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During the ice age, the earth's surface was covered on a large scale
glacier
the
Geological time
, also known as
Glacial age
. The only correlation between two ice ages
Warm period
, be called
Interglacial period
.
The earth
There have been many ice ages in history, the most recent being
Quaternary glacial period
.
It was an "ice age" (a time span of tens of millions of years or even 200 to 300 million years), a period of sustained global low temperatures and a large extension of continental ice sheets towards the equator. The period when the Earth's climate was warmer between adjacent ice ages is called the "Great Interglacial". There are four major ice ages in the history of the Earth: the Karoo Glacial Age, the Anddisahara Glacial Age, the Varangir Glacial Age, and the Huron Glacial Age. The periods of alternating warm and cold within an ice age are called ice segments (or sub-glacial periods, ice stages) and interglacial segments (or interglacial stages) respectively. The time scale is tens of thousands of years.
The earth
In more than 4 billion years of history, there have been many significant cooling and cooling, forming ice ages. Especially in
The Precambrian Period
Late,
Carboniferous period
to
Permian period
And the Cenozoic ice ages were continuous
time
interminable
Geological event
It is often referred to as the Great Ice Age. The time scale of the Great Ice Age is at least millions of years. During the Great ice age, there were many large scale
climate
Alternations of cooling and warming and expansion of ice sheet size
flinch
This period of expansion and retreat is called the glacial and interglacial periods.
- Chinese name
- Ice age
- Foreign name
- Ice Age / Glacial period
- Also known as
- Glacial age
- connotative
- The earth Cover on a large scale glacier the Geological time
A cold ice age
In the billions of years of geological history, there have been at least three major glaciations around the world
The Precambrian Period
Late Great Ice Age,
Carboniferous period
- The Permian Great Ice Age and
quaternary
The Great Ice Age. What's left of an area where glaciers were active
moraine
It is the main object of glacier research.
Quaternary glacial period
The moraine layer is the best preserved, the most widely distributed and the most thoroughly studied. In the Quaternary, according to the change of glacier coverage area, it can be divided into several glacial periods and interglacial periods, and the ice sheet area accounts for about 30% and 10% of the land surface area, respectively. However, the degree of glacier development varies greatly between continents, such as Europe
Continental ice sheet
It reached 48° north latitude, while Asia only reached 60° North latitude. Due to climate change with regional differences and
Research method
The division of ice ages varies from place to place. In 1909, A. Punke and E. Bruckner of Germany studied
Alps
Four glacial periods and three interglacial periods are classified and named.
[1]
There are various theories about the cause of the Great Ice Age, but many researchers believe that it may be related to the solar System's cycle in the Milky Way. Some believe that the sun's brightness is the smallest when it moves near the galactic point, so that
planet
Became cold and formed the Great Ice Age on Earth; Some believe that the distribution of matter in the Milky Way galaxy is uneven, and the sun passes through the high-density area of interstellar material, reducing the solar radiation energy and forming the great ice age on Earth.
"Glaciers are the product of climate", this is a popular saying in the field of glaciation. So what is climate a product of? The author says "climate change is
Earth system
The reflection of changes in the atmosphere." The cryosphere is part of the Earth system, so one can say that "part of the climate is a product of glaciers." Of course, the main part of the climate should be
geosphere
(including shell, mantle, nucleus)
product
Because the Earth sphere accounts for 99.9% of the total mass of the Earth system. Glaciers are closely related to climate, and they are also restricted by geospheric changes. People can even say that "glaciers and climate are the products of geospheric changes." The change of the geosphere is also restricted by cosmic factors. After long-term research, the author puts forward the following views: the electromagnetic field of the universe and the magnetic fluid of the earth's core
Coupling action
Could be
Earth surface layer
The root cause of the changes in each system is also the root cause of glacier and climate change.
[2]
Ice Age: About 1 million years ago, the earth entered an ice age, and vast areas were covered with snow and ice, and many species such as
stegodon
,
Tapirus giganteus
And all disappeared, and some species like
Giant panda
,
metasequoia
They only survive in very few areas!
A cold ice age
After the Quaternary glacial period, the period of about 10,000 years ago is called
Post-glacial period
. This period of climate still has a number of low magnitude of cold and warm fluctuations, such as the more obvious cold period appeared during 4000~6000 years ago, so that the global glacier once expanded and advanced, known as
neoglacial
.
The most recent notable small-scale glacial advance occurred between the 13th and 14th centuries and the early 20th century (some documents mainly refer to the 16th and 19th centuries), about
18th century
It reached its peak in the mid-19th century, commonly known as the Little Ice Age.
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.
The astronomical theory of origin 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. Milankovitch believes that a 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 in the theory of geophysical origin, 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 CO in the atmosphere
2
The shielding effect. CO
2
Prevents or reduces heat loss from the surface. If CO in the atmosphere
2
The polar temperature will rise by 8~9℃ if the content increases to 2~3 times that of today. 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 times, volcanic and biological activities have caused CO in the atmosphere
2
The content varies greatly when CO
2
If the shielding effect is reduced to a certain extent, an ice age may occur.
Cenozoic
The previous great ice ages are recognizable because of their age
Glacial remains
Scattered and incomplete, the degree of research is also poor, mostly according to the zone contained in the stratum
Glacial scab
Mixed moraines, chert nodules in shale and bedrock undersides with glacial scratches and so on. The glacial remains of the Cenozoic glaciation are generally intact, especially the late Cenozoic glaciation, for example, the sedimentary continuity is good
Deep sea sedimentary core
It can record the changes of global climate and environment more completely. Since the 1970s, scholars in various countries have used oxygen
isotope
Analysis, radiometric dating and paleomagnetic methods attempt to recover and reconstruct the global climate changes of the late Cenozoic
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
Methods such as paleosol and paleosol are often used as the basis for studying the late Cenozoic environment and the division of ice age.
[3]
A cold ice age
It was the earliest known great ice age on Earth. It is represented by the Gaoganda Formation moraines of the Huron Group in southern Canada and the western Great Lakes region of the United States, whose age is from 27 to 2.35 billion years ago. In addition, in
S.Africa
Western Australia, India are all the products of this ice age. The Great Ice Age lasted about 40 million years.
[4]
A widespread glaciation about 95-615 million years ago. vestigialization
Antarctic continent
Although not yet discovered, it has been preserved in many parts of the world's continents and is mostly separated by non-glacial sedimentary layers, indicating that the ice age was multi-stage. It was first found in Scotland and Norway, and has since been found in China, Australia, Africa,
Greenland
And found in North America. In order to
Norse
It is represented by the moraines of Finnmark in the north. In China, it is the Nantuo moraine with scratches at the bottom of the Sinian system, mainly distributed in
Middle and lower reaches of Yangtze River
Let's wait.
Late Ordovician to early Silurian
The Great Ice Age
. About 460-440 million years ago, it is thought that it may have lasted until the late Devonian period (360 million years ago). Its mixed moraines are found in France, Spain, Canada, South America, North Africa and Novaya Zemlya. Moraine outcrops in North Africa are excellent and several are preserved
Glacial landform
Such as well-preserved ice jam structures, drum humps, serpentine humps and sand wedges.
Occurred in the middle Carboniferous period to
Permian period
An early ice age. At that time, global temperatures generally dropped, forming a large area of ice sheets and glaciers, which lasted for 80 million years, and was the most far-reaching ice age in the history of the Earth. It is found in India, Australia, South America, Africa and the margins of the Antarctic continent. Australia
Yadon
The southern and Tasmania regions were the most glaciated during the Great Ice Age.
It was the most recent major ice age in Earth's history. Make a fresh start
Tertiary period
There were alternating glaciations and interglaciations, which have continued to this day. Ice sheets began to appear in Antarctica as early as the Oligocene,
Miocene Epoch
The middle ice sheet is already large, and it is the first area to enter the ice age. The glacial environment in the early Quaternary period spread all over the world and reached its peak in the middle period, so the late Cenozoic glacial period mainly refers to the Quaternary glacial period. At the time, there were two large ice sheets in the Northern Hemisphere, the Scandinavian ice sheet and North America
Laurentian ice sheet
. The southern boundary of the former reaches 50° N, while the latter reaches near 38° N. In addition, some high mountain areas in the middle and low latitudes also developed
Piedmont glacier
Or a small ice cap. About 8,000 to 10,000 years ago, the global general warming, a large number of glaciers and ice sheets disappeared or shrank, the Earth entered the ice stage. But glaciers and ice sheets on the continents have not completely disappeared.
Quaternary glacial periods are divided as follows:
Division of the world. 1901-1909 in Germany
A. Punk
And E. Bruckner successively published the Alps in the Ice Age (3 volumes), which is based on the northern foothills of the European Alps
Danube
The development of gravel terraces in the upper reaches suggests that there are four glaciations and three interglaciations in the mountain area, which are named Gunz, Mindel, Mindel and Mindel respectively.
Reis
(Riss) and
Tamaki
The (Wurm) Glacial period, the Kunz-Mindur, Mindur Lisi, and Lis-Tamaki interglacial periods. Later, B. Abel and I. Schaefer added the older Donau ice Age and the older Biber ice Age. For decades,
Alps
The ice age system is widely used in many parts of the world and is compared to other parts of the world as a typical ice age model.
The earth has experienced ice ages
Loess is the most widely distributed Pleistocene layer on land. It has been developed since the beginning of the Quaternary and has been deposited almost continuously until today. Due to the preservation of a complete loess-paleosoil sedimentary sequence,
Biological fossil
And climate information, it is the most ideal object to study the continental quaternary environmental changes, but also can and deep sea
Sedimentary facies
Compare. Loess is mostly the sediment of the ice age, distributed in Europe and North America in the periphery of the ancient ice sheet. During the interglacial period when the ice sheet retreated, the climate was wet and developed
Brown soil
An alternate sedimentary profile of loess and brown soil was formed, which recorded the climate cycle between ice and interglacial periods. The sedimentary sequence of loess-forest brown soil in Europe can be divided into several sedimentary cycles and sub-cycles, which can correspond to the series of ice ages in Northern Europe. Loess is widely distributed in China and can be up to 410 meters thick. Studies of the Luochuan section in Shaanxi now show that 11 paleoclimatic groups have been recorded since about 2.4 million years ago, comparable to Europe
Loess deposit
Cycle series comparison. There is a good correspondence between the loess sequence of 900,000 years ago and the oceanic phase 1~23 of 18O.
(2) The division and manifestation of China.
Western China
The division of ice ages in alpine areas has been recognized for the better study of the Himalayas
Mount Everest
Taking the north slope of the peak area as an example, the Quaternary glacial period can be divided into: a. basis
Shishapangma Peak
Early Pleistocene established by an old moraine platform near the North Slope
Shishapangma
The ice Age. b. The Neixiongla glaciation of the Middle Pleistocene based on the glacio-glacial deposits of the Neixiongla Plateau on the west side of Mount Qomolangma. c. In the Rongbuk Valley
Keelung
The ruins of the conglomerate group near the temple and the Rongbu Temple upstream
Terminal moraine
Ridge separation
Late Pleistocene
The early Kilungsi stage and the later Rongbusi stage constitute the late Pleistocene Qomolangma ice Age, and 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
In addition to the Taibai Mountain,
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
Mountains in the middle and lower reaches of the Yangtze River, Guilin in Guangxi, Shennongjia in Hubei,
West mountain of Beijing
There is no reliable evidence of ancient glaciers in the Greater Hinggan Mountains in northeast China. The eastern part of China did not have the water, heat and terrain conditions to develop into mountain glaciers, but it was in a relatively cold period. The eastern part of the ancient glacier remains confirmed by Li Siguang are not of glacial origin, such as
Debris flow
Accumulation mistaken for moraine, etc.; Except the Dali glaciation, the Quaternary glaciation series in eastern China are all lacking in basis.
About 2.4 billion to 2.1 billion years ago - Huron Glaciation
About 850-635 million years ago - the glacial period
About 450 to 420 million years ago - the Ordovician period
About 360 million to 260 million years ago - Carboniferous period
About 2.58 million years ago - Quaternary glacial period
The global impact of the ice age was significant.
1. The presence of large ice sheets has changed
Surface water body
The distribution of... During the Late Cenozoic glaciation, 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.
2, during the ice age, the thickness of the large ice sheet 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, and the basement of the Antarctic continent was dropped below the sea level. In Northern Europe, as the Quaternary ice sheets disappeared, the crust slowly rose. This crust
Balanced motion
It is still going on today.
3. Ice ages changed the distribution of global climate zones, leading to the extinction of a large number of warm-loving plant and animal species.
[5]
Seven great ice Ages
The 1970s was a low temperature period in the northern hemisphere (a high temperature period in the Southern Hemisphere), and a low temperature period with little rain in most parts of China.
Tibetan plateau
Snow cover also decreased. However, due to the regulation of topographic thermal circulation, the precipitation in the high altitude area increased slightly during this period, so the proportion of advancing glaciers increased greatly. This has nothing to do with"
Little Ice Age
The situation is quite similar.
The 1970s were
Earth rotation
The slow segment, yes
sunspot
These characteristics are similar to the "Little Ice Age".
