Springs and Geysers
Whenever water beneath the ground meets the surface, aspringis created (Figure13.22).
This is a natural point where groundwater emerges on the Earth’s surface. When water
from a spring flows downhill, it can create a stream. If it does not move downhill, it may be
termed aseep,and may create a pond or lake. Depending upon the source of water, the
spring may be either constant, or may only flow at certain times of year.
Figure 13.22: Big Spring in Missouri lets out 12,000 liters of water per second(Left). Other
springs are just tiny outlets like this one.(Right) ( 19 )
Some minerals may become dissolved in groundwater, changing the water’s flavor. Even
carbondioxidecandissolveinthegroundwater, causingthewatertobenaturallycarbonated.
This water is sometimes sold as “mineral water.”
Groundwater can be heated by magma below the Earth’s surface. The heated water can
createhot springs, springs with water that is naturally hot (Figure13.23). Some hot
springs are used as natural hot tubs and are considered therapeutic and spiritual by some
people. However, hot springs can be dangerous, too. Their temperatures can be exceedingly
hot, dissolved substances can be poisonous, and organisms like viruses and bacteria can
spread disease. Be sure a hot spring is safe before entering one.
When heated groundwater is trapped in narrow spaces, the pressure builds up and causes
water to actually rocket upward. A geyser is the result of such a pressurized spring. Most
geysers do not erupt constantly, but rather in periodic spurts, because pressure decreases
during an eruption and then increases again after an eruption. Old Faithful, probably the
most famous geyser in the world, got its name for erupting in regular cycles lasting 90
minutes (Figure13.24). Its eruptions last for a couple of minutes and discharge 15,000 to
30,000 liters of water during each eruption.
Wells
A well is an artificial structure created by digging or drilling in order to reach groundwater
present below the water table. In Figure13.25, you can see how a well penetrates the