Geology Reference
In-Depth Information
OUTLINE
Introduction
Groundwater and the Hydrologic Cycle
Porosity and Permeability
The Water Table
Groundwater Movement
Springs, Water Wells, and Artesian Systems
Groundwater Erosion and Deposition
GEO-INSIGHT: The Burren Area of Ireland
Modifi cations of the Groundwater System and Its Effects
GEO-FOCUS: Arsenic and Old Lace
Hydrothermal Activity
Geo-Recap
OBJECTIVES
At the end of this chapter, you will have learned that
Groundwater is one reservoir of the hydrologic cycle and accounts
for approximately 22% of the world's supply of freshwater.
Porosity and permeability are largely responsible for the
amount, availability, and movement of groundwater.
The water table separates the zone of aeration from the under-
lying zone of saturation and is a subdued replica of the overlying
land surface.
Groundwater moves downward because of the force of gravity.
In an artesian system, groundwater is confi ned and builds up
high hydrostatic pressure.
Groundwater is an important agent of both erosion and
deposition and is responsible for karst topography and a
variety of cave features.
Modifi cations of the groundwater system may result in
lowering of the water table, saltwater incursion, subsidence,
and contamination.
A variety of cave deposits such as stalactites, stalagmites, and curtains can be
seen in caves such as this one in the Shenandoah Caverns, in Virginia.
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