Types of Waterfalls
You may have heard two other terms used to define a waterfall: cascade and cataract. Although they both describe waterfalls, they mean slightly different things. A cascade is the most common term and usually describes a waterfall with any kind of irregular surface underneath the water. It flows down in a fairly low volume, and several stages can make up one large waterfall. A cataract, on the other hand, is a waterfall with larger, more powerful volumes of water and is typically accompanied by rapids.
Now that we've explained the terminology, let's examine some different types of waterfalls. The most basic and recognizable type of waterfall is the plunge waterfall. This happens simply when a river spills out water over a ledge, and the water descends vertically without coming into contact with any of the rock on the way down -- it just crashes right into the plunge pool. This type of waterfall would take longer to retreat, since the hard rock over which the water is flowing is more resistant to erosion.
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A block or sheet waterfall is formed from a wide river -- when the water spills over the edge, it looks like a big sheet, especially if the flow isn't broken by any stray rocks protruding from the back-wall. A block waterfall is usually wider than it is high. Similar in nature is the curtain waterfall, which is simply taller than it is wide, but still looks like a long sheet.
Horsetail waterfalls are in constant or semi-constant contact with rocks, which may erode faster than other types because of constant runoff.
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Because the geography of the land is never limited, a waterfall can be one of these things or have any combination of them. For instance, a punchbowl waterfall might descend into a small plunge pool, but the plunge pool might quickly lead to another ledge where the water descends as a plunge waterfall. These waterfalls are generally called tiered. There are seemingly endless possibilities, which is probably the biggest reason people look for and are interested in new waterfalls.
A punchbowl waterfall happens when water from a wider river flows through a narrower area and out into the plunge pool -- the water appears to punch through the thin space and into the open.
For lots more information about waterfalls and other geological formations, see the next page.