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Quarternary Period consists of two unequal epochs:
the Pleistocene Epoch, from 1.6 million years ago to 10,000 years ago, and the Holocene Epoch, from 10,000 years ago to the present
in addition to glaciation, the Pleistocene was also a time of tectonic unrest during which what was common
folding, faulting, uplifts, and volcanism
how many warm-cold Pleistocene climatic cycles are recognized
20 warm-cold Pleistocene climatic cycles
how are the Pleistocene climatic cycles recognized
from paleontologic and oxygen isotope data derived from deep-sea cores
how did glaciation occur in North America
several intervals of widespread glaciation, separated by interglacial periods
areas far beyond the ice were affected by Pleistocene glaciation:
climate belts were compressed toward the equator, large pluvial lakes existed in what are now arid regions, and sea level was as much as 130 m lower than at presetn
probably occur as a consequence of the changing positions of tectonic plates
major glacial intervals separated by tens or hundreds of millions of years
two proposed causes for short-term climatic changes are
changes in the amount of solar energy recieved by the Earth and volcanism
mineral resources of the Quaternary are mainly
sand and gravel along with some evaporite minerals such as borax
time of extensive glaciation. at least four of these are recognized in North America, and six or seven are recognized in Europe
time between glacial stages when glaciers cover much less area and global temperatures are warmer than during a glacial stage
theoretical concept of the Earth's crust "floating" on a dense underlying layer; areas of less dense continental crust rise topographically above more dense oceanic crust
Little Ice Age
interval of nearly four centuries (1300 A.D. to the mid- to late 1800s) during which glaciers expanded to their greatest historic extents
explains cyclic variations in climate as a consequence of irregularities in the Earth's rotation and orbit
first of two epochs comprosing the Quaternary Period. commonly called the Ice Age. occrred between 1.6 million and 10,000 years ago
any lake that formed beyond the areas directly affected by glaciation during the Pleistocene as a result of increased precipitation and lower evaporation rates, e.g., Lake Bonneville
identification and statistical analysis of pollen from sedimentary rocks; such analyses provide information about ancient floras and climates
term for a geologic period or system comprising all geologic time or rocks fro the end of the Tertiary to the present; consists of two epochs or series, the Pleistocene and the Recent (Holocene)
North American glacial stages
Wisconsin, Illinoian, Kansan, and Nebraskan; named for the states representing the farthest advace where deposits are well exposed
the three interglacial stages
Sanamon, Yarmouth, and Aftonian; named for localities of well-exposed interglacial soil and other deposits
can be used to detremine oceanic surface temperatures during the Pleistocene
O18 to O16 isotope ratios; identification of planktonic foraminiferal species; coiling ratios of planktonic foraminiferal species; and ocean chemistry
lakes that formed far from glaciers during times of glaciation in what are now dry areas are known as
phenomenon in which the crust sinks and then rises as a result of loading by glaciers followed by melting
formation of land bridges such as the one across the Bering Straits or between Europe and England during the Pleistocene resulted from
a drop in sea level
parameters Milankovitch used to explain the glacial-interglacial episodes of the Pleistocene
the degree to which the orbit departs from a perfect circle; the angle a line perpendicular to the plane of the ecliptic; the precession of the equinoxes
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