are transported by moving water, ice, or wind. • Deposition is the process by which Earth materials carried by wind, water, or ice settle out and are deposited. • Weathering, erosion, and deposition are interrelated processes. • Weathering accelerates erosion and thus increases the rate of deposition. • The potential for erosion is greatest in areas of high relief. • The potential for deposition is greatest in areas of low relief, especially in standing water and in the ocean. • Permeability is a measure of the ability of a rock or sediment to transmit water or other liquids. • A substantial amount of water is stored in permeable soil and rock underground. • Water does not pass through impermeable materials. • Geological processes, such as erosion and human activities (such as waste disposal), can pollute water supplies. • The three major regional watershed systems in Virginia lead to the Chesapeake Bay, the North Carolina Sounds, and the Gulf of Mexico. • Karst topography is developed in areas underlain by carbonate rocks, including limestone and dolomite. • Where limestone is abundant in the Valley and Ridge province of Virginia, karst topography is common. • Karst topography forms when limestone is slowly dissolved away by slightly acidic groundwater. •  Karst topography includes features like caves and sinkholes.

32. Soil is formed from the weathering of rocks and organic activity. • Soil is loose rock fragments and clay derived from weathered rock mixed with organic material. • Running water is the major cause of erosion. • Down slope movement of Earth materials is caused by gravity. • Features of erosion and deposition caused by waves include deltas, beaches, and sandbars. • Features of erosion and deposition caused by glaciers include U-shaped valleys, lakes, and moraine. • Features of erosion and deposition caused by wind include blowouts, dunes and loess. • Virginia’s Coastal plain consists of young unconsolidated sediments eroded from the western higher elevations. • Virginia’s coast line is shaped by the action of waves. • The composition and structure of soil are dependent on the resources, topography and climate. • Renewable resources can be replaced by nature at a rate close to the rate at which they are used. Water is a renewable resource. • Explain the types of deposition specific to streams and rivers (such as alluvial fans and deltas).

33. Destructive Geology • Chemical weathering occurs mainly in warm, humid climates

34. Weathering can occur as either a mechanical or chemical process

35. Erosion is the process of materials being transported by moving water, ice, wind, or gravity

36. Streams and moving water are the major agents of erosion

37. Deposition is the dropping or settling out of sediments

38. High erosion= high relief areas, high deposition= low relief areas

39. Large particles settle out first, sediment size from largest to smallest- sand, silt, clay

40. As particle size increases, permeability increases (ability to hold water). • Permeability is the ability of a material to drain

41. Porosity is the amount of pore space in a rock or sediment • Different grain sizes and packing arrangements result in different porosity values.  Top: individual pore spaces decrease in size with decreasing grain size. Bottom: porosity varies with packing (arrangement) of grains.

42. Soil evolution starts with the weathering of bedrock Organic material must be present in order to have soil. (humus)

43. Soil profiles consist of 3 horizons: O topsoil (humus) most evolved, A less humus, leaching of minerals from A, and B weathered rock C These layers are on top of bedrock

44. Groundwater layers from the surface down would include zone of aeration, water table, and zone of saturation

45. An aquifer is a layer of rock that transports groundwater freely • A spring is an area where the water table reaches land’s surface

46. The Earth’s water supply is renewable but also finite

47. Karst topography has caves and sinkholes produced by acidic groundwater dissolving limestone

48. The watersheds of Virginia are the Sounds of North Carolina, the Chesapeake Bay, and the Atlantic Ocean.

50. Essential questions What is the Theory of Plate TectonicsWhat are the 3 types of plate movements? What are the stresses and faults associated with each type of plate movement? What moves the plates around the world? What is the Ring of Fire? Why are earthquakes associated with plate movement? What are the 3 types of waves? How many recording stations must receive the waves from a n earthquake to determine the Epicenter? What are the 3 kinds of volcanoes? What are the kinds of volcanoes associated with plate movement? • SOL 7 The student will investigate and understand geologic processes including plate tectonics. Key concepts include: • geologic processes and their resulting features; • SOL 10 The student will investigate and understand that oceans are complex, interactive physical, chemical, and biological systems and are subject to long- and short-term variations. Key concepts include: • d) features of the sea floor as reflections of tectonic processes.