Transcript Water
Review: Weathering and Erosion What is Mechanical Weathering? What is Mechanical Weathering? • When physical forces break rock into smaller pieces • Does not change the rock’s composition • Three Ways – Frost Wedging – Unloading – Biological Activity Mechanical Weathering: _________________? Mechanical Weathering: Frost Wedging • Water enters cracks and crevices in rocks • Water freezes expanding the cracks • Eventually breaking rock into pieces Mechanical Weathering: _________________? • The uplift and weathering of rocks overlying igneous rocks • Why? – Pressure on igneous rocks is reduced causing uplift • ____________?: slabs of outer rock separate and break loose Mechanical Weathering: Unloading • The uplift and weathering of rocks overlying igneous rocks • Why? – Pressure on igneous rocks is reduced causing uplift • Exfoliation: slabs of outer rock separate and break loose Mechanical Weathering: _________________? • Activities of living organisms • Example: –Plant roots wedge into rocks, breaking them apart What is Chemical Weathering? What is Chemical Weathering? • Is the transfer of rock into one or more new compounds Agents of Chemical Weathering • _________? – Most important agent – Picks up gases from the atmosphere • _________? – Causes oxidation of metal minerals – Ex: rusting • _________? – Carbon dioxide from respiration, sulfur dioxide and nitrogen oxides from burning fossil fuels – Combines with water in the atmosphere to form acids like in acid rain Agents of Chemical Weathering • Water – Most important agent – Picks up gases from the atmosphere • Oxygen – Causes oxidation of metal minerals – Ex: rusting • Emissions – Carbon dioxide from respiration, sulfur dioxide and nitrogen oxides from burning fossil fuels – Combines with water in the atmosphere to form acids like in acid rain Rate of Weathering What affects it? Rate of Weathering What affects it? • Rock Characteristics – Mineral composition – Mineral solubility • Climate – Temperature and moisture – Favors high temperatures and abundant moisture • Surface area • Topography (slope/gravity) How is Soil Formed? How is Soil Formed? • Weathering of rocks that is carried away • Factors – Parent Material – Time – Climate – Organisms – Slope Soil Texture Triangle Percent Percent Percent Texture Clay Silt Sand Type 60 20 20 20 40 40 10 20 70 What is Erosion? What is Erosion? • Removal and transport of weathered material from one location to another Agents of Erosion? Agents of Erosion • • • • Running Water Wind Glaciers Ocean currents and Waves • Biological Organisms What happens to the Material? • _________? –Materials are dropped in another location –Final stage of erosion What happens to the Material? • Deposition –Materials are dropped in another location –Final stage of erosion What is a Glacier? What is a Glacier? • Large, moving mass of ice that forms near Earth’s poles and in mountainous regions at high elevations How do Glaciers Erode Soil? How do Glaciers Erode Soil? • Scrape and gouge out large sections of landscape • Can carry huge rocks and piles of debris over great distance How can humans control erosion? How can humans control erosion? • Planting rows of trees called windbreakers • Terracing hillsides • Plowing along the contours of hills • Rotating crops What is Mass Movement? What is Mass Movement? • The transfer of rock and soil down-slope due to gravity Triggers of Mass Movement Triggers of Mass Movement • Water – Heavy rain and rapid snow melting saturate the surface – Particles slide past one another easier • Over-steepened Slopes – The steeper the slope, the greater the chance for movement • Removal of Vegetation – Roots keep soil intact – Removing plants increase chances of movement and erosion • Earthquakes – Dislodge rocks and minerals How to Classify Mass Movement? • Classified by: How to Classify Mass Movement? • Classified by – Kind of material moved – How it moves – Speed of movement Types of Mass Movement Types of Mass Movement • Rock falls • Slides – Rockslides – Landslides • Slumps • Flows – Mudflow – Earthflow • Avalanches • Creep Preventative Actions Preventative Actions • Dig series of trenches to divert running water • Constructing protective fences on highways • Retaining walls for weak slopes • Don’t build on steep slopes The Hydrosphere Distribution of Water On Earth Distribution of Water On Earth • 71% of Earth is water – 97% in the oceans – 3% is freshwater • 2% in ice and glaciers • 0.6% in underground water • 0.4% in rivers, streams, lake and atmosphere Parts of the Water Cycle A. __________? liquid water changes into water vapor B. __________? liquid or solid water from the clouds C. __________? water vapor that turns into liquid making clouds D. __________? liquid water moving through the ground E. __________? water vapor released to the air by plants F. _______? when liquid hit the ground but not absorbed Parts of the Water Cycle A. Evaporation: liquid water changes into water vapor B. Precipitation: liquid or solid water from the clouds C. Condensation: water vapor that turns into liquid making clouds D. Infiltration: liquid water moving through the ground E. Transpiration: water vapor released to the air by plants F. Runoff: when liquid hit the ground but not absorbed The Water Cycle How is Water Used? • 70% in ______? • 20% in ______? • 10% in ______? How is Water Used? • 70% in Irrigation • 20% in Industries • 10% in Cities and Residences How do Currents Influence Climate? How do Currents Influence Climate? • Exchanges heat in the water with the atmosphere • Type of current nearby influences weather for an area – Warm currents bring warm temperatures – Cold currents bring cooler temperatures Current Movement • Warm Currents: ________________ • Cold Currents: ________________ Current Movement • Warm Currents – Move from the tropics to the poles – Ex: Gulf Stream (east coast of the US) • Cold Currents – Move from the poles to the equators – Ex: Canary Current Why do Current Moves? • Primary Forces? • Secondary Forces? Why do Current Moves? • Primary Forces – Start the movement – Solar heating, winds, gravity, Coriolis • Secondary Forces – Influences where the current flows How does water become Groundwater? • _____________? – How easily water can pass through connected pore spaces • ___________? – Percentage of pore spaces in soil and rock – Clay has the smallest percentage (not permeable) How does water become Groundwater? • Permeability – How easily water can pass through connected pore spaces • Porosity – Percentage of pore spaces in soil and rock – Clay has the smallest percentage (not permeable) Groundwater Layers A. ________________? – Area above the water table where water passes through B. ________________? – Area where the soil, sediment and rock are saturated with water C. ________________? – The upper level of the zone of saturation D. _______________? – The water within the zone of saturation Groundwater Layers A. Zone of Aeration – Area above the water table where water passes through B. Zone of Saturation – Area where the soil, sediment and rock are saturated with water C. The Water Table – The upper level of the zone of saturation D. Groundwater – The water within the zone of saturation Aquifers Aquifers • Underground layer of water bearing permeable rock (gravel, sand or silt) from which ground water can be extracted using a well Wells • A hole bored into the zone of saturation • Pumping can cause the water table to be lowered • Artesian Well? Wells • A hole bored into the zone of saturation • Pumping can cause the water table to be lowered • Artesian Well – Groundwater rises on its own under pressure Problems with Groundwater? Problems with Groundwater • Withdrawing water for agriculture • Toxic metals contaminating the water (arsenic, cadmium, lead) • Salt water intrusion – Salt water from the ocean enters the groundwater near coastal areas A Stream’s Profile A. ___________? – – At the beginning of a stream Usually at the mountains or higher elevations B. __________? – – At the end of a stream Usually at the ocean or another water body C. _________? – A stream that empties into another stream A Stream’s Profile A. Headwater – – At the beginning of a stream Usually at the mountains or higher elevations B. Mouth – – At the end of a stream Usually at the ocean or another water body C. Tributary – A stream that empties into another stream Watershed? Watershed • An area of land that contains a common set of streams and rivers Drainage Basins? Drainage Basins • Is the land area that contributes water to a stream Results of Floods • _____________? – Area where water floods the land • Provides a supplement of nutrient-rich silt to floodplain areas • Recharges groundwater • Kills and causes property damages Results of Floods • Floodplain – Area where water floods the land • Provides a supplement of nutrient-rich silt to floodplain areas • Recharges groundwater • Kills and causes property damages How to control Floods? • _______________? – Concrete or Earthen mounds built on the banks of a river – Increases the amount of water it can hold • _______________? – Parallels a stream and helps to contain its water, except during flood stage How to control Floods? • Artificial Levees – Concrete or Earthen mounds built on the banks of a river – Increases the amount of water it can hold • Natural Levees – Parallels a stream and helps to contain its water, except during flood stage • ____________? – Stores floodwater and lets it out slowly • ____________? – Preserve floodplains instead of building on them • Flood-Control Dams – Stores floodwater and lets it out slowly • Limit Development – Preserve floodplains instead of building on them Human Activities Causing Flooding • • • • • • • • Removing vegetation Overgrazing Mining Building on floodplains Logging Forest fire Destruction of wetlands Urbanization Human Activities Causing Flooding • • • • • • • • Removing vegetation Overgrazing Mining Building on floodplains Logging Forest fire Destruction of wetlands Urbanization Types of Water Pollution • __________________? – Organic waste and manure • _______________? – Acids, arsenic, lead • ________________? – Nitrogen and phosphorus • ________________? – Oil, detergents, pesticides • _______________? – Erosion and soil Types of Water Pollution • Oxygen Demanding Agents – Organic waste and manure • Toxic Metals – Acids, arsenic, lead • Inorganic Plant Nutrients – Nitrogen and phosphorus • Organic Chemicals – Oil, detergents, pesticides • Sediment – Erosion and soil Oxygen Demanding Agents • __________? is removed from water by bacteria (B.O.D) • Fish can’t live in streams without _________? Oxygen Demanding Agents • Oxygen is removed from water by bacteria (B.O.D) • Fish can’t live in streams without oxygen _______________? • #1 source of water pollution • Clouds the water • Blocks sunlight for the aquatic plants Sediment • #1 source of water pollution • Clouds the water • Blocks sunlight for the aquatic plants Protecting The Water • __________________? – Regulates the discharge of pollutants in the US river and streams • __________________? – Protect the quality of drinking water – Water treatment plants – Well water Protecting The Water • Clean Water Act (1972) – Regulates the discharge of pollutants in the US river and streams • Safe Drinking Water Act (1974) – Protect the quality of drinking water – Water treatment plants – Well water Water Conservation Methods Water Conservation Methods • Repair leaking faucets and pipes • Landscape using plants requiring little water • Use drip irrigation • Use water saving appliances • Purify and reuse water