Archaeology Wordsmith

Results for Quaternary:

Pleistocene: SYNONYMS OR RELATED TERMS: ice age, Ice Age, Oiluvium; Quaternary; Great Ice Age; Pleistocene Epoch
CATEGORY: chronology
DEFINITION: A geochronological division of geological time, an epoch of the Quaternary period following the Pliocene. During the Pleistocene, large areas of the northern hemisphere were covered with ice and there were successive glacial advances and retreats. The Lower Pleistocene began c 1.8 million years ago, the Middle Pleistocene c 730,000 years ago, and the Upper Pleistocene c 127,000 years ago; it ended about 10,000 years ago. Most present-day mammals appeared during the Pleistocene. The onset of the Pleistocene was marked by an increasingly cold climate, by the appearance of Calabrian mollusca and Villafranchian fauna with elephant, ox, and horse species, and by changes in foraminifera. The oldest form of man had evolved by the Early Pleistocene (Australopithecus), and in archaeological terms the cultures classed as Palaeolithic all fall within this period. By the mid-Pleistocene, Homo sapiens evolved in Africa and Europe. Homo sapiens spread to Asia and the Americas before the end of the epoch. There were mass extinctions of large and small fauna during the Pleistocene. In North America more than 30 genera of large mammals became extinct within a span of roughly 2,000 years during the late Pleistocene. Of the many causes that have been proposed by scientists for these faunal extinctions, the two most likely are changing environment with changing climate, and the disruption of the ecological pattern by early humans. The Pleistocene was succeeded by the Holocene or present epoch.
Quaternary: SYNONYMS OR RELATED TERMS: Quaternary era; Quaternary Period; Quaternary System
CATEGORY: chronology
DEFINITION: Major geochronological subdivision which includes the Pleistocene (c 1.8-2.45 million years bp) and Holocene (c 10,000 BC) epochs and marked by the appearance of near-humans and Homo sapiens. It is the second period of the Cenozoic geologic era, following the Tertiary, the youngest of the 11 periods in Earth history. These terms may also be applied to groups of deposits, which are described as the Quaternary 'System' and the Pleistocene or Holocene 'Series'. The base of the Quaternary System is defined by basal deposits that overlie Pliocene deposits. The Quaternary was marked by repeated invasions of vast areas of mid-latitude North America and northwestern Eurasia by ice sheets, the period is frequently referred to as the Great Ice Age.
Anglian: SYNONYMS OR RELATED TERMS: Anglian-Elsterian
CATEGORY: chronology
DEFINITION: Quaternary glacial deposits found in East Anglia, England. Other possibly related and isolated patches exist elsewhere in Britain, but they are older than the extreme range of radiocarbon dating and palaeomagnetism shows them to be younger than 700,000 bp. This period is sometimes equates with the Elster glacial maximum and dated to c 300,000-400,000 years ago. During the Anglian-Elsterian glaciation in Europe a large ice-dammed lake formed in the North Sea, and large overflows from it initiated the cutting of the Dover Straits. In East Anglia, the deposits are stratified below Hoxnian and above Cromerian interglacial deposits and Acheulian and Clactonian artifacts are found in the sediments. Most of the evidence of human activity in Britain and Europe is later than this time. Anglian is more often used to describe the group of deposits or the one glaciation (antepenultimate) of that time.
bear: CATEGORY: fauna
DEFINITION: A large carnivore of the family Ursidae, closely related to the dog (family Canidae) and raccoon (Procyonidae). The bear is the most recently evolved of carnivores and it appears to have diverged from the dog family during the Miocene. It evolved through such forms as the Pliocene Hyaenarctos (of Europe, Asia, and North America), into modern types such as the black and brown bear (Ursus). Today's bears are of three groups: the brown bears, the black bears, and the polar bear. Occasional finds of fossil polar bear bones outside the Arctic Circle are presumably related to the presence of pack ice and ice shelves at the edges of ice sheets during glaciations. Brown bears existed in Europe and Asia during the late Quaternary period. One very large variant evolved in Europe, the 'Cave Bear', whose fossils are quite common in Quaternary cave deposits.
bison: CATEGORY: fauna
DEFINITION: The name of two species of wild oxen, the European bison or wisent and the American bison or buffalo. Only a small number of European bison now exist, bred from zoo specimens, and in a protected state in forest of Lithuania. Two further species, now extinct, inhabited Europe and Great Britain for much of the Quaternary period. The great steppe wisent was present during both interglacials and cold period. The smaller wood wisent, was only present in Europe during interglacials. Sometimes these animals are called aurochs. In North America, a number of species preceded today's bison. One species, popularly called 'buffalo', formerly roamed in vast herds over the interior of the continent, mainly in the Rocky Mountains.
Cenozoic: CATEGORY: chronology
DEFINITION: The most recent geological era in the earth's history, in which mammals came to dominate animal life. The Cenozoic was 66.4 million years ago to the present and began when Asia acquired its present appearance and mammals came to dominate animal life. The most important tectonic event in the Cenozoic history of Asia was its collision with India some 50 million years ago. This collision took place some 1,250 miles farther south of the present location of the line of collision along the Indus-Brahmaputra suture behind the main range of the Himalayas. The Cenozoic includes the Tertiary and Quaternary periods and began about 70 million years ago.
Cromerian: CATEGORY: chronology
DEFINITION: An Interglacial Stage of northern Europe correlated with the Günz-Mindel Interglacial, part of the series of interglacials recognized in Britain: the Pastonian (oldest), Beestonian, and Cromerian. The Cromerian stage is a group of Interglacial deposits of the Quaternary system which are stratified under Anglian glacial deposits and above an extensive sequence of earlier Quaternary deposits. The type site of the stage is at West Runton, Norfolk. In northwest Europe, a group of deposits representing several interglacials and intervening cold stages, and these deposits are stratified below Elster glacial deposits and above a sequence extending back into the Pliocene.
deep sea cores: SYNONYMS OR RELATED TERMS: deep sea core dating, deep-sea cores
CATEGORY: technique
DEFINITION: A technique used in the analysis of data from oceanic sediments in which the material retrieved by the core yields information on temperature changes in the ocean through time. These changes, suggestive of climatic variation, help to chart the progress of glaciation and, since they can be dated, the technique assists in the establishment of a chronology for the Quaternary. The cores, some 5 cm. in diameter and up to 25 m. deep, are extracted from the ocean floor. The sediments they contain have a high percentage of calcium carbonate content made up of the shells of small marine organisms and these sediments build up very slowly, from 10-50 mm per 1000 years, but their sequence is uninterrupted. Since these organisms have different temperature preferences depending on species, the relative abundance of the various species changes as the temperature alters. Variations in the ratio of two oxygen isotopes in the calcium carbonate of these shells give a sensitive indicator of sea temperature at the time the organisms were alive. Through the identification of the species, and by the use of oxygen isotope analysis, a picture can be built up of variations in temperature over the millennia. Since various forms of dating (radiocarbon dating, ionium dating, uranium series dating, palaeomagnetism, protactinium/ionium dating) can be used on the carbonate in the shells, absolute dates can be given to the different levels in the core. Thus dates emerge for glaciations and interglacial periods, which can assist in the age determination of archaeological material found in association with these glacial phases. Problems with the technique are the difficulty of correlating oceanic temperature changes with continental glacial and interglacial phases, and the disturbance by animals living on the ocean bottom. The piston corer was developed in 1947.
environmental archaeology: CATEGORY: branch
DEFINITION: A subfield of archaeology which is the study of the environment in archaeological contexts. It includes not only the study of past flora (pollen analysis, palaeobotany, palaeoethnobotany, archaeobotany), and fauna (archaeozoology), but also that of insects (insect analysis), fish (fish bone analysis), and snail shells (molluscan analysis). All are studied in an attempt to recover the total environment of a past society and to understand man's impact on, and changes to, that environment. It is a field in which interdisciplinary research, involving archaeologists and natural scientists. Many disciplines are involved in this study: climatology, Quaternary geology, soil science, palaeobotany, zoology, and human biology.
eustasy: SYNONYMS OR RELATED TERMS: adj. eustatic
CATEGORY: geology
DEFINITION: Changes in sea level on a global basis, usually as the result of a major event such as the end of a glaciation. In such a case a eustatic rise due to the melting of the glaciers can be expected in a post-glacial period. These sea-level movements can be independent of any change in the height of the land, but isostasy can happen contemporaneously as a result of the same phenomenon. This worldwide alteration in sea level is independent of any isostatic movement of the land. At the end of a glaciation melting of the water previously held in the ice sheets raises sea levels (eustatic rise), and a high level can often be correlated with an interglacial period or with the postglacial phase. Such fluctuations have occurred throughout the Quaternary, due to changes in the extent of ice sheets and thus in the volume of water locked up as ice. The larger the ice sheets, the less water available to the sea, and so sea level is lower during glacials than during interglacials. Evidence exists for a whole series of eustatic sea level fluctuations, but the most widespread is the 'high stand' in c 120,000 bp, just before the start of the last cold stage, when sea levels were between 2-10 meters higher than at the present day. During the maximum extent of the ice-sheets of the last cold stage, eustatic sea level was much lower than that of today. Large areas of continental shelf were exposed, some being occupied by the ice sheets themselves. Recovery of sea level at the end of the last cold stage is relatively well known from deposits in the Netherlands, Scandinavia, and Scotland, but is complicated by isostatic changes. The North Sea and English Channel flooded, separating Britain from the Continent, by about 7000 bp. Ireland became a separate island at about the same time. Scandinavia had a complicated series of different seas and lakes, until a sea similar to today's Baltic became established around 7000 bp. The main factors that influence sea level are global ice volumes, plate tectonics, changes in ocean volumes and dimensions, and the movement of mantle material.
Flandrian: CATEGORY: chronology
DEFINITION: Of or pertaining to the period since the retreat of the ice sheet and the rise of sea-level at the end of the last glaciation in northwestern Europe. The Flandrian can be dated by radiocarbon and ranges from 10,000 bp (the end of the Devensian) up to the present day. These deposits represent the latest Quaternary interglacial stage, equivalent to the Holocene epoch. The Flandrian includes sediments similar to those of previous interglacials, deposits on archaeological sites which contain Mesolithic, Neolithic, Bronze Age, Iron Age, Roman, Dark Age, medieval, and more recent artifacts.
geology: CATEGORY: geology; related field
DEFINITION: The study of the physical, chemical, and biological processes and products of the earth; simply, the study of the history of the earth and an understanding of the time scale over which man developed. Geology's aims overlap considerably with those of archaeology, particularly in the prehistoric periods. For example, work on the stratigraphy of the Quaternary to provide a geological chronology for the study of the reconstruction of environmental changes throughout the Quaternary forms an essential background to all archaeology. The palaeontology of fossil hominids and the other animals that lived at the same time is another area in which geology and archaeology overlap. The geological methods of dating such as radiocarbon, palaeomagnetism, and potassium-argon form the basis of most prehistoric chronologies. Geophysical techniques are used for the location of sites and petrology traces the origins of stone implements and inclusions in pottery.
glaciation: SYNONYMS OR RELATED TERMS: glacial
CATEGORY: chronology; geography
DEFINITION: The process by which land is covered by continental and alpine glacier ice sheets or the period of time during which such covering occurred; several glaciations are required to make up an Ice Age (as the Pleistocene). The land is subject to erosion and deposition by this process, which occurred repeatedly during the Quaternary; the process modifies landscapes and affects the level of ocean basins. These periods of colder weather are also called glacials, and the warmer periods between them interglacials. At the onset of colder weather, water is taken up into the ice-sheets and glaciers, causing a drop in sea level. Landscapes covered by ice can be recognized by the smooth rock surfaces and the U-shaped valleys formed by the ice-sheets and glaciers and the rock rubble carried along in them. As the climate warmed, the glaciers retreated, the ice melted, and the sea-level rose. The ice also deposited various forms of boulder clays, and banks of debris at the sides and ends of glaciers, known as moraines. Beyond the limits of glaciers and ice-sheets, extensive layers of outwash sands and gravels were deposited; where these deposits occur in lakes they are called varves. The periglacial zone around the margin of an ice sheet has permanently frozen subsoil, and is occupied by cold-loving plants and animals. Erosion was mainly brought about by solifluxion. The low temperatures and the constant freezing and thawing also affect the soil; these frost effects are called cryoturbation. Particularly characteristic are ice-wedges, polygonal cracks in the ground frequently recognizable in air photographs. They were caused by the shrinking of the ground at low temperatures and the filling of the cracks with water, which subsequently expanded on freezing to open the crack still further. The last two million years have been marked by a series of such glaciations. Broad correlations between the glaciation schemes in different parts of Europe and North America exist. Four Ice Ages have been figured; in Europe, the First Glaciation was at a climax 550,000 years ago. This gradually gave way to the First Interglacial (Gunz-Mindel) Period lasting about 60,000 years in which warm conditions again prevailed. The Second Glaciation came along with its climax 450,000 years ago, and the Second Interglacial Period (Mindel-Riss) followed, lasting 200,000 years. The Third Glacial Period (Riss) climax 185,000 years ago was relieved by 60,000 years of interglacial warmth. The Fourth (Wurm) and last Ice Age was at its height 72,000 years ago. The term has also commonly been used to describe the periods of generally cold climate which occurred at intervals during the Quaternary period. It is, however, now clear that ice-sheets grew only during parts of these so-called 'glacials' (e.g., the Devensian). For this reason, the term 'cold stage' is preferable.
Holocene: SYNONYMS OR RELATED TERMS: Recent, Postglacial
CATEGORY: chronology
DEFINITION: The present geological epoch, which began some 10,000 (bp) years ago (8300 BC). It falls within the Quaternary period (one of the four main divisions of the earth's history) and followed the Pleistocene Ice Age. The Holocene is marked by rising temperatures throughout the world and the retreat of the ice sheets. During this epoch, agriculture became the common human subsistence practice. During the Holocene, Homo sapiens diversified his tool technology, organized his habitat more efficiently, and adapted his way of life. The Holocene stage/series includes all deposits younger than the top of either the Wisconsinian stage of the Pleistocene Series in North America and the Würm/Weichsel in Europe.
Ice Age/ice age: SYNONYMS OR RELATED TERMS: glaciation; glacial age
CATEGORY: chronology
DEFINITION: A period of intense cold and the expansion of glaciers, resulting in a lower sea level. Such periods of large-scale glaciation may last several million years and drastically reshape surface features of entire continents. In the past, there were many ice ages; 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 (1,600,000 to 10,000 years ago). A lesser, recent glacial stage called the Little Ice Age began in the 16th century and advanced and receded intermittently over three centuries. Its maximum development was reached about 1750, at which time glaciers were more widespread on Earth than at any time since the principal Quaternary Ice Ages. The idea of an ice age in the geological sequence is usually credited to Jean Louis Agassiz, a Swiss naturalist, who suggested it c 1837. Agassiz conceived a worldwide cold period when areas as far apart as North America and Germany had been glaciated.
Illinoian: CATEGORY: chronology
DEFINITION: A glacial stage of the Quaternary in North America, followed by the Sangamon Interglacial and following the Yarmouth. The Illinoian ice sheet covered a small area of southeastern and extreme eastern Iowa, and in so doing it diverted the Mississippi River and created a valley along its western front that can still be seen. It consists mainly of tills, the products of large ice-sheets, and has been split up into three sub-stages, the Liman, Monican, and Jubileean. It is unclear how many cold stages the Illinoian deposits represent, but it may be more than one. The Illinoian Glacial Stage ended with a cool, moist period that gradually became drier and then warmer. The Illinoian has never been dated satisfactorily but it is roughly contemporary with the Riss and Saale Glacial Periods.
interglacial: SYNONYMS OR RELATED TERMS: adj interglacial
CATEGORY: chronology
DEFINITION: A warm period between two glaciations during with little or no glacial ice, warm climate processes, deposits, flora and fauna, and increased soil formation. The ice sheets diminish in area, and the improved climate allows the growth of temperate types of vegetation. The last 10,000 years (the Holocene) is probably an interglacial. During the Quaternary, interglacials have been considerably shorter than glacials.
isostasy: SYNONYMS OR RELATED TERMS: isostatic uplift
CATEGORY: geology
DEFINITION: An alteration in the height of the land relative to the sea; the distribution of mass within the Earth's crust is balanced by large-scale topography. These variations are not necessarily associated with changes in sea-level (eustasy), but a major event such as glaciation can affect both land and sea. The weight of ice sheets can cause a lowering in the height of the land, but a thaw at the end of a glaciation frees the land of this pressure and it rises. Continental crust behaves like a body 'floating' on the denser underlying layers. Loading of one area may cause down-warping of the crust, which is compensated by uplift elsewhere. Removal of the load causes the crust to readjust to its former state. It is a theory that the condition of approximate equilibrium in the outer part of the earth is approximately counterbalanced by a deficiency of density in the material beneath those masses, while deficiency of density in ocean waters is counterbalanced by an excess in density of the material under the oceans. This phenomenon has occurred during the Quaternary, due to the development of large ice-sheets. The enormous weight of ice has caused downwarping of the continental crust beneath. At the ice-sheet margins, there was a compensatory uplift. On melting of the ice-sheets, the crust readjusted by uplift in the areas directly underneath and downwarping at the edges. This process is continuing today, for example in northern Europe.
loess: CATEGORY: geology
DEFINITION: A wind-borne rock dust (very fine sediments, silt) carried from outwash deposits and moraines and laid down as a thick stratum during periglacial conditions in the steppe country surrounding the ice sheets. Wind erosion was widespread in the periglacial zone that surrounded the large Quaternary ice sheets. Material was picked up by the wind from the large expanses of proglacial deposits at the ice sheet margins. Because of its exceptional fertility, areas of loess were chosen for settlement by early agriculturists. In central and eastern Europe, as well as Asia and North America, there are notable concentrations of sites on loess. It provided good grazing for the animals on which Palaeolithic man fed, was rich in nutrients for plants, and was later settled by Neolithic farmers who found it easy to till with primitive equipment. It is an essentially unconsolidated, unstratified calcareous silt; commonly it is homogeneous, permeable, and buff to gray in color, and contains calcareous concretions and fossils. Loess is important archaeologically as soil erosion in these regions during the Holocene caused substantial redeposition of this silt, often burying (deeply) and preserving archaeological sites. In semiarid regions people such as the Pueblo Indians made houses and fortresslike closed edifices from loess-based adobe.
Mindel glaciation: SYNONYMS OR RELATED TERMS: Mindel Glacial; Mindel Glacial Stage
CATEGORY: chronology
DEFINITION: The second major Pleistocene glaciation of Alpine Europe which ended with the onset of the Holsteinian Interglacial. It was the second major Ice Age in the Pleistocene period, shown in Quaternary deposits in the Alps and the valleys of south German rivers. The Mindel consists of moraine and related river terraces of proglacial deposits. The Mindel Glacial Stage is part of the early geologic scheme (c. 1900) that first recognized the importance of multiple episodes of Pleistocene glaciation. The stage, a period of relatively severe climatic conditions and glacial advance, preceded the Mindel-Riss Interglacial and followed the Günz-Mindel Interglacial, both periods of relatively moderate climatic conditions. The Mindel Glacial Stage lasted from about 750,000 to 675,000 years ago. At least two periods of glacial advance, separated by a moderate period, are recognized in the Mindel.
Neogene period: CATEGORY: chronology
DEFINITION: The upper division of the Tertiary system including the Miocene and Pliocene periods; latest of the two divisions of the Cenozoic Era (66.4 million years ago to the present). The Neogene includes the Miocene and Pliocene epochs (23,700,000-1,600,000 years ago) and is considered by some to encompass the time up to the present. The Neogene, which means new born was designated as such to emphasize that the marine and terrestrial fossils found in the strata of this time were more closely related to each other than to those of the preceding period called the Paleogene. The term Neogene is widely used in Europe as a geologic division, but is generally not employed in North America, where the Cenozoic Era is simply divided into the Tertiary Period (66,400,000-1,600,000 years ago) and the Quaternary Period (1,600,000 years ago to the present).
Paleogene: SYNONYMS OR RELATED TERMS: Palaeogene
CATEGORY: chronology
DEFINITION: The lower division of the Tertiary system including the Palaeocene, Eocene, and Oligocene periods. The older of the two stratigraphic divisions of the Cenozoic era (which began about 66.4 million years ago and extends to the present). The Paleogene, whose beginning coincides with that of the Cenozoic era, lasted about 42.7 million years and was followed by the Neogene period. The Paleogene, which means ancient-born includes the Paleocene (Palaeocene), Eocene, and Oligocene epochs. The term Paleogene was devised in Europe to emphasize the similarity of marine fossils found in rocks of the first three Cenozoic epochs, as opposed to the later fossils of the Neogene period. In North America, the terms Paleogene and Neogene are not widely used, and the Cenozoic is divided only into the Tertiary period (c 66.4 million-1.6 million years ago) and the Quaternary period (c 1.6 million years ago to present). Thus, the Paleogene period may also be considered to be roughly equivalent to the first two-thirds of the Tertiary period.
periglacial: CATEGORY: chronology
DEFINITION: A term describing cold-climate processes and landforms, an environment with severe frost in non-glacial conditions and have much ground ice, mass movements, and strong winds. It applies to the region surrounding a glacial area and regions immediately beyond the ice-front during a glaciation. In a periglacial zone, part of the ground is perennially frozen. This so-called permafrost layer is covered by a layer which thaws and freezes seasonally, the active layer. Such seasonal changes give rise to several processes, some of which sort the constituents of the active layer and are collectively known as cryoturbation. A variety of landforms, including involutions, ice wedges, and pingos, are formed in the active layer and permafrost. Hillslopes become mantled with frost-shattered rubble that move downslope during cycles of freezing and thawing. Rivers are usually seasonal in the periglacial zone, and erosion by frost action is dominant. Wind erosion and deposition is often an important factor, and caused the formation of the huge deposits of loess and cover-sands in Europe and Asia. The periglacial zone is of interest because it would have been the environment in which man lived for long periods of time during the Devensian/Weichselian cold stage. During the coldest periods of the Quaternary (the last 1,600,000 years), the periglacial zone was enlarged to approximately twice its present size.
Pleistocene Series: CATEGORY: chronology
DEFINITION: A division of the Quaternary System defined by its deposits. It is a worldwide division of rocks deposited during the Pleistocene Epoch (1,600,000-10,000 years ago). It overlies rocks from the Pliocene Epoch (5.3-1.6 million years ago) and is itself overlain by rocks of the Holocene Series; together these two latter divisions make up the Quaternary System. These deposits contain evidence of humans and their development throughout glacial and interglacial conditions. . By international agreement, the global stratotype section/point for the base of the Pleistocene Series is in the Vrica section in Calabria, Italy. The Pleistocene's boundary with the Pliocene occurs just above the position of the magnetic reversal that marks the Olduvai Normal Polarity Subzone, thus allowing the worldwide correlation of Pleistocene rocks with reference to the magneto-stratigraphic timescale.
Rancho La Brea: SYNONYMS OR RELATED TERMS: La Brea Tar Pits
CATEGORY: site
DEFINITION: Quaternary site (Le Brea Tar Pits) near Los Angeles with very large numbers of vertebrate remains dating c 40,000-11,000BP buried in tar pits (asphalt deposits of ancient tar seeps). The tar pits contain the fossilized skulls and bones of prehistoric animals that became entrapped in the sticky seepage of the pits. The remains of such Pleistocene mammals as imperial mammoth, mastodon, saber-toothed cat, giant ground sloth, and camel have been recovered. There are some artifacts, including manos and wooden spear points.
Recent: SYNONYMS OR RELATED TERMS: Holocene
CATEGORY: chronology
DEFINITION: The epoch of geologic time in the late Quaternary following the Pleistocene; referred to as Holocene in several European countries. It is the present geological epoch, which began some 10,000 (bp) years ago (8300 BC). The Recent epoch is marked by rising temperatures throughout the world and the retreat of the ice sheets. During this epoch, agriculture became the common human subsistence practice. During the Recent epoch, Homo sapiens diversified his tool technology, organized his habitat more efficiently, and adapted his way of life. The Recent stage/series includes all deposits younger than the top of either the Wisconsinian stage of the Pleistocene Series in North America and the Würm/Weichsel in Europe.
rhinoceros: SYNONYMS OR RELATED TERMS: pl rhinoceroses, rhinoceri
CATEGORY: fauna
DEFINITION: Any of five species of large hoofed mammals found in eastern and southern Africa and in tropical Asia. The term rhinoceros is sometimes also applied to other, extinct members of the family Rhinocerotidae. Five species of rhinoceros have survived until recently: the Great Indian rhino (Rhinoceros unicornis), the Javan rhino (R. sondaicus), the Sumatran rhino (Dicerorhinus sumatrensis), the white, or grass rhino (Ceratotherium simum) and the black, or browse rhino (Diceros bicornis). Like the elephant, these species have presumably been restricted both by intensified desertification and the interference of man. The closely related woolly rhinoceros evolved late in the Quaternary period and was adapted to cold, open conditions. It became common across Europe and northern Asia during times of colder climate, but became extinct before 10,000 BC.
Tertiary: CATEGORY: chronology
DEFINITION: The geological period following the Mesozoic (Secondary) era, constituting the first of two periods of the Cenozoic Era, the second being the Quaternary. It comprises the epochs Palaeocene, Eocene, Oligocene, Miocene, and Pliocene. It extended from the end of the Cretaceous to the beginning of the Quaternary, from 66.4-1.6 million years ago. The Miocene and Pliocene epochs were important in Hominid Evolution. Some prefer not to use the term Tertiary and instead divide the interval into two periods, the Paleogene Period (66.4-23.7 mya) and the Neogene Period (23.7-1.6 mya). Most of the existing mountain belts and ranges, notably the Andes, the Rockies, the Alps, the Himalayas, and the Atlas Mountains, were formed either partly or wholly during the Tertiary. The emergence and submergence of land bridges between continents, especially between North and South America, Eurasia and Africa, and Asia and North America, critically affected the migration of faunas and floras. The earliest generally accepted hominid fossils, those of Australopithecus, come from rocks of Pliocene age (5.3-1.6 mya) in eastern Africa.
Weichselian: SYNONYMS OR RELATED TERMS: Weichsel Glaciation; Vistula Glacial Stage
CATEGORY: chronology
DEFINITION: The final glacial advance, c 115,000-10,000 bp, corresponding to the Alpine Würm, American Wisconsinan, and British Devensian. The Weichsel Glacial Stage followed the Eemian Interglacial Stage and marks the last major incursion of Pleistocene continental ice sheets. It is named for the ice sheet of north Germany and other Quaternary glacial deposits in northwest Europe. Most of the Weichselian is within the range of radiocarbon dating. The ice sheets were probably at their maximum size for only a short period, between 30,000-13,000 bp; eight interstadials have been recognized in the Weichselian of northwest Europe. The late Weichsel expansion of the Scandinavian continental ice sheet began about 25,000 years ago; most of the Weichselian sediments over northern Europe are part of this late Weichselian cold period.

Another Dictionary Search