A waterfall is a place where a flowing river falls suddenly and almost vertically.
In most cases, rivers smooth out irregularities in their flow through erosion and silting.Over time, the longitudinal section of a river (the slope curve) forms a smooth arc: it is steepest at its source and mildest at its mouth.The waterfall interrupts the arc,
showing the progress of the erosion process.A waterfall is also called a falls or sometimes a waterfall, the latter being used especially when talking about a large quantity of water.The lower and steeper falls are called cascade, the name often given to a series of small falls along a river.Some sections of a river have a gentler slope, but where the river slope increases locally, there are corresponding turbulence and white water. These sections of a river are called rapids.
In some cases, the location of the falls receded upstream due to the erosion of a cliff or ridge by the current, while in other cases the erosion tended to be deep downward and to cut diagonally across the entire section containing the falls.Over time, a combination of these factors makes it inevitable that any waterfall that might form will disappear.The river's energy will eventually produce a relatively smooth,
A longitudinal section with an upward concave surface.The amount of energy available for erosion of the base of the falls is high even when the gravel used as a tool for river erosion is not present.One of the characteristics associated with waterfalls of any size, as well as with flow and height, is the presence of plunge pools.A plunge pool is a basin that has been excavated from a channel below the fall.In some cases, the depth of the pool may approximate the height of the steep cliff that causes the falls.The plunge pool eventually caused the slope of the cliff to collapse and the waterfall to retreat.
The cliff that causes the fall will continue to collapse under the force of the current, causing the falls to recede upstream and drop in height, eventually causing the falls to disappear.
There are several conditions for the formation of a waterfall.
One of the most common reasons for the waterfall's existence is the difference in rock types.Rivers cross many lithographic boundaries.If a river flows from a hard rock bed to a softer rock bed, the softer rock bed is likely to erode faster and the slope at the junction of the two rock types is steeper.This happens when a river changes direction and reveals a junction between different rock beds.Niagara Falls make up the United States
Part of the border with Canada has a mottled dolomite roof rock on the riverbed, resting on a series of softer shales and sandstone.The Niagara river has climbed over the walls of the dolomite and fallen down into a large pool below, its tumbling waters eroding the shale, hollowing out the holes in the dolomite, and sloughing off the cliffs forever.
In another case, a chunk of ancient lava pushed up from beneath the riverbed. As the rock hardened, it formed a "wall" in the channel, blocking the water.This is how China's hukou waterfall in the Yellow River was created.
In the third case, ancient glaciers cut into the valley, creating cliffs on both sides, on which waterfalls form.
Another related reason for the falls is that the riverbed is lined with hard rock.A series of large waterfalls have appeared on the Nile, and the Nile water has eroded the riverbed enough to expose the hard crystalline basement rock.
And waterfalls are formed less by the characteristics of rock formations and more by the structure and shape of the land.Elevated upland basalt, for example, forms a hard platform on which rivers create waterfalls, as they do in Northern Ireland.On a larger scale, the rocky facade of the southern half of Africa -- a high plateau surrounded by steep slopes -- produces waterfalls and rapids on most of the region's major rivers, including Livingstone Falls on the Congo river and Augrabies on the orange river.In general, as the slope of the mountain terrain increases, so does the number of waterfalls.
River erosion and geological features are not the only factors that produce waterfalls.Tectonic movements along the fault bring hard and soft rock together, creating the falls.The sharp drop in bed sea level increases the erosion and causes the crack points on the bed to recede upstream (in other words, the sharp change in slope indicates the change in base water level of the bed).Depending on sea level,
river flow and geological characteristics, among other factors, a river drop or jet stream may develop at a point on the riverbed where cracks appear.Glaciation has resulted in numerous waterfalls, where valleys have been overdeepened by glacial erosion, leaving tributary valleys high on either side of steep valleys.Yosemite falls, a glacier-carved Yosemite waterfall in California, fell from a suspended valley 436 meters (1,430 feet) high.
