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78-512: Prior to establishing a vineyard and winery, the Peterson family cultivated bees in the St. Croix River Valley for 3 generations. The first type of wine produced was mead (honey wine) made from Peterson Honey. To reflect its background in honey production, the official logo of Winehaven consists of an image of a honey bee together with the brand name. Winehaven is among the most awarded wineries in

156-635: A candidate for a canal linking the Mississippi River with the Great Lakes. The US Army Corps of Engineers ultimately concluded in 1913 that such a canal would be "inadvisable, infeasible, and impractical". It was along the banks of the St. Croix, in the milltown of Stillwater , that the state of Minnesota was first proposed in 1848. Significant bridge crossings of the St. Croix River are listed below, ordered from source to mouth. The St. Croix

234-611: A change from low-amplitude glacial cycles with a dominant periodicity of 41,000 years to asymmetric high-amplitude cycles dominated by a periodicity of 100,000 years. However, a 2020 study concluded that ice age terminations might have been influenced by obliquity since the Mid-Pleistocene Transition, which caused stronger summers in the Northern Hemisphere . Glaciation in the Pleistocene

312-555: A combination of outstanding wine quality, vigor, disease resistance, and cold hardiness.” The Chisago grape is used in a variety of wines, which include a sweet Deer Garden Red, a desert-style Slippery Slope Red Ice Wine and a newer varietal sold under the name Chisago. 45°22′08″N 92°54′08″W  /  45.36878°N 92.90229°W  / 45.36878; -92.90229 St. Croix River (Wisconsin-Minnesota) The St. Croix River ( / ˈ s eɪ n t ˈ k r ɔɪ / SAYNT KROY ; French for 'Holy Cross')

390-707: A deep inner channel, which includes the Dalles , into the Chengwatana surface. This massive flow of meltwater also created the giant potholes of Interstate Park between 10,800 and 10,600 BP calibrated. The Brule outlet was abandoned when Lake Superior Lobe retreated from the Keweenaw Peninsula and opened lower eastward draining outlets. This caused the Duluth level to drop abruptly to post-Duluth levels and water to cease flowing into Brule outlet and down

468-574: A deviation from today's annual mean temperature, taken as zero. This sort of graph is based on another isotope ratio versus time. Ratios are converted to a percentage difference from the ratio found in standard mean ocean water (SMOW). The graph in either form appears as a waveform with overtones . One half of a period is a Marine isotopic stage (MIS). It indicates a glacial (below zero) or an interglacial (above zero). Overtones are stadials or interstadials. According to this evidence, Earth experienced 102 MIS stages beginning at about 2.588 Ma BP in

546-421: A few regions had been studied and the names were relatively few. Today the geologists of different nations are taking more of an interest in Pleistocene glaciology. As a consequence, the number of names is expanding rapidly and will continue to expand. Many of the advances and stadials remain unnamed. Also, the terrestrial evidence for some of them has been erased or obscured by larger ones, but evidence remains from

624-578: A team of Russian scientists in collaboration with Princeton University announced that they had brought two female nematodes frozen in permafrost , from around 42,000 years ago, back to life. The two nematodes, at the time, were the oldest confirmed living animals on the planet. The evolution of anatomically modern humans took place during the Pleistocene. At the beginning of the Pleistocene Paranthropus species were still present, as well as early human ancestors, but during

702-613: Is a tributary of the Mississippi River , about 169 mi (272 km) long, in the U.S. states of Wisconsin and Minnesota . The lower 125 mi (201 km) of the river form the border between Wisconsin and Minnesota. The river is a National Scenic Riverway under the protection of the National Park Service . A hydroelectric plant at the Saint Croix Falls Dam supplies power to

780-560: Is a popular recreational river. Common uses include boating , fishing, camping and canoeing . Highways along both sides of the river offer scenic drives punctuated by small towns offering restaurants, shopping (especially antiques , books and gifts ), bed and breakfasts , historical tours and other common tourist activities. Public lands along the St. Croix River include: Pleistocene Epoch The Pleistocene ( / ˈ p l aɪ s t ə ˌ s iː n , - s t oʊ -/ PLY -stə-seen, -⁠stoh- ; referred to colloquially as

858-576: Is another River which falls ... into the Meschasipi ... We named it The River of the Grave , or Mausoleum because the Savages buried there one of their Men ... who was bitten by a Rattlesnake." In the original French, this is translated as "Rivière Tombeaux". Jean-Baptiste-Louis Franquelin 's 1688 map recorded a "Fort St. Croix" on the upper reaches of the river. The name "Rivière de Sainte-Croix"

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936-781: Is estimated that, at maximum glacial extent, 30% of the Earth's surface was covered by ice. In addition, a zone of permafrost stretched southward from the edge of the glacial sheet, a few hundred kilometres in North America , and several hundred in Eurasia . The mean annual temperature at the edge of the ice was −6 °C (21 °F); at the edge of the permafrost, 0 °C (32 °F). Each glacial advance tied up huge volumes of water in continental ice sheets 1,500 to 3,000 metres (4,900–9,800 ft) thick, resulting in temporary sea-level drops of 100 metres (300 ft) or more over

1014-459: Is no systematic correspondence between pluvials to glacials, however. Moreover, regional pluvials do not correspond to each other globally. For example, some have used the term "Riss pluvial" in Egyptian contexts. Any coincidence is an accident of regional factors. Only a few of the names for pluvials in restricted regions have been stratigraphically defined. The sum of transient factors acting at

1092-535: Is now a wayside rest and National Historic Landmark along Minnesota State Highway 95 . The vast white pine forests in the upper valley provided the forest products that built the towns along with Lake St. Croix, Minneapolis , and St. Paul ; the St. Croix along with the forest reserves in the river valleys of the nearby Red Cedar , Chippewa, and Rum provided supplies for the building of Winona, Minnesota , Davenport, Iowa , Rock Island, Illinois , and St. Louis. The lumber industry continued to grow throughout

1170-592: The Ice Age ) is the geological epoch that lasted from c.  2.58 million to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations . Before a change was finally confirmed in 2009 by the International Union of Geological Sciences , the cutoff of the Pleistocene and the preceding Pliocene was regarded as being 1.806 million years Before Present (BP). Publications from earlier years may use either definition of

1248-659: The Alpine ice sheet on the Alps . Scattered domes stretched across Siberia and the Arctic shelf. The northern seas were ice-covered. South of the ice sheets large lakes accumulated because outlets were blocked and the cooler air slowed evaporation. When the Laurentide Ice Sheet retreated, north-central North America was completely covered by Lake Agassiz . Over a hundred basins, now dry or nearly so, were overflowing in

1326-639: The Duluth level and an older and smaller epi-Duluth level . At first, glacial meltwater drained from the epi-Duluth level and a smaller precursor proglacial lake, named Lake Nemadji through the Moose Lake (Portage) outlet into the Kettle River and into the St. Croix River. The flow of glacial meltwater from glacial Lake Nemadji and Lake epi-Duluth during the retreat of the Superior Lobe caused

1404-529: The ICS timescale, the Pleistocene is divided into four stages or ages , the Gelasian , Calabrian , Chibanian (previously the unofficial "Middle Pleistocene"), and Upper Pleistocene (unofficially the "Tarantian"). In addition to these international subdivisions, various regional subdivisions are often used. In 2009 the International Union of Geological Sciences (IUGS) confirmed a change in time period for

1482-657: The Isthmus of Panama , causing a faunal interchange between the two regions and changing ocean circulation patterns, with the onset of glaciation in the Northern Hemisphere occurring around 2.7 million years ago. During the Early Pleistocene (2.58–0.8 Ma), archaic humans of the genus Homo originated in Africa and spread throughout Afro-Eurasia . The end of the Early Pleistocene is marked by

1560-677: The Laurentide Ice Sheet . Charles Lyell introduced the term "Pleistocene" in 1839 to describe strata in Sicily that had at least 70% of their molluscan fauna still living today. This distinguished it from the older Pliocene Epoch , which Lyell had originally thought to be the youngest fossil rock layer. He constructed the name "Pleistocene" ('most new' or 'newest') from the Greek πλεῖστος ( pleīstos ) 'most' and καινός ( kainós ( Latinized as cænus ) 'new'). This contrasts with

1638-615: The Mid-Pleistocene Transition , with the cyclicity of glacial cycles changing from 41,000-year cycles to asymmetric 100,000-year cycles, making the climate variation more extreme. The Late Pleistocene witnessed the spread of modern humans outside of Africa as well as the extinction of all other human species. Humans also spread to the Australian continent and the Americas for the first time, co-incident with

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1716-613: The Minneapolis–Saint Paul metropolitan area. The St. Croix River rises in the northwestern corner of Wisconsin, out of Upper St. Croix Lake in Douglas County , near Solon Springs , approximately 20 miles (32 km) south of Lake Superior . It flows south to Gordon , then southwest. It is joined by the Namekagon River in northern Burnett County , where it becomes significantly wider. A few miles downstream

1794-633: The Ouasisacadeba , a French representation of the Dakota name for the St. Croix River. On the 1778 Mitchell Map , the river is simply titled "Ouadeba", which represents the Dakota watpá meaning "river". The upper portion of the river—originally called the north branch of the St. Croix River—was known to the Ojibwa as Manoominikeshiinh-ziibi (Ricing- Rail River). Downstream of its confluence with

1872-597: The Prairie du Chien Line in the south, Mississippi River in the west, St. Croix and Chippewa River watersheds in the north, and a 25-mile parallel east of the Wisconsin River in the east. This opened the region to logging. The river was important to the transportation of lumber downstream, from the areas where it was being cut to the sawmills that processed it. During the 1840s, important sawmills were located at St. Croix Falls and Marine on St. Croix , but as

1950-662: The Ruwenzori Range in east and central Africa were larger. Glaciers existed in the mountains of Ethiopia and to the west in the Atlas Mountains . In the northern hemisphere, many glaciers fused into one. The Cordilleran Ice Sheet covered the North American northwest; the east was covered by the Laurentide . The Fenno-Scandian ice sheet rested on northern Europe , including much of Great Britain;

2028-504: The St. Croix Flowage , 15 miles (24 km) downstream from its source, as well as the Namekagon River , are protected as the St. Croix National Scenic Riverway. The free-flowing nature of the river is interrupted only by the hydroelectric Saint Croix Falls Dam operated by the Northern States Power Company at St. Croix Falls, Wisconsin . The lower 27 miles (43 km) below the dam, including both sides of

2106-477: The last glacial period ended about 10,000 years ago. Over 11 major glacial events have been identified, as well as many minor glacial events. A major glacial event is a general glacial excursion, termed a "glacial." Glacials are separated by "interglacials". During a glacial, the glacier experiences minor advances and retreats. The minor excursion is a "stadial"; times between stadials are "interstadials". These events are defined differently in different regions of

2184-599: The woolly rhinoceros , various giraffids , such as the Sivatherium ; ground sloths , Irish elk , cave lions , cave bears , Gomphotheres , American lions , dire wolves , and short-faced bears , began late in the Pleistocene and continued into the Holocene. Neanderthals also became extinct during this period. At the end of the last ice age, cold-blooded animals, smaller mammals like wood mice , migratory birds, and swifter animals like whitetail deer had replaced

2262-497: The 1850s progressed Stillwater became the primary lumber destination. During this time the population of Stillwater boomed, several additional sawmills were opened, and the town saw an influx of capital, primarily from lumber companies based downriver in St. Louis, Missouri . In 1856 construction began on a booming site two miles north of Stillwater, which was used to store and sort the lumber floating downstream and remained in operation for over fifty years. The St. Croix Boom Site

2340-569: The Early Pleistocene Gelasian . Early Pleistocene stages were shallow and frequent. The latest were the most intense and most widely spaced. By convention, stages are numbered from the Holocene, which is MIS1. Glacials receive an even number and interglacials receive an odd number. The first major glacial was MIS2-4 at about 85–11 ka BP. The largest glacials were 2, 6, 12, and 16. The warmest interglacials were 1, 5, 9 and 11. For matching of MIS numbers to named stages, see under

2418-409: The Earth's surface is cyclical: climate, ocean currents and other movements, wind currents, temperature, etc. The waveform response comes from the underlying cyclical motions of the planet, which eventually drag all the transients into harmony with them. The repeated glaciations of the Pleistocene were caused by the same factors. The Mid-Pleistocene Transition , approximately one million years ago, saw

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2496-544: The Mid-Continent Rift rendered the middle of North America apart, creating a volcanic zone. The lava spewed forth cooled into hard basalt. That basalt is what today creates the dramatic cliffs around the Interstate State Parks. About 500 million years ago, a shallow sea covered the area, laying down layers of sand and minerals that make up much of the sandstone bluffs now seen along the river. In

2574-576: The Namekagon, the Ojibwa renamed the river as Gichi-ziibi (Big River) or Okijii-ziibi (Pipestem River) At the time of the European settlement of the valley, Dakota and Ojibwe were engaged in a long and deadly war with each other. Consequently, the portion of the river below the confluence with Trade River is called Jiibayaatig-ziibi (Grave-marker River) in the Ojibwe language , reinforcing

2652-635: The National Park Service, construction of the bridge was authorized by amending the Wild and Scenic Rivers Act of 1968 . Light and noise pollution are concerns of those opposed to the bridge, who cites the original act that kept such activity to the south along the Interstate 94 corridor. The St. Croix Crossing bridge was ultimately completed in August 2017. The Wild Rivers Conservancy of

2730-479: The North American west. Lake Bonneville , for example, stood where Great Salt Lake now does. In Eurasia, large lakes developed as a result of the runoff from the glaciers. Rivers were larger, had a more copious flow, and were braided . African lakes were fuller, apparently from decreased evaporation. Deserts, on the other hand, were drier and more extensive. Rainfall was lower because of the decreases in oceanic and other evaporation. It has been estimated that during

2808-639: The Pierce Formation and overlying reddish-brown tills and associated sand and gravel of the River Falls Formation. Any glacial landforms associated with these earlier glacial deposits have been destroyed by erosion. These earlier deposits occur as erosional remnants either capping hills or buried by the latest advance of the Laurentide Ice Sheet over this area during the Last Glacial Maximum . The drainage basin of

2886-434: The Pleistocene to 2.58 Ma, results in the inclusion of all the recent repeated glaciations within the Pleistocene. Radiocarbon dating is considered to be inaccurate beyond around 50,000 years ago. Marine isotope stages (MIS) derived from Oxygen isotopes are often used for giving approximate dates. Pleistocene non-marine sediments are found primarily in fluvial deposits , lakebeds, slope and loess deposits as well as in

2964-496: The Pleistocene's overall climate could be characterised as a continuous El Niño with trade winds in the south Pacific weakening or heading east, warm air rising near Peru , warm water spreading from the west Pacific and the Indian Ocean to the east Pacific, and other El Niño markers. Pleistocene climate was marked by repeated glacial cycles in which continental glaciers pushed to the 40th parallel in some places. It

3042-503: The Pleistocene, changing the start date from 1.806 to 2.588 million years BP, and accepted the base of the Gelasian as the base of the Pleistocene, namely the base of the Monte San Nicola GSSP . The start date has now been rounded down to 2.580 million years BP. The IUGS has yet to approve a type section , Global Boundary Stratotype Section and Point (GSSP), for the upper Pleistocene/Holocene boundary ( i.e.

3120-734: The Pleistocene, the East Antarctic Ice Sheet thinned by at least 500 meters, and that thinning since the Last Glacial Maximum is less than 50 meters and probably started after ca 14 ka. During the 2.5 million years of the Pleistocene, numerous cold phases called glacials ( Quaternary ice age ), or significant advances of continental ice sheets, in Europe and North America, occurred at intervals of approximately 40,000 to 100,000 years. The long glacial periods were separated by more temperate and shorter interglacials which lasted about 10,000–15,000 years. The last cold episode of

3198-411: The Pleistocene, the plates upon which they sit probably having moved no more than 100 km (62 mi) relative to each other since the beginning of the period. In glacial periods, the sea level would drop by up to 120 m (390 ft) lower than today during peak glaciation, exposing large areas of the present continental shelf as dry land. According to Mark Lynas (through collected data),

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3276-548: The St. Croix & Namekagon is a watershed-wide non-profit advocating for conservation throughout the watershed. Founded in 1911 as an all-volunteer citizens group, it has evolved into a staffed, mature nonprofit organization and official "friends group" of the St. Croix National Scenic Riverway. Its mission is to inspire stewardship to forever ensure the rare ecological integrity of the St. Croix and Namekagon Riverway. Father Louis Hennepin wrote in 1683, from information probably provided by Daniel Greysolon, Sieur du Lhut : "There

3354-577: The St. Croix River last deglaciated between about 19,000 and 14,000  BP calibrated (16,000 and 12,000  C uncalibrated). During this time, the Superior Lobe retreated from the maximum extent of the Superior Lobe at the Emerald moraine northeastward to Thompson and Nicherson moraine complex at the edge of the Lake Superior basin. During the retreat of the Superior Lobe, a blanket of reddish-brown tills containing beds of fine sand and silt

3432-582: The St. Croix River. The cessation of water outflow through the Brule outlet disconnected the St. Croix River from the Lake Superior basin and created the northward flowing Bois Brule River . The St. Croix River was one of the original eight rivers to have significant portions placed under protection by the National Wild and Scenic Rivers Act of 1968 . The upper reaches of the river in Wisconsin below

3510-528: The St. Croix meets the boundary between Minnesota and Wisconsin, which it demarcates for another 130 miles (209 km) until its confluence with the Mississippi River . Other major tributaries include the Kettle River , Snake River , and Sunrise River joining from the west, and the Apple River , Willow River , and Kinnickinnic River joining from the east. Just below Stillwater, Minnesota

3588-778: The Upper Midwest, having earned over 100 medals from international competitions in New York, California, Indiana and Minnesota. Included among Winehaven's more notable awards are: Winehaven offers 19 types of wine made from a variety of fruits, honey and grapes , including several grape varieties which have been bred to be winter hardy in Minnesota. One variety of grape, Chisago, was developed by Kevin and Kyle Peterson of Winehaven and patented in 2008. The United States Patent and Trademark Office describes it as, “a new and distinct variety of grapevine designated `Chisago`, which has

3666-706: The appearance of Homo sapiens about 300,000 years ago. Artifacts associated with modern human behavior are unambiguously attested starting 40,000–50,000 years ago. According to mitochondrial timing techniques, modern humans migrated from Africa after the Riss glaciation in the Middle Palaeolithic during the Eemian Stage , spreading all over the ice-free world during the late Pleistocene. A 2005 study posits that humans in this migration interbred with archaic human forms already outside of Africa by

3744-539: The area were Sieur du Lhut and his men in the fall and winter of 1679–1680. For the next eighty years, the area was primarily under French influence, and the fur trade grew throughout the first half of the 18th century, with beaver pelts as the prize trade good. French trade in the upper valley was dominated by the Ojibwe and tied to Lake Superior traders, whereas in the lower valley the Dakota assisted in trading with merchants based out of St. Louis downstream. After

3822-527: The articles for those names. Both marine and continental faunas were essentially modern but with many more large land mammals such as Mammoths , Mastodons , Diprotodons , Smilodons , tigers , lions , Aurochs , short-faced bears , giant sloths , species within Gigantopithecus and others. Isolated landmasses such as Australia , Madagascar , New Zealand and islands in the Pacific saw

3900-566: The earlier "Rivière Tombeaux" name in their language. On Map of the Territories of Michigan and Ouisconsin (1830) by John Farmer, the St. Croix River is shown as the "Chippewa River". However, by 1843, Joseph Nicollet 's Hydrographical Basin of the Upper Mississippi River reinforced the name provided by Franquelin's 1688 map. The river is the result of geologic forces going back 1.1 billion years. At that time,

3978-522: The end of the French and Indian War in 1763, British traders entered the area and grew in numbers and influence with the help of the powerful North West Company . The 1837 Treaty of St. Peters with the Ojibwe was signed at St. Peters (now Mendota) which ceded to the United States government a vast tract of land in what today is north central Wisconsin and central Minnesota, roughly bounded by

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4056-618: The entire surface of the Earth. During interglacial times, such as at present, drowned coastlines were common, mitigated by isostatic or other emergent motion of some regions. The effects of glaciation were global. Antarctica was ice-bound throughout the Pleistocene as well as the preceding Pliocene. The Andes were covered in the south by the Patagonian ice cap. There were glaciers in New Zealand and Tasmania . The current decaying glaciers of Mount Kenya , Mount Kilimanjaro , and

4134-672: The evolution of large birds and even reptiles such as the Elephant bird , moa , Haast's eagle , Quinkana , Megalania and Meiolania . The severe climatic changes during the Ice Age had major impacts on the fauna and flora. With each advance of the ice, large areas of the continents became depopulated, and plants and animals retreating southwards in front of the advancing glacier faced tremendous stress. The most severe stress resulted from drastic climatic changes, reduced living space, and curtailed food supply. A major extinction event of large mammals ( megafauna ), which included mammoths , mastodons , saber-toothed cats , glyptodons ,

4212-444: The extinction of most large-bodied animals in these regions. The aridification and cooling trends of the preceding Neogene were continued in the Pleistocene. The climate was strongly variable depending on the glacial cycle, with the sea levels being up to 120 metres (390 ft) lower than present at peak glaciation, allowing the connection of Asia and North America via Beringia and the covering of most of northern North America by

4290-414: The glacial range, which have their own glacial history depending on latitude, terrain and climate. There is a general correspondence between glacials in different regions. Investigators often interchange the names if the glacial geology of a region is in the process of being defined. However, it is generally incorrect to apply the name of a glacial in one region to another. For most of the 20th century, only

4368-450: The historical terminology was established. Corresponding to the terms glacial and interglacial, the terms pluvial and interpluvial are in use (Latin: pluvia , rain). A pluvial is a warmer period of increased rainfall; an interpluvial is of decreased rainfall. Formerly a pluvial was thought to correspond to a glacial in regions not iced, and in some cases it does. Rainfall is cyclical also. Pluvials and interpluvials are widespread. There

4446-445: The immediately preceding Pliocene ("newer", from πλείων ( pleíōn , "more") and kainós ) and the immediately subsequent Holocene ("wholly new" or "entirely new", from ὅλος ( hólos , "whole") and kainós ) epoch , which extends to the present time. The Pleistocene has been dated from 2.580 million (±0.005) to 11,700 years BP with the end date expressed in radiocarbon years as 10,000 carbon-14 years BP. It covers most of

4524-552: The large amounts of material moved about by glaciers. Less common are cave deposits, travertines and volcanic deposits (lavas, ashes). Pleistocene marine deposits are found primarily in shallow marine basins mostly (but with important exceptions) in areas within a few tens of kilometres of the modern shoreline. In a few geologically active areas such as the Southern California coast, Pleistocene marine deposits may be found at elevations of several hundred metres. The modern continents were essentially at their present positions during

4602-421: The last 20,000 years, glaciers have scraped the landscape and released torrents of meltwater, which carved the St. Croix River's course. The river has been home to people for thousands of years. A bison kill site in May Township, Washington County, Minnesota is believed to be about 4,000 years old. An Oneota village from about 1200 A.D. has been studied by archaeologists. At the time of European arrival in

4680-415: The latest period of repeated glaciation , up to and including the Younger Dryas cold spell. The end of the Younger Dryas has been dated to about 9700 BCE (11,700 calendar years BP). The end of the Younger Dryas is the official start of the current Holocene Epoch . Although it is considered an epoch, the Holocene is not significantly different from previous interglacial intervals within the Pleistocene. In

4758-403: The latter half of the 19th century, with progressively larger spring drives and consequent dangers to navigation on the river above Stillwater. Logs were frequently caught in log jams at the narrow Dalles of the St. Croix River , and in 1883 the blockade was so severe it took almost two months before the flow of logs was re-established. The 1886 jam , described as the "jammedest jam", required

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4836-420: The lower Palaeolithic they disappeared, and the only hominin species found in fossilic records is Homo erectus for much of the Pleistocene. Acheulean lithics appear along with Homo erectus , some 1.8 million years ago, replacing the more primitive Oldowan industry used by A. garhi and by the earliest species of Homo . The Middle Paleolithic saw more varied speciation within Homo , including

4914-478: The megafauna and migrated north. Late Pleistocene bighorn sheep were more slender and had longer legs than their descendants today. Scientists believe that the change in predator fauna after the late Pleistocene extinctions resulted in a change of body shape as the species adapted for increased power rather than speed. The extinctions hardly affected Africa but were especially severe in North America where native horses and camels were wiped out. In July 2018,

4992-419: The period. The end of the Pleistocene corresponds with the end of the last glacial period and also with the end of the Paleolithic age used in archaeology . The name is a combination of Ancient Greek πλεῖστος ( pleîstos ) 'most' and καινός ( kainós ; Latinized as cænus ) 'new'. At the end of the preceding Pliocene, the previously isolated North and South American continents were joined by

5070-428: The rapid entrenchment of the St. Croix River and formation of a strath terrace , known as the Chengwatana surface . As the Superior Lobe retreated, the Duluth level was established when another outlet, the Brule outlet, opened and the Moose Lake outlet was abandoned. The opening of the Brule outlet allowed a massive and sudden outflow of glacial meltwater through the Brule outlet and down St. Croix River and excavation of

5148-417: The ratio of O to O (two isotopes of oxygen ) by mass (measured by a mass spectrometer ) present in the calcite of oceanic core samples is used as a diagnostic of ancient ocean temperature change and therefore of climate change. Cold oceans are richer in O , which is included in the tests of the microorganisms ( foraminifera ) contributing the calcite. A more recent version of

5226-403: The recent period of repeated glaciations. The name Plio-Pleistocene has, in the past, been used to mean the last ice age. Formerly, the boundary between the two epochs was drawn at the time when the foraminiferal species Hyalinea baltica first appeared in the marine section at La Castella, Calabria, Italy. However, the revised definition of the Quaternary , by pushing back the start date of

5304-451: The region, the river valley and the surrounding area was occupied by the semi-nomadic Ojibwe , Dakota and nine other American Indian tribes . The Indians lived mainly on wild rice , fish, and game. By the 18th century, the Ojibwe and Dakota were the two primary tribes that inhabited the area, until around 1745, when the Dakota have driven out from the St. Croix Valley as a result of the Battle of Kathio . The first Europeans to arrive in

5382-411: The river along the Minnesota-Wisconsin border, were protected as part of the Lower St. Croix National Scenic Riverway. This area includes the Dalles of the St. Croix River , a scenic gorge located near Interstate Park , south of St. Croix Falls, Wisconsin . Although the addition of an interstate bridge connected to MN Highway 36 was objected to by residents, nearby communities, conservation groups, and

5460-557: The river widens into Lake St. Croix, and eventually joins the Mississippi River at Prescott, Wisconsin , approximately 20 miles (32 km) southeast of St. Paul, Minnesota . The presence of older glacial deposits within the St. Croix River basin proves that the Laurentide Ice Sheet has repeatedly glaciated this region during the Pleistocene Epoch . Within this region these older deposits consist of gray calcareous tills associated with glaciofluvial yellowish-brown sand and gravel and glacial lacustrine silts and clays of

5538-407: The sampling process makes use of modern glacial ice cores. Although less rich in O than seawater, the snow that fell on the glacier year by year nevertheless contained O and O in a ratio that depended on the mean annual temperature. Temperature and climate change are cyclical when plotted on a graph of temperature versus time. Temperature coordinates are given in the form of

5616-649: The sole factor responsible for the variations in climate since they explain neither the long-term cooling trend over the Plio-Pleistocene nor the millennial variations in the Greenland Ice Cores known as Dansgaard-Oeschger events and Heinrich events. Milankovitch pacing seems to best explain glaciation events with periodicity of 100,000, 40,000, and 20,000 years. Such a pattern seems to fit the information on climate change found in oxygen isotope cores. In oxygen isotope ratio analysis, variations in

5694-421: The study of cyclical climate changes. The glacials in the following tables show historical usages, are a simplification of a much more complex cycle of variation in climate and terrain, and are generally no longer used. These names have been abandoned in favour of numeric data because many of the correlations were found to be either inexact or incorrect and more than four major glacials have been recognised since

5772-648: The upper boundary). The proposed section is the North Greenland Ice Core Project ice core 75° 06' N 42° 18' W. The lower boundary of the Pleistocene Series is formally defined magnetostratigraphically as the base of the Matuyama (C2r) chronozone , isotopic stage 103. Above this point there are notable extinctions of the calcareous nannofossils : Discoaster pentaradiatus and Discoaster surculus . The Pleistocene covers

5850-400: The use of steamboats and dynamite to clear. At its peak in 1890, logging in the St. Croix River valley produced 450,000,000 board feet (1,100,000 m ) of lumber and logs. The lumber industry continued until the last major log drive in 1912 marked the end of the rich white pine forests of the area. In the late 1800s and early 1900s, the St. Croix River competed with the St. Louis River as

5928-543: Was a series of glacials and interglacials, stadials and interstadials, mirroring periodic climate changes. The main factor at work in climate cycling is now believed to be Milankovitch cycles . These are periodic variations in regional and planetary solar radiation reaching the Earth caused by several repeating changes in the Earth's motion. The effects of Milankovitch cycles were enhanced by various positive feedbacks related to increases in atmospheric carbon dioxide concentrations and Earth's albedo. Milankovitch cycles cannot be

6006-428: Was applied to the river sometime in 1688 or 1689, and this more auspicious name supplanted Father Hennepin's earlier designation. On Carte de la Louisiane et du Cours du Mississipi (1718) by Guillaume Delisle and on A Map of North America (1768) by John Blair, the St. Croix River—more specifically what was then known as the east branch of the St. Croix River (known today as the Namekagon River )—is shown as

6084-603: Was left behind by the melting of the retreating ice sheet. During glacial retreat, meltwater drainage from the intermediate St.Croix moraine established the precursor to the St. Croix River. The retreat of the Superior lobe into the Lake Superior basin created small, proglacial lakes . Later, these lakes coalesced to form a large proglacial lake called proglacial Lake Duluth , within the western Superior basin. The multiple lake levels of proglacial Lake Duluth included

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