GROUNDWATER SES3d. Relate the past and present actions of ice, wind, and water to landform distribution and landscape evolution. SES3e. Explain the processes that transport and deposit material in terrestrial and marine sedimentary basins, which result, over time, in sedimentary rock.

OBJECTIVES Describe how water moves under the Earth’s surface. Explain how groundwater dissolves and deposits rocks and minerals. Describe how the features of karst topography shape the landscape. Explain how groundwater is withdrawn from aquifers by wells.

KEY TERMS Porosity: amount of pore space in a material Zone of Saturation: region below the Earth’s surface where all the pores of a material are filled with groundwater Water Table: upper boundary of the zone of saturation Permeability: ability of a material to let water pass through Aquiclude: impermeable layer that is a barrier to groundwater Spring: natural discharge of groundwater at the Earth’s surface where an aquifer and aquiclude come in contact

KEY TERMS Hot Spring: spring that is heated to warmer than human body temperature Geyser: explosively hot springs where water is heated past its boiling point, causing it to vaporize Cave: a natural underground opening with a connection to the Earth’s surface Sinkhole: depression in the ground caused by a cave collapse or direct dissolution of limestone by acidic water Karst Topography: limestone regions with sinkholes and disappearing streams

KEY TERMS Dripstones: rock formations that are built over time as water drips through caves Stalactite: a dripstone that hangs from the ceiling of a cave Stalagmite: mound-shaped dripstone that builds on the floor of a cave Well: holes dug or drilled into the ground to reach an aquifer Artesian Well: well that’s dug into an aquifer where the water is under pressure

A LITTLE REVIEW

MORE (MOSTLY) REVIEW Although Earth’s crust appears solid, much of it is composed of soil, sediment, & rock that contain countless small openings called pore spaces. Because of the enormous volume of sediment & rock beneath Earth’s surface, enormous quantities of groundwater are stored in the pore spaces.

MORE (MOSTLY) REVIEW The amount of pore space in a material—its porosity—depends on the size & variety of particles in a material. Well-sorted, large sand grains Unsorted sand grains Well-sorted, small sand grains

GROUNDWATER MOVEMENT The region below Earth’s surface in which groundwater completely fills all the pores of a material is called the zone of saturation. The upper boundary of the zone of saturation is the water table. In the zone of aeration, which is above the water table, materials are moist, but because they are not saturated with water, air occupies much of the pores.

GROUNDWATER MOVEMENT

GROUNDWATER MOVEMENT Gravity pulls water down into the water table, while capillary action pulls water up from the water table into unsaturated soil. Soil in the zone of aeration would feel moist because of capillary water, but it would be unsaturated. The water table’s depth typically varies seasonally based on local conditions.

GROUNDWATER MOVEMENT IN SOIL VIDEO From USDA Natural Resource Conservation Service: https://youtu.be/vmo0FRAVgkM (3:10)

QUICK QUESTION With what we know about water in soils and aquifers, why doesn’t water drain all the way through the Earth’s crust? Take a couple of minutes to discuss with your table partner.

RETURN OF THE AQUIFER As we know, aquifers are underground water storage areas. They are actually layers of permeable subsurface material saturated with water. Impermeable layers—aquicludes—block groundwater flow

SPRINGS Springs can emerge from sides of valleys, at the edges of perched water tables, along faults, & from underground pathways. A spring is the result of groundwater that emerges at Earth’s surface. Springs can be caused by a variety of situations. The temperature of groundwater that is discharged through a spring is generally the average annual temperature of the region in which it is located. In some regions around the world, springs discharge water that is much warmer than the average annual temperature. These springs are called warm springs or hot springs.

GEYSERS Geysers are explosive hot springs in which water is heated past its boiling point, causing it to vaporize. The resulting water vapor builds up tremendous pressure, which fuels eruptions at the surface.

OLD FAITHFUL GEYSER VIDEO From Yellowstone NPS: https://youtu.be/4In-VEMmX_8 (4:42)

GROUNDWATER WEATHERING The processes of dissolving and precipitating calcite play major roles in forming limestone caves. A natural underground opening with a connection to the Earth’s surface is a cave. As groundwater infiltrates the cracks & joints of limestone formations, it gradually dissolves the adjacent rock & enlarges these passages to form an interconnected network of openings. A sinkhole is a depression in the ground caused by the collapse of a cave or by the direct dissolution of limestone by acidic water. Limestone regions that have sinkholes & disappearing streams are said to have karst topography.

KARST TOPOGRAPHY

DRIPSTONES Dripstones are rock formations that are built over time as water drips through caves. Stalactites are dripstones that hang from a cave’s ceiling like icicles Stalagmites are mound- shaped dripstones that build on the floor of a cave

WELLS Wells are holes dug or drilled into the ground to reach an aquifer. Overpumping from one well or multiple wells can result in a cone of depression & a general lowering of the water table. Drawdown is the difference between the original water table and the water level in a pumped well.

ARTESIAN WELLS An artesian aquifer has water that’s under pressure. The pressurized water in a well drilled into an artesian aquifer can spurt above the land surface in the form of a fountain known as an artesian well.

ARTESIAN WELL VIDEO From Little Traverse Conservancy: https://youtu.be/etTnu3sz2yg (3:13)

TICKET OUT THE DOOR K-W-L. List something you knew before today, something you want to know more about, and something you learned today.