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Presentation on theme: "ns/lessons/Metrocks/Metrocks2.html."— Presentation transcript:














14 ns/lessons/Metrocks/Metrocks2.html

15 Categories of Igneous Rocks: – Intrusive Formed inside Earth Found when volcano erupts and are pushed out or through mining Contain large mineral grains – Extrusive Form outside surface Lava cools quickly Rocks generally contain holes; gas escapes

16 Pumice is lava that had a lot of gases in it and cooled quickly on the surface of the Earth. Granite: Igneous, Intrusive Obsidian - volcanic glass that is formed by very rapid cooling of lava

17 Earths Relation – They can form from tectonic processes such as continental collisions. – They are also formed when rock is heated up by the intrusion of hot magma from the Earth's interior. – Metamorphic rocks become exposed at the Earth's surface by erosion and uplift. – Studying metamorphic rocks tells us about the temperatures and pressures that occur at great depths within the Earth's crust.


19 Ways sedimentary rocks form: – Compaction Sediments are pressed together. – Cementation Sediments are glued together. – Deposition of minerals Minerals in solution are left when water evaporates.

20 Fossillferous Limestone contains fossils of various fresh and or salt water shell fish. Breccia composed of sharp angled fragments Rock Salt: This is an evaporate after the water evaporated from saltwater.





25 Superposition refers to, placing on top of each other. Scientists use the Law of Superposition to determine whether a fossil or a layer of rock is older or younger than another fossil or layer of rock. This law states that in a series of sedimentary rock layers, younger rocks normally lie on top of older rocks.

26 Scientist use the decay of radioactive elements to determine the age of rocks. Radiometric dating indicates that the Earth is about billion years old Radioactive Decay: – Unstable elements that breakdown, or decay, by releasing particles and energy in the process and form another element Carbon – 14 – Used to find the absolute age of rocks – Carbon-14 has a half-life of 5730 years. – It is only useful for dating materials that contain Carbon and lived no more than 50,000 years ago.




30 Complex internal processes such as plate tectonics and mountain-building have formed these rocks and brought them to the Earth's surface. Earthquakes are the result of the sudden movement of crustal plates, releasing internal energy that becomes destructive at the surface. Internal heat and energy are released also through volcanic eruptions. External processes such as glaciation, running water, weathering, and erosion have formed the landscapes we see today ,articleId-9456.html

31 1.Evidence located at PLATE BOUNDARIES 2.Evidence left behind from WEATHERING 3.Evidence left behind from EROSION AND DEPOSITION EXAMPLES of EVIDENCE 1.Himalayas, Andes, Hawaiian Islands – all found at different plate boundaries. 2.Stalactites and stalagmites are the remains of rocks which went through chemical weathering. 3.Gullys, deltas, valleys, sand dunes, landslides are created through time as a result of moving water, ice, wind, and gravity.

32 1.Evidence from LANDFORMS - PANGEA 2.Evidence of FOSSILS 3.Evidence from CLIMATE EXAMPLES of EVIDENCE 1.Mountain ranges in Africa line up with those in South America. 2.Fossils of the plant Glossopteris found in rocks on widely separated landmasses 3.Fossils of tropical plants found near Arctic Circle





37 Proposed a theory stating that in the distant past, the Earths continents were all joined as a single landmass. When Wegener placed all the continents together like a puzzle, it formed a large landmass which he called Pangaea. Wegener stated that this supercontinent began to break up about 200 million years ago.














51 Folded mountains are formed by crust which have been uplifted and folded by compressional forces. These mountains occur along convergent plate boundaries either between continental plates or between an oceanic and a continental plate. Examples: – Rockies – Andes – Alps – Himalayas FAULT-BLOCK Mountains These mountains form when faults or cracks in the Earth's crust force some materials or blocks of rock up and others down. Instead of the Earth folding over, the blocks are stacked. Examples: – Sierra Nevada Mts. – Harz Mts.

52 Volcanoes form when material from inside the Earth reaches the surface. – Magma: Molten rock found inside the Earth – Lava: Molten rock when outside surface is reached Volcanoes are most commonly found at both convergent and divergent plate boundaries. A major belt of volcanoes is the Ring of Fire which encircles the Pacific Ocean. WHY THEY EXPLODE Temperatures in the mantle are hot enough to melt rock into magma. Since magma is less dense than the solid rock around it, magma rises and some of it collects in magma chambers. As the magma rises, pressure decreases allowing trapped gasses to expand and propel the magma through openings in the Earths surface causing an eruption.


54 Mt. Etna, Italy Shield Volcano 1943 Eruption of Paricutin – Mexico Cinder cone Volcano Mt. St. Helens, 1982 Composite Volcano

55 LANDAIRWATER LavaPoisonous gassesHot Springs Volcanic AshAcid RainGeysers LandslidesHazeDeep Sea Vents MudflowsLower TempsFumaroles



58 Location where the earthquake energy is released inside the Earth. At the focus, seismic waves are produced and sent out. – What we feel SEISMIC WAVES 1.Primary Waves (P Waves) – Travel through rocks – Take a straight path – Move the fastest 2.Secondary Waves (S Waves) – Causes rocks to vibrate – Takes a straight path – Rocks move up/down 3.Surface Waves – Move above ground – Move up/down and side/side – Causes destruction – Travels the slowest

59 The damage from earthquake waves depends on several factors. –Intensity and duration of the vibrations –The nature of the material on which the structure is built –The design of the structure OTHER DANGERS Tsunami –The ocean floor moves vertically along a fault. –The vibration of a quake sets an underwater landslide into motion. Landslides –The greatest damage to structures is from landslides and ground subsidence. –The sinking of the ground can also be triggered by vibrations.




63 Pollution is the harmful alteration of our environment by our own actions. People depend on biological diversity for the quality of their lives. TYPES of POLLUTION Air Pollution – Caused by the burning of fossil fuels Water Pollution – Sewage, chemicals, etc. Land Pollution – Pesticides, herbicides, garbage Global Warming – Ozone depletion

64 Vegetation is a source of food, building material, fuel, and medicine. Destruction of vegetation: – Fire clearance of vegetation, soil erosion, flooding, and wind erosion – Deforestation Ecosystems, nutrient cycles are affected as well as a loss of biodiversity SOIL Soil is unique in that it depends on plants and vegetation for its existence, yet plants depend on soil for their support, air, water, and nutrients. Destruction of soil: – Soil compaction Prevents plant growth and encourages erosion – Erosion of soil Increases flooding, landslides, and increases sediment loads leading to silting up of reservoirs

65 The ocean has the greatest biodiversity anywhere on the planet. Destruction of oceans and its contents: – Over fishing The depletion of fish in one area can cause the destruction of marine ecosystems. – Water pollution Caused by untreated sewage, oil, industrial chemicals, and radioactive waste LANDSCAPE Over the past century, humans have radically altered the face of the Earth. Destruction of land: – Mining Pulling out natural resources Dumping of waste – Building Causes loss of habitat by harvesting natural resources - Urbanization

66 Sources of air pollution are volcanoes, factories, and cars (both human and natural activities). Destruction of Air Quality: – Greenhouse Effect When fossils fuels are burned, excess carbon dioxide is created resulting in the depletion of the ozone layer – Global Warming WATER QUALITY Surface and groundwater contamination come greatly from factories, homes and farms. Destruction of Water Quality: – Water Contamination Fertilizers, insecticides, and fluids from cars run off into ponds, rivers, and streams contaminating them. Some of this polluted water seeps into the ground contaminating our drinking water.



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