وبلاگ خانه تبدیل شباهنگ مرکز تخصصی تبدیل صدا و تصویر
Plants provide habitat and food for many forms of animal life, from microscopic rotifers filtering tiny algae to zooplankton that hunt larger algae, to insects, fish and aquatic mammals that eat even larger plants or animals. A change in any part of this food web reverberates through the system in subtle or even dramatic ways. Conditions that surround and affect an organism or community. Glacial lakes: By far the most important players in the formation of lakes are the catastrophic effects of glacial ice movements that took place 10,000 to 12,000 years ago. Gigantic layers of ice and snow form in climates where snow falls but does not melt. The glaciers covered an area from the Atlantic Ocean to the Rocky Mountains with more than a kilometer of ice. Although these glaciers eventually melted, ten percent of the earth is currently covered by glaciers. Some of these glaciers can still be seen in the mountainous regions of the United States and Canada. Non-native species that alter the natural habitat of an ecosystem.
Algonquin Lake was a large glacial lake that existed about 11,000 years ago when the Laurentian ice sheet retreated north of the Great Lakes region. Algonquin Lake covered an area of approximately 100,000 square miles with a maximum depth of 1,500 feet. Geologists found that the coastline steadily increased as it moved northward. Lake Nippising formed when the Wisconsin ice sheet retreated northward, marking a peak in the water level of the Great Lakes. Lakes Michigan, Huron and Superior have been combined into a single body of water. The isostatic rebound raised north bay to the level of two previously existing lakes. In 1,600 years, erosion slowly lowered the lake level to present-day Lake Superior. Chippewa Lake was an lower stage of Lake Michigan that formed when the retreat of the ice sheet exposed the St. Lawrence Seaway, a sea-level outlet. This was the result of significantly lower lake levels called Chippewa Low Levels. There is now a gorge carved into the flow of Chippewa Lake, which lies beneath the Strait of Mackinac.
Solution lakes: Lakes can form when underground deposits of soluble rock are dissolved by water flowing into the area, resulting in depression in the soil. Rock formations of sodium chloride (salt) or calcium carbonate (limestone) are most likely to be dissolved by acidic water. Once the groundwater has dissolved the rocks below the surface, the top of the earth collapses, usually forming a round lake called a solution lake. Typically, depressions are deep enough to extend below the groundwater level and are permanently filled with water. Solution lakes are common in Michigan, Indiana, Kentucky and especially Florida. Lake DistrictThe Lake District is a famous wilderness area in the north of England. Lake District National Park is one of the most popular parks in the country. In addition to lakes, the Lake District is filled with mountains and hills, valleys and streams, bogs and plains. The Lake District was a favorite spot of the so-called Lake Poets, a group of 19th century English writers, including William Wordsworth and Samuel Taylor Coleridge. The formation and location of the Great Lakes is a direct result of ancient glaciation and geology, but the exact age of the lakes is not known. Scientists estimate that they are between 7,000 and 32,000 years old, with the lakes changing in shape and size over the millennia.
But everyone agrees that the process began millions of years earlier with the movement of continents and a series of huge glaciers that run through the landscape. Beginning in the Paleozoic, which included the Cambrian, Ordovician, and Silurian, where new life forms emerged, large inland seas divided parts of North and South America, flooding the landforms we know today completely underwater. As the Paleozoic seas retreated, powerful geographic forces continued to displace continents and change the landscape. Today`s Great Lakes have six quadrillion gallons of water, with only the polar ice caps and Lake Baikal containing more. Lake Superior has the lowest point at a depth of 1,333 feet. .
