When did Ice Age come out?

    An ice age is a period of colder global temperatures and recurring glacial expansion capable of lasting hundreds of millions of years. Thanks to the efforts of geologist Louis Agassiz and mathematician Milutin Milankovitch, scientists have determined that variations in the Earth’s orbit and shifting plate tectonics spur the waxing and waning of these periods. 

    There have been at least five significant ice ages in Earth’s history, with approximately a dozen epochs of glacial expansion occurring in the past 1 million years. Humans developed significantly during the most recent glaciation period, emerging as the dominant land animal afterward as megafauna such as the wooly mammoth went extinct.

    During an ice age, colder global temperatures lead to recurring glacial expansion across the Earth’s surface. Capable of lasting hundreds of millions of years, these periods are interspersed with regular warmer interglacial intervals in which at least one major ice sheet is present. Earth is currently in the midst of an ice age, as the Antarctic and Greenland ice sheets remain intact despite moderate temperatures.

    These global cooling periods begin when a drop in temperature prevents snow from fully melting in some areas. The bottom layer turns to ice, which becomes a glacier as the weight of accumulated snow causes it to slowly move forward. A cyclical pattern emerges in which the snow and ice traps the Earth’s moisture, fueling the growth of these ice sheets as the sea levels simultaneously drop.

    READ MORE: How Humans Survived the Ice Age

    How an Ice Age Changes Earth

    An ice age causes enormous changes to the Earth’s surface. Glaciers reshape the landscape by picking up rocks and soil and eroding hills during their unstoppable push, their sheer weight depressing the Earth’s crust. As temperatures drop in areas adjacent to these ice cliffs, cold-weather plant life is driven to southern latitudes. 

    Meanwhile, the dramatic drop in sea levels enables rivers to carve out deeper valleys and produce enormous inland lakes, with previously submerged land bridges appearing between continents. Upon retreating during warmer periods, the glaciers leave behind scattered ridges of sediment and fill basins with melted water to create new lakes.

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    Scientists have recorded five significant ice ages throughout the Earth’s history: the Huronian (2.4-2.1 billion years ago), Cryogenian (850-635 million years ago), Andean-Saharan (460-430 mya), Karoo (360-260 mya) and Quaternary (2.6 mya-present). Approximately a dozen major glaciations have occurred over the past 1 million years, the largest of which peaked 650,000 years ago and lasted for 50,000 years. The most recent glaciation period, often known simply as the “Ice Age,” reached peak conditions some 18,000 years ago before giving way to the interglacial Holocene epoch 11,700 years ago.

    At the height of the recent glaciation, the ice grew to more than 12,000 feet thick as sheets spread across Canada, Scandinavia, Russia and South America. Corresponding sea levels plunged more than 400 feet, while global temperatures dipped around 10 degrees Fahrenheit on average and up to 40 degrees in some areas. In North America, the region of the Gulf Coast states was dotted with the pine forests and prairie grasses that are today associated with the northern states and Canada.

    Ice Age Theory Origins

    The origins of ice age theory began hundreds of years ago, when Europeans noted that glaciers in the Alps had shrunk, but its popularization is credited to 19th century Swiss geologist Louis Agassiz. Contradicting the belief that a wide-ranging flood killed off such megafauna as the wooly mammoth, Agassiz pointed to rock striations and sediment piles as evidence of glacier activity from a destructive global winter. Geologists soon found evidence of plant life between glacial sediment, and by the close of the century the theory of multiple global winters had been established.

    A second important figure in the development of these studies was Serbian mathematician Milutin Milankovitch. Seeking to chart the Earth’s temperature from the past 600,000 years, Milankovitch carefully calculated how orbital variations such as eccentricity, precession and axial tilt affected solar radiation levels, publishing his work in the 1941 book Canon of Insolation and the Ice Age Problem. Milankovitch’s findings were corroborated when technological improvements in the 1960s allowed for the analyzation of deep sea ice cores and plankton shells, which helped pinpoint periods of glaciation.

    Along with solar radiation levels, it is believed that global warming and cooling is connected to plate tectonic activity. The shifting of the Earth’s plates creates large-scale changes to continental masses, which impacts ocean and atmospheric currents, and triggers volcanic activity that releases carbon dioxide into the air.

    How Humans Adapted to Ice Age's Harsh Climate

    One significant outcome of the recent ice age was the development of Homo sapiens. Humans adapted to the harsh climate by developing such tools as the bone needle to sew warm clothing, and used the land bridges to spread to new regions. By the start of the warmer Holocene epoch, humans were in position to take advantage of the favorable conditions by developing agricultural and domestication techniques. Meanwhile, the mastodons, saber-toothed cats, giant ground sloths and other megafauna that reigned during the glacial period went extinct by its end.

    The reasons for the disappearance of these giants, from human hunting to disease, are among the ice age mysteries that have yet to be fully explained. Scientists continue to study the evidence of these important periods, both to gain more insight into the Earth’s history and to help determine future climatic events.

    Is Dairy Queen ice cream real ice cream?
    You're not actually eating ice cream when you order a cone "To be categorized as ice cream, the minimum butterfat content must be 10 percent, and our soft-serve has only 5 percent butterfat," DQ writes. It's not ice cream, but it is delicious. more
    How thick was the ice in the last ice age?
    During ice ages, huge masses of slowly moving glacial ice—up to two kilometres (one mile) thick—scoured the land like cosmic bulldozers. At the peak of the last glaciation, about 20 000 years ago, approximately 97% of Canada was covered by ice. more
    Is Hershey's ice cream real ice cream?
    real ice cream. real smiles. With over 125 years of experience, Hershey's ® Ice Cream is known for making top quality, REAL ice cream products. We use less air (called overrun) than other ice cream companies, producing a richer and better tasting ice cream! more
    What kind of ice is hospital ice?
    Flake ice For hospitals, here are the most common types of ice: Flake ice: Also known as hospital ice chips, flake ice is soft and chewable. This is a good choice for a hospital for a few reasons. more
    Is DQ ice cream real ice cream?
    Technically, our soft serve does not qualify to be called ice cream. To be categorized as ice cream, the minimum butterfat content must be ten percent, and our soft serve has only five percent butterfat content. more
    Which is healthier Italian ice or ice cream?
    The lack of gluten, fat, and cholesterol makes Gelu a healthier choice for dessert than ice cream products. It also means that people who have restrictive diets can usually enjoy Gelu. The natural, simple ingredients make it easy on your digestion. more
    What is an ice detector system and ice prevention?
    In some aircraft models, multiple ice detectors are used, and the ice detection system automatically turns on the WAI systems when icing is detected. [ Figure 4] Figure 4. An ice detector alerts the flight crew of icing conditions and, on some aircraft, automatically activates ice protection systems. more
    Is dry ice colder than ice?
    Unlike regular ice, dry ice doesn't melt into a liquid as it warms up. Instead, it converts directly back into its gaseous form in a process known as sublimation. At -109° F, dry ice is also significantly colder than the 32° F surface temperature of regular ice. more
    What ice machine makes Chick-fil-A ice?
    1. GE Profile Opal Countertop Nugget Ice Maker V1. GE's Opal nugget ice maker is our highest-rated overall ice machine for a reason. We have the confidence in this machine that has over 12,500 reviews on Amazon, 4.5 stars, and a capacity to deliver you 24-pounds of perfect nugget ice per day. more
    Is ice water colder than ice?
    Due to the more latent heat absorbed by ice as compare to water at same temperature, ice appears more colder than water. more

    Source: www.history.com

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