Basic introduction
Ice
Ice period means that the surface of the earth covers the geological period of large-scale glaciers, also known as the glacial period. There is a relatively warm period between the two ice days, called the inter-ice period. There have been several ice during the history of the earth, and it is the fourth Ji Ice period.
Sign
The most important sign of the ice period is a global substantial temperature to get cold, in high latitude (including polar) and high mountain area extensively form a large area of ice cover and Mountain glacier. Since the moisture is transferred from the ocean to the ice cover area, the continental ice cover is constantly expanding, causing the sea level to decline. Therefore, the climate when the ice is prevalent is dry. The existence of the ice sheet and the change of the landline, the climate zone is also moving, and the atmospheric circulation and ocean flow have changed, which directly affects the growth, evolution and distribution of the animals and plants.
Division basis
The new generation of the big ice is due to the old, recognized glaciers of the era, scattered, the degree of research is also poor, and now there is more than the glacier in the ground. The mixed rocks of the traces, the stone tuberculosis in shale and the rock chassis with glacier wipes. The new generation of glacier relics in the new generation is generally more complete, especially in the late new generation of refrigeration, such as deposited deep sea deposition rock core, loess, etc., can record global climate and environmental changes. Since the 1970s, students scholars have used oxygen differential analysis, radioactive age determination and ancient magnetic and other methods to restore and rebuild the global climate change and sedimentation environment of the evening, as an important basis for dividing the ice. In addition, it is also common as a basis for the study and evening of the new generation of theory and the born environment and ice during the study of the resection of marine organisms, mammals, plant sporite fossils.
my country's situation
Ice time division in the high mountain region of China has been recognized by people, with the study of better Himalayas, North slope as an example, the fourth Ji Ice period is divided into : A. Eliminating the old ice hill platform established in the old ice hill platform near Xixia Bang Mafeng North slopes B. Established by the Ice Water of Nie Nie Xiong, West Side of Everest Nie Niki Di Di Dai in China. c. Dramatics in the vicinity of the Canton Temple in the Sino-Bilon Temple in the fluffy Valley and the ultimate velvet temple represent the late Kailong Temple in the world and the late velvet temple, which constitute the late New World. The Mount Everest, and some scholars also draw these two stages of two independent ice.
About the issue of the fourth Ji Ice period in China is still in debate. In 1944, Li Siguang was a template in Lushan, and the fourth Ji Ice of East was divided into Xiangyang, Da Gu, Lushan Ice, plus the last ice period of H. Von Fei Mastein, in 1937 - Dali Ice, Established the fourth Ji Ice period series in eastern China. In this regard, some Chinese and foreign scholars have always held different opinions. At the beginning of the 1980s, Shi Yafi, etc., except for Taibai Mountain, Changbai Mountain's main peak area and Taiwan Central Mountain, etc., there is a fourth Jiki Glacier, the Yangtze River, the mountain, Guangxi Guilin, Hubei Shennongjia, Beijing Xishan, Northeast Daxing'anling The lack of reliable ancient glacier evidence; China's eastern and western sections have different forms of expressions, and the eastern region does not have water, heat and topographic conditions for development into mountain Yue Glacier, just in a climate is more cold. During the period, Li Siku was confirmed by the Eastern Ancient Glacier Remains, such as the mudslide accumulated, consciously, such as ice, the fourth Ji Ice stage series, except for Dali Ice, and other ice days were lacking.
China Fourth Ji Glacier
China's 4th Ji Glacier, Li Si Guang was first discovered in the Taihang Shandong and Shanxi Basin, the Glacier in 1922. The scope includes the Northeast Changbai Mountain, Big, Xiaoxing'anling, Northern and Northwest, Taishan, Huashan, Taibai Mountain, Qinling, Wutai Mountain, Taihang Mountain, Liangshan, Yin Mountain, Helan Mountain, Southern Fujian, Guizhou, Gui, 赣,,, 西 藏Waiting for the mountain and the plateau, also spread to the eastern mountainous region and often flows from the tongue to the foothills. This big ice, can be divided into four sub-ice, three inter-ice and one ice. In the largest ice period, 32% of the world has been covered by glaciers, and a large number of ice is lagging in the mainland, causing the sea to decline by about 130 meters. The original human beings are developing in the climate change between the fourth Ji-Ice and the BBP.
We are now in the fourth Ji Da Bing period. In fact, there is a big change in the climate in the fourth Ji Duality, and there have been several times of ice and as-as-ascending period. Time is short for thousands of years, long of millions or more than ten thousand years.
In the early 20th century, the geologist according to the information on the Alps, and it was determined that there were four sub-fancy. This is: Groups of Bienie, Valentine's Ice, Risia Ice and Wulhuang Asian Ice, is a sub-ice stage between these Ice. In the future, the corresponding ABB was also found in Nordic, North America, Asia. The ABI period in my country is: Xiangyang Yaing, Daoganya Ice, Lushan - Ice and Dali Ace.
In the fourth Ji Dazhi, there is still cold and warm replacement. In the cold period, the snowline is highly lowered, the glacier advances, there is a fancy period, of which the ice and the ice of the Ice Ice during the ABBI and Lishan) have the greatest scale, and the large scale of groups is the smallest. In the warmth, the temperature rises, the snow is high, and the glacier retreats, there is a bicyzygar period. The Demns (Daxie - Lushan) Asian ice is 17-18 million years. In the fourth bing, the high latitude temperature declines, causing a permanent ice cover in the pole area; in the ABB, the glaciers have been stretched into the mid-latitude, and the ice is quarantined to high latitude during the Asian ice.
According to the scientific research, the climate is often gradient when transitioning from the Asian Ice period, and the climate is often graded, there is no clear boundary. When transitioning from the ABI period, the climate is often mutated, and there is a clear boundary line between the two. Scientists are called termination lines. There is a termination line, the ice, the climate is warmed by cold, and the climate is cold.
In the fourth Ji Dazhi period, why will there be alternative to ABB and Asian ice?
According to Yugoslav Climatologist, Milan Kevach, in the 1930s, is caused by natural small fluctuations of Earth orbit. Earth track three elements refer to: Earth track eccentricity, sloping of the ground and the position of the spring points.
The track around the sun is an ellipse, the sun is located on an oval of the ellipse. In this way, the Earth is in different positions of the track, which is different from the sun, and the solar radiant energy is different. For example, in the winter, in the summer, winter is cold, and the summer is hot and short. Earth tracks Today's eccentricity is 0.017, but the eccentric rate can be changed within 0.001-0.054. Its change cycle is about 9,60,000. The change in eccentricity affects the day distance, which affects the solar radiation intensity, causing the climate change on the Earth.
Where is the position of the geosetic point in the earth's mutual point in the spring point, which will affect the start of the season, which will also change the time in the near-day and far-resection. The Earth moves in the spring points along the global mobility track to west, approximately every 2nd yuan, the position of the spring is moved on the earth's mutual track. The time of spring is flying, every 70 years will postpone a day. Today, the northern hemisphere is far from the summer, and the summer is 8 days from the winter season. After about 10,000 years, it will turn into winter, in the winter, it will be more than 8 days in summer. That is, it is not too cold and short in winter, will become a cold and long winter.
The track is tilted and called Huang Dicheng, which is the cause of the four seasons on the earth. The change in the tilt of the track will result in a change in the latitude of the return line and the extremely circle to change the season on the earth. The track is inclined to change the returns line between the latitude of 22.1 ° -24.4 °, making the extremely circle between 67.9 ° -65.76 °. Change time period 4 1000 years. When the track is increasing, the latitude of the return line is increased, the latitude latitude is lowered, the total amount of solar radiation in high latitude increases, the winter is hot, the temperature is poor, and the total amount of solar radiation in low latitude is reduced. When the track is sloped, the high latitude winter is cold in summer, the temperature is poor, and the summer temperature is more conducive to the development of glacier.
Effect of
Ice is significant for the global impact. 1 The presence of a large area of ice change has changed the distribution of surface water. At the end of the new generation of ice, the water circle moisture gathered in terrestrial and caused approximately 100 meters from the global sea level. If the ice is all melted today, the global sea level will rise 80 to 90 meters, and many large cities in the world will be overwhelmed. 2 The large ice cover at the time of the ice is thousands of meters, so that the local pressure of the crust is under slow down, some are dropped by 100 to 200 meters, and the substrate of the Antarctic mainland is reduced below the sea level. With the disappearance of the 4th ice cover, the crust is slowly rising. This housing equalization movement is still continuing. 3 Ice changes have changed the distribution of global climate bands, and a large number of popular animals and flora were extinct.
Genesis
Scholars have raised all kinds of explanations, but there is no satisfactory answer. Incident, there are mainly astronomical and geophysical conciseness.
Astronomical Because
mainly considers the relationship between the sun, other planets and the earth. 1 The cycle change of the sun is affecting the climate of the earth. When the sun is weak, the amount of radiation is reduced, the earth is getting cold, and the ice climate appears. Milankovic believes that the reduction in solar radiation in the summer and half year is a possible factor that causes ice. 2 The cycle change of the Earth Yellow Direction is caused by changes in temperature. Huang Dicong refers to the integrity of the zodiac and Tianzhi, and its change is mainly affected by the planetary perturbation. When Huang Qianjiao is large, winter and summer has increased, and the annual average anniger is minimal, so that the low latitude area is in a cold period, which is conducive to the glacier generation.
Physics causes
More influencing factors, there is an atmospheric physics, and there are also geographical geology. 1 Influence of atmospheric transparency. Frequent volcanic activity, such as the atmospheric layer, is full of volcanic ash, low transparency, reducing the amount of solar radiation, resulting in cooling. 2 The effect of the construction movement. The structural movement causes land lifting, land displacement, visual movement, change the seafood distribution and circulation, which makes the earth get cold. The feedback effect of cloud, evaporation, and ice reflections further makes the earth getting cold and prompts the ice. 3 The shielding effect of CO2 in the atmosphere can prevent or reduce the loss of heat of the surface. If the CO2 content in the atmosphere increases to 2 to 3 times today, the polar temperature will rise by 8 to 9 ° C; if the CO2 content in the atmosphere is reduced by 55 ~ 60%, the temperature in the midwest is 4 to 5 ° C. In geological elements, volcanic activities and biological activities make great changes in the CO2 content in the atmosphere, which may have ice during the reduction of CO2 shielding to a certain extent.