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Also known as the "Quaternary glacial period". The climate cooled at the end of the Tertiary period,
quaternary
Early, cold
Climatic zone
Migration to the middle and low latitudes led to the extensive development of ice sheets or glaciers in the high latitudes and mountains. This period began about 2 to 3 million years ago and ended about 10,000 to 20,000 years ago. It's huge. At the southern edge of the European Ice Sheet, it can reach about 50° N latitude. in
North America
The front of the ice sheet extends south of 40° N;
Antarctica
The ice sheet was much larger than it is today. Including those near the equator
Mountain glacier
and
Piedmont glacier
All once extended down to a lower position.
[1]
- Chinese name
- Quaternary glacial period
- Foreign name
- Quaternary glaciation
- alias
- Glacial age
- World form
- The Earth's surface is covered with massive glaciers
- Important mark
- Global temperatures are cooling dramatically
An ice age is when the Earth's surface is covered with massive glaciers
Geological time
, also known as
Glacial age
. Between the two ice ages was a relatively warm period called
Interglacial period
. There have been many ice ages in Earth's history, such as the most recent
quaternary
The ice Age.
The most important symbol of the ice age period is the global temperature cooling, the formation of large areas of ice sheets and ice sheets in the middle and high latitudes (including the polar regions) and the high mountains
Mountain glacier
. As water moves from the ocean to the ice sheet,
Continental ice sheet
Expanding and thickening, causing sea level to drop significantly. Therefore, the climate during the prevailing ice age was dry and cold. The presence of ice sheets and changes in land and sea conditions,
Climatic zone
Changes in atmospheric circulation and ocean currents directly affect the growth, evolution and distribution of plants and animals.
Cenozoic
former
The Great Ice Age
Recognizable because of its age
Glacial remains
It is scattered and incomplete, and the degree of research is also poor. Nowadays, it is mostly based on the mixed moraines with glacial scratches in the strata, chert nodules in the shale and bedrock chassis with glacial scratches. The glacial remains of the Cenozoic glaciation are generally intact, especially the late Cenozoic glaciation, for example, the sedimentary continuity is good
Abyssal deposit
Rock core, loess, etc., can record the global climate and environmental changes more completely. Since the 1970s, researchers have used oxygen isotope analysis, radiometric dating and paleomagnetic methods to recover and reconstruct the global climate changes of the late Cenozoic era
Depositional environment
As an important basis for the division of ice age. In addition, organisms containing Marine organisms, mammals, and fossil plant palynes
stratigraphy
,
Geomorphic analysis
Sedimentary petrology and paleosol methods are also often used as the basis for studying the late Cenozoic environment and the division of ice ages.
Western China
The division of ice ages in alpine areas has been well recognized for better study
Himalayas
Mount Everest
District north slope for example,
quaternary
Ice ages are divided into:
a. Basis
Shishapangma Peak
The old moraine platform near the north slope was established early
Pleistocene
the
Shishapangma
Ice age
b. Based on the ice-water moraine deposits of Nieixiongla Plateau on the west side of Qomolangma
The Middle Pleistocene
The Nynyishongla Glacial period.
c. in
flannel
In the valley
Keelung
The ruins of the conglomerate group near the temple and the Rongbu Temple upstream
Terminal moraine
Ridge separation
Late Pleistocene
The early Keelung Temple stage and the later Rongbuji stage constitute the late Pleistocene
Mount Everest
Ice age, some scholars have divided these two stages into two independent ice ages.
With regard to
Eastern China
The question of Quaternary glaciation is still under debate. In 1944, Li Siguang used Lushan Mountain as a model to divide the Quaternary ice age in eastern China from old to new into Poyang, Dagu,
Lushan Ice Age
In addition, the last ice Age proposed by H.von Fishman in 1937
Dali glaciation
The Quaternary glacial series in eastern China was established. Some Chinese and foreign scholars have been holding different opinions on this. In the early '80s,
seya
Etc proposed, divided
Mount Taibai
,
Changbai Mountain
There are high mountains above 3,500 meters above sea level, such as the main peak area and the Central Mountains of Taiwan
Fourth glacial remains
In addition, the middle and lower reaches of the Yangtze River
Guilin, Guangxi
, Hubei
Shennongjia
,
West mountain of Beijing
, the Northeast
The Greater Khingan Mountains
There is no reliable evidence of ancient glaciers.
Eastern China
And the west in the Quaternary glacial period of the form is not the same, the eastern region does not have the development of
Mountain glacier
The water, heat and terrain conditions were only in a period of relatively cold climate. The eastern ancient glacial remains confirmed by Li Siguang are not of glacial origin, such as debris flow accumulation mistaken for moraines. Except the Dali glaciation, the Quaternary glaciation series in eastern China are all lacking in basis.
Quaternary glaciers in China
China
Quaternary glacier
It was Li Siguang who first worked in 1922
Taihang Mountains
Dongluji
Shanxi Datong
Found in the basin, the range of glaciers includes the northeast Changbai Mountain, Great,
Lesser Khingan Mountains
Laoshan Mountain in the north and northwest,
Mount Taishan
Huashan Mountain, Taibai Mountain,
Qinling Mountains
Wutai Mountain, Taihang Mountain, Luliang Mountain,
Yinshan Mountain
The mountains and plateaus of Yunnan, Guizhou, Guangxi, Jiangxi, Zhejiang and Tibet in the south also spread to the eastern mountains and are often tilted towards the ice tongue
Foothill plain
Overflow. This glacial period can be divided into four sub-glacial periods and three sub-glacial periods
Interglacial period
And an ice post. During the largest ice age, 32 percent of the world's continents were covered by glaciers, and a large amount of ice remained on the continents, causing sea levels to drop by about 130 meters. Primitive humans are here
quaternary
During the glacial and interglacial climate changes, modern humans developed.
We say that we are now in the Quaternary glacial period, in fact, the Quaternary glacial period in the climate has also been a great change, there have been several sub-glacial and sub-interglacial periods, the change time is as short as thousands of years, as long as tens of thousands of years or hundreds of thousands of years.
In the early 20th century, geologists based
Alps
The data of the region determined that there were four sub-glacial periods. These are the Qunzhiya, Mindeya, Lisya and Wumuya glaciations, and in between these subglaciations are subglaciations
Interglacial period
. Later, corresponding subglacial periods were also found in Northern Europe, North America, Asia and other places. The corresponding sub-glaciations in China are: Poyang Sub-glaciation, Dagu Sub-glaciation, Lushan Sub-glaciation and Dali Sub-glaciation.
in
quaternary
During the Great Ice Age, there were still cold and warm changes. During cold periods, the snow line drops in height,
Glacial advance
Minde (Dagu in China) and Lishan (Lushan) had the largest glacial scale, and Qunzhi had the smallest glacial scale. During the warm period, the temperature rises, the snow line height rises, the glacier recede, and there is a subinterglacial period. Minde Yilis (Dagu - Lushan) subinterglacial period lasted for 170,000 ~ 180,000 years. During the Quaternary glacial period, the temperature at high latitudes dropped sharply, resulting in the formation of permanent ice sheets in the polar regions. During the subglacial period, the glacier stretched all the way to
mid-latitude
It retreated to higher latitudes during the subinterglacial period.
According to scientific research findings, from Asia
Interglacial period
During the transition to the subglacial period, the climate often follows a gradual pattern with no clear boundary. During the transition from subglacial period to subinterglacial period, the climate is often in abrupt form, and there is a clear correlation between the two
Demarcation line
. Scientists call it a termination line. A terminating line appeared around 11,000 years ago, during the interglacial period, the climate changed from cold to warm.
In the Quaternary glaciation, why is there a subglacial and subinterglacial alternation?
In accordance with
Yugoslavia
climatologist
Milankovich
The theory, proposed in the 1930s, was due to
Earth orbit
The three elements are caused by natural small fluctuations. The three elements of the Earth's orbit are the eccentricity of the earth's orbit, the tilt of the Earth's axis and the position of the equinox.
The earth goes round the sun
The orbit is an ellipse with the sun at one of the focal points of the ellipse. In this way, the earth is in different positions of the orbit, the distance from the sun is not the same, and the solar radiation energy obtained is different, such as winter at perihelion, summer at aphelion, winter is cold and long, summer is hot and short. The eccentricity of the Earth's orbit is currently 0.017, but eccentricity can vary from 0.001 to 0.054. It fluctuates every 96,000 years. Changes in eccentricity
Sun-earth distance
And thus affect
Solar radiation intensity
Causing changes in the earth's climate.
The position of the Earth in the Earth's orbit at the vernal equinox will affect the beginning and end of the seasons, as well as the timing of perihelion and aphelion. The position of the Earth at the vernal equinox moves slowly westward along the Earth's orbit, and about every 21,000 years, the position of the vernal equinox moves once in the Earth's orbit. The Spring Equinox is delayed by one day every 70 years. Today, summer in the northern Hemisphere is far away, and it is eight days longer than winter. After about 10,000 years, it will become winter and winter will be eight days longer than summer. In other words, the winter that is not too cold and short will become a cold and long winter.
Track tilt also known as
The intersection Angle of the yellow
Is the reason for the four seasons on Earth. Ground track
inclination
The changes that will lead to
Regression line
and
Polar circles
The latitude of the Earth changes, thus changing the seasons on the Earth. The tilt of the earth orbit causes the regression line to vary between 22.1° and 24.4°, and the polar circle to vary between 67.9° and 65.76°. fluctuant
Time cycle
41,000 years. When the inclination of the earth orbit increases, the latitude of the tropic line increases and the polar latitude decreases
Total solar radiation
Increase, winter cold and summer heat,
The temperature varies from year to year
The annual total solar radiation at lower latitudes decreases with the increase. When the inclination of the earth orbit decreases, the high latitude is warm in winter and cool in summer, and the annual temperature difference decreases, and the lower summer temperature is more conducive to the development of glaciers.
[2]
The global impact of the ice age was significant.
① The presence of large ice sheets has changed
Surface water body
The distribution of... On the evening of
Cenozoic
During the Great Ice Age, the water in the hydrosphere concentrated on the land and caused the global sea level to drop by about 100 meters. If all of today's surface ice were to melt, global sea levels would rise by 80 to 90 meters, flooding many of the world's largest cities and lowlands.
The thickness of the large ice sheet during the ice age was thousands of meters, so that the local crust was under great pressure and slowly fell, and some were pressured by 100 to 200 meters.
Antarctic continent
Its base was lowered below sea level. Nordic
quaternary
As the ice caps disappear, the Earth's crust slowly rises. This isostasy is still going on today.
(3) The ice age changed the distribution of the global climate zone, and a large number of warm-loving plant and animal species became extinct.
Scholars have put forward various explanations, but no satisfactory answer has been obtained so far. In summary, there are mainly astronomy and
geophysics
Cause theory.
[3]
It mainly considers the relationship between the sun, other planets and the Earth.
The periodic variation of the sun's luminosity affects the Earth's climate. When the sun's luminosity is in a weak change, the amount of radiation decreases, the earth becomes cold, and even an ice age climate occurs.
Milan
Kovic believes that the decrease in the amount of solar radiation during the summer half of the year is a possible factor in causing the ice age to occur.
(2) The periodic change of the earth's equatorial Angle leads to the change of temperature. The declination Angle refers to the Angle between the ecliptic and the celestial equator, and its variation is mainly affected by planetary perturbation. When the declination Angle is large, the difference between winter and summer increases and the annual average solar radiation rate is minimal, which makes the low latitude area in the cold period, which is conducive to the formation of glaciers.
There are many influencing factors, including atmospheric physics and geology.
① The effect of atmospheric transparency. Frequent volcanic activity has filled the atmosphere with volcanic ash and reduced the amount of solar radiation, causing the earth to cool.
2.
Tectonic movement
The impact of... The tectonic movement caused the land rise and fall, land mass displacement and apparent pole movement, changed the distribution and circulation pattern of sea and land, and made the earth cool. The feedback effects of cloud cover, evaporation, and reflection from snow and ice further cooled the Earth and contributed to the ice age.
③ The shielding effect of CO2 in the atmosphere CO2 can prevent or reduce the loss of surface heat. If the CO2 content in the atmosphere increases to 2 to 3 times that of today, the polar temperature will rise by 8 to 9 ° C. If the CO2 content in the atmosphere is reduced by 55 to 60% today, the temperature in the middle latitudes will drop by 4 to 5 ° C. in
Geological time
Volcanic and biological activities cause great changes in CO2 content in the atmosphere. When CO2 shielding is reduced to a certain extent, ice age may occur.
