III. Water Underground A. Loca2on of under ground water h6ps://youtu.be/oNWAerr_xEE 1.  Zone of aera2on= upper zone where rainwater passes through 2.  Zone of satura2on= beneath the zone of aera2on where the spaces between the rock par2cles are filled with water 3.  Water table= Boundary between the 2 zones B. Aquifers: rock layer that stores water underground & allows the flow of that groundwater 1.  Porosity: percentage of open space between individual rock par2cle in a rock layer h6ps://youtu.be/XXFsS94HF08 –  The more open spaces in the aquifer –  Influenced by the different size par2cles in the rock layer-­‐ less smaller rocks means more space for water –  High porosity= few small rocks 2.  Permeability= rock’s ability to let water pass through a.  Impermeable= rock that stops the flow of water b.  Larger the par2cles the more permeable the rock layer-­‐ less surface area less fric2on 3.  Best aquifers form from permeable materials –  Sandstone –  limestone –  layers of sand & gravel 4.  Recharge zones= ground surface where water enters an aquifer –  Size depends on the permeability of the rock at the surface C. Springs & Wells 1.  Spring= water table underground reaches the Earth’s surface & flows out –  Important source of drinking water –  Lakes form when the water table is higher than the Earth’s surface 2.  Artesian Springs= a spring whose water flows from a crack in the cap rock over the aquifer –  Artesian forma2on= a sloping layer of permeable rock sandwiched between two layers of impermeable rock –  Top layer of impermeable rock is the cap rock –  Most are cool water –  Hot springs form when the water goes deep into the Earth= up to 50 oC or 122o F h6ps://youtu.be/KMtEQqbi4CI h6ps://youtu.be/9GZAAdOBaOo 3.  Well= Human-­‐made hole that is deeper that the level of the water table –  Must be deep enough to reach the aquifer –  Water must not be drawn out too fast or it will go dry h6ps://youtu.be8K6V450StO4 D. Underground erosion & deposi2on 1.  Water can erode rock underground –  Limestone erodes more easily 2.  Caves can form from underground erosion –  Water that drips from a crack in a cave’s ceiling leaves deposits of calcium carbonate •
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Stalac2tes: “hang 2ght” like icicles from the ceiling Stalagmites form when the water allows the minerals to form a column up from the floor (down by the mice) h6ps://youtu.be/UvxOy-­‐6BWrs •
h6ps://youtu.be/6pha_shqeL8 3.  Sinkholes= when the water table is lower that the level of a cave & the roof of a cave collapses leaving a circular depression –  Can form lakes where the water table is high