What is the largest plain in America?

The plains of the United States are vast, and there are more plains than other countries. The largest plain in the United States is the Great Plains. I have compiled relevant information for you, please refer to it.

The largest plain in America? American plain

The Great Plains lies in the middle of the United States. This is one of the most famous plains in the world. Its appearance is flat and slowly inclines to the east, and its climate belongs to semi-arid continental climate. In winter, Leng Xia is hot, and zonal plants are grassland vegetation. Due to unreasonable reclamation, the black storm once raged, and after taking a series of environmental protection and restoration measures, it became an important grain export base in the United States.

geographical position

As a natural region, the American Great Plains is one of the most famous plains in the world, which actually extends to Canada. In the United States, its basic boundary is: the contour line of the foothills of the west landing base at an altitude of 1800 meters; East to the Mississippi Valley, about 300 meters above sea level along the contour line; North to saskatchewan river; South to southern Texas. American academic circles have different understandings of the eastern boundary of the Great Plains. It is generally believed that 97 years? Nearby.

The Great Plains of the United States includes Montana, Wyoming, Colorado, New Mexico, North Dakota, South Dakota, Nebraska, Kansas, Oklahoma and Texas. It is 640 kilometers wide from east to west and about 2400 kilometers long from north to south (including Canada). Among them, the land area accounts for about one-fifth of the continental area of the United States (65,438+0,536,000 square kilometers), with a population of 5.5 million, accounting for only 3.7% of the population of the United States. The population density is very low, with less than 5 people per square kilometer. Except for the edge, it is a fairly complete plain, which slopes slowly from west to east, and the human eye can hardly feel its slope, which is only about 2 meters per kilometer. Walking through this vast land along Highway 80 across America, I feel open-minded. A scholar studying in the United States wrote: "The mountain source is the soul of poetry, the land should be pitiful, the burning things are beautiful, the grain and the beam are overflowing, and the sunset is endless. People have thoughts to solve doubts, there are hills and valleys in their chests, and life is everywhere. "

Geological and geomorphological characteristics

The underlying bedrock is marine and shallow sedimentary rocks, mainly composed of gently inclined shale, limestone and sandstone. The thickness can reach 5 kilometers. Most of the surface layer in this area is composed of young continental sedimentary proluvial, and the northern part is discontinuous covered by Pleistocene glacial materials, resulting in loess deposition. Generally speaking, the geological situation is relatively simple and the geological movement is not very strong. On the other hand, there are two areas in the Great Plain that are in obvious contrast: L. Wasteland: an easily eroded area is formed, and its bedrock is shale. Occasionally, a one-off rainstorm will cause quite serious erosion on the ground, forming a unique deep valley cliff, and hills and hills hundreds of feet above the surrounding surface appear in various places; 2. Blackshear: This area is much higher than the surrounding plains, with abundant rainfall, which makes pine forests and birch forests flourish. Among them, the bedrock is sandstone, which is a good water storage layer and the main water source in eastern South Dakota.

The appearance of the Great Plain is flat and slowly inclines eastward, but it is only blocked by the ups and downs of three areas: Heishan District 1: It is a crystalline rock block (about 50 Li long and 20 Li wide, that is, 80? 32 kilometers), invaded the flat plain deposits, forming ups and downs; 2. Along the border from Colorado to New Mexico, the ancient erosion surface maintained by lava covers across the plain; 3. The Songshuling fault (near the line from Nebraska to Wyoming) has broken the integrity of the plain, and this area has experienced different degrees of erosion. At the same time, due to the climate and soil conditions, the Great Plains is also called "dust storm area".

Climatic characteristics

The climate belongs to semi-arid continental climate, and Leng Xia is hot in winter. When there is a cold wave in winter, the temperature can drop a lot and severe frost can be distributed in Texas. But if we call chi-nooks warm air in winter, it will be extremely beneficial to agriculture and animal husbandry. In winter and spring, this kind of wind often blows to the southeast, the ice and snow melt and the temperature rises, which is beneficial to livestock grazing. However, when the winter wind, which is called snowstorm, strikes, storms are produced, accompanied by heavy snow, which brings great disasters to animal husbandry. In summer, it is very hot during the day and very cold at night, with great temperature difference. Compared with the hottest month of the year, the temperature difference in Leng Yue is over 33℃. The annual precipitation is less than 500 mm, and the local, seasonal and interannual changes are considerable, which poses a great threat to the stability of agricultural production.

On the great plains, the main types of weather disasters are as follows: 1, drought: with certain periodic changes; 2. Sandstorms: There are many sandstorms due to the drought and loose land and the violent disturbance of strong wind and airflow; 3. Floods: Especially in summer, due to the influence of heavy rain, drainage in plain areas is difficult and floods occur from time to time; 4. Lu Longjuan: It will happen frequently every year since April. Although it is local, it is extremely destructive.

Rivers on the plains basically originate in the Rocky Mountains, cross the plains from west to east, and finally flow into the Mississippi River. The famous rivers are Missouri, Pratt and Arkansas.

Typical grassland

The zonal plant type is grassland vegetation, which consists of short grass (also known as buffalo grass) and sporadic deciduous trees. The most common is the three-leaf poplar distributed along the plain valley, and the pine trees are distributed on stony non-agricultural land. Due to great human influence, grassland destruction and over-reclamation, the natural vegetation types on the Great Plains are very unstable. The natural grassland before development is suitable for large-scale grazing. Once destroyed, grasslands are extremely difficult to recover. Therefore, the natural protection of vegetation and soil on the great plains has always been a major issue.

The soil is fertile, suitable for agricultural planting and high in organic matter content. However, without adequate humidity and biological protection, it is extremely vulnerable to wind erosion, and the severity of wind erosion is amazing.

Agricultural change

/kloc-in the middle of the 0/9th century, whites gradually moved westward, invaded the Midwest of the United States step by step and settled in the Great Plains. They drove away the Indians, replaced the bison herd that was almost extinct by them with domestic cattle, and later developed the shepherd industry, gradually forming an economy dominated by animal husbandry. It lasted until the 1980s, which coincided with the long rainy season (about 14) and the high price of wheat at that time, so many natural pastures were reclaimed as farmland, but the good times did not last long, and then there was a dry year. These below-normal precipitation seriously threatened crops and made these farmers unprofitable, so they had to give up wasteland. When another rainy season comes, go back to your original job and cycle again as usual. As a result, it led to a serious vicious circle, because after the grassland was destroyed, it was extremely difficult to restore it, resulting in bare land and weakened anti-erosion ability. Drought and strong winds are inevitable, and the most typical one is the "black storm" in the 1930s, which is the concentrated expression of the above vicious circle. An unprecedented black storm occurred in the western United States from 65438 to 0934. Where the storm passed, streams were cut off and wells dried up.

American black storm

For example, on May 2nd, 1934 and 12 were severely punished. On this day, a cloud of dust and fog blew from the western border of Canada and several states adjacent to the grassland in the western United States, and it pushed eastward at the speed of 60- 100 miles per hour. The dust and fog carried 300 million tons of fertile topsoil in the arid area of the western United States, crossed two-thirds of the territory of the United States, reached the east coast of the United States, and finally poured into the Atlantic Ocean hundreds of miles offshore. This is the famous "black storm" in history. This huge dust belt, which shocked the world, was 1500 miles long from east to west, 900 miles wide from north to south and 2 miles thick, which seriously reduced the yield of winter wheat in the United States at that time, which was about 102 billion Jin lower than the average yield in the past10 years.

Due to unreasonable human activities, land reclamation and grassland destruction. In the western United States in 1870, the cultivated land area was less than18 million mu, but in 1930 60 years later, it had been expanded to110 million mu, with a corresponding increase of more than 60 times. In this way, the original grassland is destroyed, and the ecological balance of the agricultural biosphere, which has reached stability after years of adjustment, is destroyed, resulting in soil exposure and accelerated wind erosion. Coupled with the dry climate and insufficient water resources, it has caused great disasters. According to the investigation, the black storm scraped off the soil surface layer with an average thickness of 5-30 cm and destroyed about10 million mu of farmland.

Since then, the agriculture in the Great Plains has attracted the attention of all parties, and some measures have been taken to gradually stabilize the agricultural production in this area. These measures can be summarized as follows: 1. Expanding irrigation; 2. Mechanization; 3. Increase the application amount of chemical fertilizer; 4. Use pesticides and herbicides; 5. Strengthen soil protection.

Due to various measures, the Great Plains has become the granary of the United States. The wheat belt and corn belt in the United States are mainly located in the Great Plains and become the base of American grain export. With the coming of 2 1 century, the world population has increased dramatically, and the shortage of food supply has become an increasingly serious problem. Improving the agricultural production capacity of the Great Plains will effectively guarantee the life support system of the earth and make due contributions to the sustainable development of the earth.