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FRESHWATER CORNELL NOTES

FRESHWATER CORNELL NOTES. R. Michelle Esserwein Palmer Middle School 6 th Grade AC Science. Distribution of Water. Earth stands out from other planets in our solar system primarily for one reason----WATER!!! 71% of Earth’s surface is covered with water 97% Salt Water 3% Freshwater Ice

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FRESHWATER CORNELL NOTES

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  1. FRESHWATER CORNELL NOTES R. Michelle Esserwein Palmer Middle School 6th Grade AC Science

  2. Distribution of Water • Earth stands out from other planets in our solar system primarily for one reason----WATER!!! • 71% of Earth’s surface is covered with water • 97% Salt Water • 3% Freshwater • Ice • Shallow groundwater • Deep groundwater • Lakes/Rivers • Water Vapor

  3. Groundwater • Water located within the rocks below Earth’s surface. • Important resource • Plays an important role in erosion & deposition.

  4. Underground Layers

  5. Location of Groundwater • Surface water seeps underground into the soil & rock. • Underground area divided into two zones: • Zone of aeration • Zone of saturation • Two zones meet at a boundary known as the water table.

  6. Zone of Aeration • The area above the water table is the zone of aeration. • This permeable layer allows the water to infiltrate down to the water table. • Also called “unsaturated zone”.

  7. Zone of Saturation • When water reaches an impermeable layer, it cannot soak in any deeper. • The spaces between the rock particles are filled with water. • If you dig a hole this deep you will see your hole start to fill with water. • Saturated means to soak or fill completely.

  8. Water Table • The top of the saturated zone is called the water table. • The more it rains, the higher the water table will get. • The more water you take out through a well, the lower the water table will get. • Knowing the depth of the water table will tell you how far down you must dig to find water. • Where the water table is above ground you will find streams, ponds, and lakes.

  9. Aquifers • A body of rock or sediment that stores groundwater and allows the flow of groundwater. • Usually form in permeable materials: sandstone, limestone, layers of sand/gravel. • Some cover large, underground areas. • Important water source for cities and agriculture

  10. Porosity • Percentage of the total volume of a rock or sediment that consists of open spaces. • More open spaces/pores = more water it can hold (i.e. an aquifer) • Influenced by differences in sizes of particles in the rock layer. • Layer w/many particles of different sizes = low porosity as small particles will fill up empty spaces. • Layer w/many same-sized particles=high porosity as there is more open space between the particles.

  11. Permeability • Ability of a rock or sediment to let fluids pass through its open spaces or pores. • The larger the particles, the more permeable rock layer. • Sand and gravel will have large pores between the grains, so they are very permeable.

  12. Impermeable • Does not allow water to easily pass through. • Has few pores or cracks. • Will cause water to pool on top of it. • Clay and granite are impermeable.

  13. Recharge Zone • Aquifers need a constant supply of water to maintain the water table via the water cycle. • The ground surface where water enters an aquifer is called the recharge zone. • Size depends on how permeable the rock is at the surface. • Aquifer covered by an impermeable rock layer, water cannot reach it. • Construction of buildings on top of the recharge zone also limits the amount of water that enters an aquifer.

  14. Bringing Groundwater to the Surface

  15. Springs • If the water table is at ground level, water may flow out of the ground. • This is called a spring. • Usually occur on sides of hills or in low areas. • Important source of drinking water.

  16. Artesian Springs • Artesian formation: Sloping layer of permeable rock sandwiched between two layers of impermeable rock. • Permeable rock = aquifer • Top layer of impermeable rock = cap rock • Artesian spring: Spring whose water flows from a crack in the cap rock of the aquifer. • Often found in deserts.

  17. Wells • A human made hole that extends down past the water table. • Water must be pulled or pumped up to be used. • Dries up when water table falls below the bottom of the well.

  18. Underground Erosion & Deposition • Groundwater causes erosion by dissolving rock. • Contains weak acids (carbonic acid); dissolves rock • Types of rock (limestone) dissolves in groundwater easily. • Underground erosion forms caves. • Caves are also a sign of deposition. • Water drips from a crack in the cave’s ceiling leaving deposits of calcium carbonate. • Stalactites=Sharp, icicle-shaped features; form on cave ceilings. • Stalagmites=Cone-shaped features; form on the floor of a cave from water falling from above. • Dripstone column=Stalactites and stalagmites form together.

  19. Underground Erosion & Deposition (continued) • When the water table is lower than the level of a cave, the case is no longer supported by the water underneath. • Roof of cave collapses, leaving a circular depression called a “sinkhole”. • Often form lakes in areas where the water table is high. • Example: Central Florida is covered with hundreds of round sinkhole lakes.

  20. Sinkhole in Winter Park, Florida

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