3. INTRODUCTION
• Ice age, also called glacial age, any geologic period
during which thick ice sheets cover vast areas of
land.
• Such periods of large-scale glaciation may last
several million years and drastically reshape surface
features of entire continents.
• A number of major ice ages have occurred
throughout Earth history.
• The earliest known took place during Precambrian
time dating back more than 570 million years.
• The most recent periods of widespread glaciation
occurred during the Pleistocene Epoch (2.6 million
to 11,700 years ago).
4. PRECAMBRIAN ICE AGE
• Like other, later, ice ages, the Precambrian one was not a single unbroken period of
glaciation, but waxed and waned for about 400 million years before finally giving way
to a warmer time.
• The oldest known glaciation took place 2.9 billion years ago in South Africa during
the Late Archean; the evidence is provided by glacial deposits in sediments of the
Pongola Rift in southern Africa.
• The most extensive early Precambrian glaciation, the Huronian, occurred 2.4 billion
to 2.1 billion years ago during the early Proterozoic. It can be recognized from the
rocks and structures that the glaciers and ice sheets left behind in parts of Western
Australia, Finland, southern Africa, and North America.
• The most extensive occurrences are found in North America, in a belt nearly 3,000
km (1,800 miles) long.
• Most details are known from the Gowganda Formation in Ontario, which contains
glacial deposits that are up to 3,000 metres (9,850 feet) thick and that occupy an area
of about 20,000 square km (7,700 square miles); the entire glacial event may have
covered an area of more than 2.5 million square km (about 965,260 square miles).
5. • Paleomagnetic studies indicate that the Gowganda Formation occurred near
the paleoequator. Similar, roughly contemporaneous glacial deposits can be
found in other parts of the world, suggesting that there was at least one
extensive glaciation during the early Proterozoic.
• The largest glaciation in Earth’s history occurred during the late Proterozoic. It
left its mark almost everywhere. One of the best-described occurrences is in
the Flinders Range of South Australia, where there is a sequence 4 km (2.5
miles) thick of tillites and varved sediments occupying an area of 400 by 500
km (250 by 300 miles).
• Detailed stratigraphy and isotopic dating show that
three worldwide glaciations took place:
1. the Sturtian glaciation (720 million to 660 million years ago)
2. the Varanger-Marinoan ice ages (650 million to about 635 million years
ago), and
3. the Gaskiers glaciation (a 340,000-year glaciation occurring about 580
million years ago).
6. About 700 million years ago, during the Cryogenian glaciation,
runaway glaciers made Earth look like a snowball
7. PERMO-CARBONIFEROUS ICE AGE
• Toward the end of the Carboniferous, and around 290
million years ago, Gondwanda hovered over the south
polar regions, where glacial centers expanded across the
continents, as evidenced by glacial deposits of tillites
along with striations in ancient rocks.
• Thosse heavily grooved by the advancing glaciers
showed lines of ice flow away from the equator and
toward the poles, which is the opposite direction if the
continents were situated where they are today.
• Overall, the southern continents drifted together over
the South Pole, and massive ice sheets radiating
outward from a central point crossed the present
continentall boundaries.
• The Permo-Carboniferous ice sheet is so extensive that it
can fit within a latitude circle of 50 degrees (A.G.Smith
1997).
8. • Today, glacial deposits formed during the Permo-Carboniferous
glaciation (about 300 million years ago) are found in Antarctica, Africa,
South America, India and Australia.
• If the continents haven’t moved, then this would suggest an ice sheet
extended from the south pole to the equator at this time - which is
unlikely as the UK at this time was also close to the equator and has
extensive coal and limestone deposits.
• If the continents of the southern hemisphere are re-assembled near the
south pole, then the Permo-Carboniferous ice sheet assumes a much
more reasonable size.
• More evidence comes from glacial striations – scratches on the bedrock
made by blocks of rock embedded in the ice as the glacier moves.
• These show the direction of the glacier, and suggest the ice flowed from
a single central point.
9. • The lower sequences of the Rangit Gondwana basin are comprised of
massive diamictite with large stromatolitic dolomite boulders and
dropstone embedded in the coarser sandstone which indicate the cold
glaciomarine environment of deposition, whereas upper sequences
consist of repeated alternate beds of sandstone, black shale and coal
seam with a regular interval depicting the fluvial and deltaic environment
of deposition.
• The enrichment of SiO2, Al2O3, TiO2, MnO, MgO, and K2O indicates that
these sediments were mostly derived from felsic rock source areas.
• Chemical Index of Alteration (CIA) and Index of Compositional Variability
(ICV) CaO + Na2O + K2O/Al2O3, and SiO2 vs. (Al2O3 + K2O + Na2O)
values suggest that the sediments maturity and paleoclimatic
environment deposition of the sediments of lower sequences was cold
and semi-humid whereas the deposition of sediments of upper
sequences was warm and humid.
10.
11. PLEISTOCENE ICE AGE
• The growth of large ice sheets, ice caps, and
long valley glaciers was among the most significant
events of the Pleistocene.
• During times of extensive glaciation, more than 45
million square km (roughly 17,400,000 square miles),
or about 30 percent of Earth’s land area, was
covered by glaciers, and portions of the northern
oceans either were frozen over or had extensive ice
shelves.
• In addition to the Antarctic and Greenland ice
sheets, most of the glacial ice was located in the
Northern Hemisphere, where large ice sheets
extended to midlatitude regions.
• The largest was the Laurentide Ice Sheet in North
America.
12. • The other major ice sheet in North America was the Cordilleran Ice Sheet,
which formed in the mountainous region from western Alaska to northern
Washington.
• Glaciers and ice caps were more widespread in other mountainous areas
of the western United States, Mexico, Central America, and Alaska, as well
as on the islands of Arctic Canada where an ice sheet has been postulated.
• Although smaller in size, the Scandinavian Ice Sheet was similar to the
Laurentide in character. At times, it covered most of Great Britain, where it
incorporated several small British ice caps, and extended south across
central Germany and Poland and then northeast across the
northern Russian Plain to the Arctic Ocean.
• To the east in northern Siberia and on the Arctic Shelf of Eurasia, a
number of small ice caps and domes developed in highland areas, and
some of them may have coalesced to form ice sheets on the shallow shelf
areas of the Arctic Ocean. Glaciers and small ice caps formed in
the Alps and in the other high mountains of Europe and Asia.
13. • At the height of the last major glaciation, known as the Last Glacial
Maximum (LGM),18,000 years before the present, ice sheets covered
Chicago, Boston, Detroit, and Cleveland.
14. • Materials including sediments
deposited in the deep sea, ice formed in
massive glaciers, stalactites formed in
caves, wooly mammoths, and other
large mammals, and spores and pollen
of plants, provide evidence for very
large and frequent oscillations in Earth’s
climate that began about 2.5 million
years ago.
• These oscillations involve the repeated
advance and retreat of glaciers in the
Northern Hemisphere. At their peak,
ice-covered the northern parts of North
America, Europe, and Asia, and the
climate fluctuations also caused major
changes in vegetation and animal
habitats, as well as significant changes
in ocean circulation.
The Franz Josef Glacier, South Island New
Zealand. Rocky material is eroded by the glacier
and is called moraine.
15. • Glaciers deposit very diagnostic
landforms and sediments that are often
full of large boulders eroded from wide
swaths of land over which the ice has
traveled.
• More than a century ago, geologists
determined using such evidence that at
the coldest time of the Pleistocene,
glaciers covered Edinburgh, Scotland;
Moscow, Russia; and Detroit and
Chicago in the US.
• In fact, from the glacial deposits alone,
glaciologists had inferred several major
advances and retreats of the two major
ice sheets, the Laurentide in North
America and the Fennoscandian in
A drumlin in southern Germany. This
landform was deposited under an ice sheet
during the last ice age
16. REFRENCES
• INTRODUCTION :- https://www.britannica.com/science/ice-age-geology
• PRECAMBRIAN ICE AGE :https://austhrutime.com/precambrian_ice_age.htm
https://www.britannica.com/science/Precambrian/Paleoclimate
• PERMOCARBONIFEROUS ICE AGE:-
https://austhrutime.com/precambrian_ice_age.htm
https://www.britannica.com/science/Pleistocene-Epoch/Marine-oxygen-isotope-
record
• PLEISTOCENE ICE AGE :- https://www.britannica.com/science/Pleistocene-Epoch
