williammorgoscigomia

Waterfalls are commonly formed in the upper course of a river in steep mountains. Because of their landscape position, many waterfalls occur over bedrock fed by little contributing area, so may be ephemeral and flow only during rainstorms or significant snow melt. The further downstream, the more perennial a waterfall can be. Waterfalls can have a wide range of widths and depths. Aerial view of Victoria Falls on the Zambezi River in southern Africa. The cloud formed by the mist is called cataractagenitus. When the river courses over resistant bedrock, erosion happens slowly and is dominated by impacts of water-borne sediment on the rock, while downstream the erosion occurs more rapidly. As the watercourse increases its velocity at the edge of the waterfall, it may pluck material from the riverbed, if the bed is fractured or otherwise more erodible. Hydraulic jets and hydraulic jumps at the toe of a falls can generate large forces to erode the bed,especially when forces are amplified by water-borne sediment. Horseshoe-shaped falls focus the erosion to a central point, also enhancing riverbed change below a waterfalls. A process known as "potholing" involves local erosion of a potentially deep hole in bedrock due to turbulent whirlpools spinning stones around on the bed, drilling it out. Sand and stones carried by the watercourse therefore increase erosion capacity. This causes the waterfall to carve deeper into the bed and to recede upstream. Often over time, the waterfall will recede back to form a canyon or gorge downstream as it recedes upstream, and it will carve deeper into the ridge above it. The rate of retreat for a waterfall can be as high as one-and-a-half metres per year.

Group of Pigeons Flying Formation in Front of Masjid ' Ya Allah '

In recent times it is considered by some to be more accurate to refer to the New World buffalo as a bison, since it is not in the same genus as the two buffalo of the Old World. The argument is debatable however, because the old world buffalo do not share a genus either, and there is a fourth animal called the gaur or "Indian bison", which belongs in yet another separate genus, with different lineage. The fact is, there is little confusion in identifying the animal, particularly when the term "American buffalo" is used, and just as we commonly say "dog" and "cat" instead of "Canine" and "feline", the common term should not be considered incorrect. The animal has been referred to as a "buffalo" - which is a form of a French word "boeuff", simply meaning "large cow", and from which the word "beef" also comes - throughout its history, and the word "buffalo" has been used in reference to the American animal as far back as 1635. There is a European bison as well, that, although separated by oceans, looks very much like the American bison or buffalo, and is basically considered to be the same animal. The Old World "buffaloes" are the Cape buffalo of Africa, and the domesticated water buffalo of Asia. The most obvious difference is that they lack the thick, woolly fur of the American buffalo, and are usually black in color. The horn shape is different as well, with the Old World buffaloes having longer horns that curve back in towards each other. Finally, all of these animals are bovines from the subfamily bovinae, which are all basically cow-like animals with cloven hooves and multi-chambered stomachs.