Click on image for a larger picture and more info.
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Click on image for a larger picture and more info.
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Click on image for a larger picture and more info.
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Waterfalls are literally places in
steep segments of rivers where water falls vertically. Sometimes waterfalls
such as Niagara Falls are termed cataracts, when a large volume of water
is involved. Also, waterfalls can be termed cascades, which are a series
of small falls. All waterfalls are produced by stream erosion.
The rate at which erosion occurs depends greatly on the height,volume,
and type and structure of rocks involved in the waterfall. At the base
of most waterfalls is a plunge pool. A plunge pool is a basin scoured out
of the river channel beneath the falling water. These pools eventually
undercut the resistant strata and cause the collapse of the face of the
waterfall. As a result, the position of the waterfall migrates upstream.The
most common reason for the development of waterfalls is a difference in
rock type. Rivers cross many lithologic boundaries, and when they pass
from a resistant rock bed to a softer one, it is likely that the soft rock
will erode more quickly. Other waterfalls are caused by specific geologic
structures. For example, a basalt flow may provide a resistant platform
at the edge of which rivers produce waterfalls. |