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86-529: The Great Black Swamp (also known simply as the Black Swamp ) was a glacially fed wetland in northwest Ohio and northeast Indiana , United States, that existed from the end of the Wisconsin glaciation until the late 19th century. Comprising extensive swamps and marshes , with some higher, drier ground interspersed, it occupied what was formerly the southwestern part of proglacial Lake Maumee ,

172-573: A Holocene precursor to Lake Erie . The area was about 25 miles (40 km) wide (north to south) and 100 miles (160 km) long, covering an estimated 1,500 square miles (4,000 km). Gradually drained and settled in the second half of the 19th century, it is now highly productive farmland. However, this development has been detrimental to the ecosystem as a result of agricultural runoff . This runoff, in turn, has contributed to frequent toxic algal blooms in Lake Erie. The land once covered by

258-424: A cirque landform (alternatively known as a corrie or as a cwm ) – a typically armchair-shaped geological feature (such as a depression between mountains enclosed by arêtes ) – which collects and compresses through gravity the snow that falls into it. This snow accumulates and the weight of the snow falling above compacts it, forming névé (granular snow). Further crushing of the individual snowflakes and squeezing

344-408: A city in 1901. The village was named after Bowling Green, Kentucky , by a retired postal worker who had once delivered mail there. In 1868 Bowling Green was designated as the county seat, succeeding Perrysburg. With the discovery of oil in the area in the late 19th and early 20th century, Bowling Green enjoyed a boom to its economy. The results of wealth generated at the time can still be seen in

430-522: A glacier is usually assessed by determining the glacier mass balance or observing terminus behavior. Healthy glaciers have large accumulation zones, more than 60% of their area is snow-covered at the end of the melt season, and they have a terminus with a vigorous flow. Following the Little Ice Age 's end around 1850, glaciers around the Earth have retreated substantially . A slight cooling led to

516-601: A glacier may flow into a body of water, it forms only on land and is distinct from the much thinner sea ice and lake ice that form on the surface of bodies of water. On Earth, 99% of glacial ice is contained within vast ice sheets (also known as "continental glaciers") in the polar regions , but glaciers may be found in mountain ranges on every continent other than the Australian mainland, including Oceania's high-latitude oceanic island countries such as New Zealand . Between latitudes 35°N and 35°S, glaciers occur only in

602-411: A glacier via moulins . Streams within or beneath a glacier flow in englacial or sub-glacial tunnels. These tunnels sometimes reemerge at the glacier's surface. Most of the important processes controlling glacial motion occur in the ice-bed contact—even though it is only a few meters thick. The bed's temperature, roughness and softness define basal shear stress, which in turn defines whether movement of

688-408: A kilometer per year. Eventually, the ice will be surging fast enough that it begins to thin, as accumulation cannot keep up with the transport. This thinning will increase the conductive heat loss, slowing the glacier and causing freezing. This freezing will slow the glacier further, often until it is stationary, whence the cycle can begin again. The flow of water under the glacial surface can have

774-404: A large effect on the motion of the glacier itself. Subglacial lakes contain significant amounts of water, which can move fast: cubic kilometers can be transported between lakes over the course of a couple of years. This motion is thought to occur in two main modes: pipe flow involves liquid water moving through pipe-like conduits, like a sub-glacial river; sheet flow involves motion of water in

860-448: A local drainage tile industry are thought to have contributed greatly to drainage and settlement. During the second half of the 20th century, efforts were undertaken to preserve and restore portions of the swamp to its pre-settlement state (e.g. Limberlost Swamp ) After the excessive spread of harmful algal blooms in nearby western Lake Erie returned in 2011 and every year since then, there has been renewed interest in restoring wetlands in

946-460: A lower heat conductance, meaning that the basal temperature is also likely to be higher. Bed temperature tends to vary in a cyclic fashion. A cool bed has a high strength, reducing the speed of the glacier. This increases the rate of accumulation, since newly fallen snow is not transported away. Consequently, the glacier thickens, with three consequences: firstly, the bed is better insulated, allowing greater retention of geothermal heat. Secondly,

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1032-488: A thin layer. A switch between the two flow conditions may be associated with surging behavior. Indeed, the loss of sub-glacial water supply has been linked with the shut-down of ice movement in the Kamb ice stream. The subglacial motion of water is expressed in the surface topography of ice sheets, which slump down into vacated subglacial lakes. The speed of glacial displacement is partly determined by friction . Friction makes

1118-410: A tremendous impact as the iceberg strikes the water. Tidewater glaciers undergo centuries-long cycles of advance and retreat that are much less affected by climate change than other glaciers. Thermally, a temperate glacier is at a melting point throughout the year, from its surface to its base. The ice of a polar glacier is always below the freezing threshold from the surface to its base, although

1204-468: Is a persistent body of dense ice that is constantly moving downhill under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries . It acquires distinguishing features, such as crevasses and seracs , as it slowly flows and deforms under stresses induced by its weight. As it moves, it abrades rock and debris from its substrate to create landforms such as cirques , moraines , or fjords . Although

1290-456: Is above or at freezing at the interface and is able to slide at this contact. This contrast is thought to a large extent to govern the ability of a glacier to effectively erode its bed , as sliding ice promotes plucking at rock from the surface below. Glaciers which are partly cold-based and partly warm-based are known as polythermal . Glaciers form where the accumulation of snow and ice exceeds ablation . A glacier usually originates from

1376-407: Is affected by factors such as slope, ice thickness, snowfall, longitudinal confinement, basal temperature, meltwater production, and bed hardness. A few glaciers have periods of very rapid advancement called surges . These glaciers exhibit normal movement until suddenly they accelerate, then return to their previous movement state. These surges may be caused by the failure of the underlying bedrock,

1462-411: Is because these peaks are located near or in the hyperarid Atacama Desert . Glaciers erode terrain through two principal processes: plucking and abrasion . As glaciers flow over bedrock, they soften and lift blocks of rock into the ice. This process, called plucking, is caused by subglacial water that penetrates fractures in the bedrock and subsequently freezes and expands. This expansion causes

1548-406: Is by basal sliding, where meltwater forms between the ice and the bed itself. Whether a bed is hard or soft depends on the porosity and pore pressure; higher porosity decreases the sediment strength (thus increases the shear stress τ B ). Porosity may vary through a range of methods. Bed softness may vary in space or time, and changes dramatically from glacier to glacier. An important factor

1634-434: Is called glaciology . Glaciers are important components of the global cryosphere . Glaciers are categorized by their morphology, thermal characteristics, and behavior. Alpine glaciers form on the crests and slopes of mountains. A glacier that fills a valley is called a valley glacier , or alternatively, an alpine glacier or mountain glacier . A large body of glacial ice astride a mountain, mountain range, or volcano

1720-416: Is called rock flour and is made up of rock grains between 0.002 and 0.00625 mm in size. Abrasion leads to steeper valley walls and mountain slopes in alpine settings, which can cause avalanches and rock slides, which add even more material to the glacier. Glacial abrasion is commonly characterized by glacial striations . Glaciers produce these when they contain large boulders that carve long scratches in

1806-647: Is higher, and the mountains above 5,000 m (16,400 ft) usually have permanent snow. Even at high latitudes, glacier formation is not inevitable. Areas of the Arctic , such as Banks Island , and the McMurdo Dry Valleys in Antarctica are considered polar deserts where glaciers cannot form because they receive little snowfall despite the bitter cold. Cold air, unlike warm air, is unable to transport much water vapor. Even during glacial periods of

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1892-561: Is known as the known as the CSX 8888 incident . It traveled more than 65 miles south of Toledo before being stopped by a veteran railroad worker near Kenton; he jumped into the train while it was moving. No one was hurt and there was no property damage in the incident. According to the United States Census Bureau , the city has a total area of 12.61 square miles (32.66 km ), of which 12.56 square miles (32.53 km )

1978-581: Is land and 0.05 square miles (0.13 km ) is water. Bowling Green is within an area of land that was once the Great Black Swamp which was drained and settled in the 19th century. The nutrient-rich soil makes for highly productive farm land. Bowling Green, Ohio is in the North Western hemisphere at approximately 41.376132°N, -83.623897°W. As of the census of 2010, there were 30,028 people, 11,288 households, and 4,675 families living in

2064-545: Is located on the northeast side of the city, along and north of Wooster Street ( Ohio State Route 64 , Ohio State Route 105 ). As of September 2020, it has 20,232 students. Bowling Green has the main branch of the Wood County District Public Library. A public demand response bus service is operated by the city through B.G. Transit. Bowling Green State University offers shuttle services via its own buses with routes throughout campus and

2150-897: Is termed an ice cap or ice field . Ice caps have an area less than 50,000 km (19,000 sq mi) by definition. Glacial bodies larger than 50,000 km (19,000 sq mi) are called ice sheets or continental glaciers . Several kilometers deep, they obscure the underlying topography. Only nunataks protrude from their surfaces. The only extant ice sheets are the two that cover most of Antarctica and Greenland. They contain vast quantities of freshwater, enough that if both melted, global sea levels would rise by over 70 m (230 ft). Portions of an ice sheet or cap that extend into water are called ice shelves ; they tend to be thin with limited slopes and reduced velocities. Narrow, fast-moving sections of an ice sheet are called ice streams . In Antarctica, many ice streams drain into large ice shelves . Some drain directly into

2236-413: Is the region where there is a net loss in glacier mass. The upper part of a glacier, where accumulation exceeds ablation, is called the accumulation zone . The equilibrium line separates the ablation zone and the accumulation zone; it is the contour where the amount of new snow gained by accumulation is equal to the amount of ice lost through ablation. In general, the accumulation zone accounts for 60–70% of

2322-402: Is the underlying geology; glacial speeds tend to differ more when they change bedrock than when the gradient changes. Further, bed roughness can also act to slow glacial motion. The roughness of the bed is a measure of how many boulders and obstacles protrude into the overlying ice. Ice flows around these obstacles by melting under the high pressure on their stoss side ; the resultant meltwater

2408-552: Is then forced into the cavity arising in their lee side , where it re-freezes. As well as affecting the sediment stress, fluid pressure (p w ) can affect the friction between the glacier and the bed. High fluid pressure provides a buoyancy force upwards on the glacier, reducing the friction at its base. The fluid pressure is compared to the ice overburden pressure, p i , given by ρgh. Under fast-flowing ice streams, these two pressures will be approximately equal, with an effective pressure (p i – p w ) of 30 kPa; i.e. all of

2494-993: The Andes , the Himalayas , the Rocky Mountains , the Caucasus , Scandinavian Mountains , and the Alps . Snezhnika glacier in Pirin Mountain, Bulgaria with a latitude of 41°46′09″ N is the southernmost glacial mass in Europe. Mainland Australia currently contains no glaciers, although a small glacier on Mount Kosciuszko was present in the last glacial period . In New Guinea, small, rapidly diminishing, glaciers are located on Puncak Jaya . Africa has glaciers on Mount Kilimanjaro in Tanzania, on Mount Kenya , and in

2580-644: The Faroe and Crozet Islands were completely glaciated. The permanent snow cover necessary for glacier formation is affected by factors such as the degree of slope on the land, amount of snowfall and the winds. Glaciers can be found in all latitudes except from 20° to 27° north and south of the equator where the presence of the descending limb of the Hadley circulation lowers precipitation so much that with high insolation snow lines reach above 6,500 m (21,330 ft). Between 19˚N and 19˚S, however, precipitation

2666-760: The Himalayas , Andes , and a few high mountains in East Africa, Mexico, New Guinea and on Zard-Kuh in Iran. With more than 7,000 known glaciers, Pakistan has more glacial ice than any other country outside the polar regions. Glaciers cover about 10% of Earth's land surface. Continental glaciers cover nearly 13 million km (5 million sq mi) or about 98% of Antarctica 's 13.2 million km (5.1 million sq mi), with an average thickness of ice 2,100 m (7,000 ft). Greenland and Patagonia also have huge expanses of continental glaciers. The volume of glaciers, not including

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2752-562: The Quaternary , Manchuria , lowland Siberia , and central and northern Alaska , though extraordinarily cold, had such light snowfall that glaciers could not form. In addition to the dry, unglaciated polar regions, some mountains and volcanoes in Bolivia, Chile and Argentina are high (4,500 to 6,900 m or 14,800 to 22,600 ft) and cold, but the relative lack of precipitation prevents snow from accumulating into glaciers. This

2838-535: The Rwenzori Mountains . Oceanic islands with glaciers include Iceland, several of the islands off the coast of Norway including Svalbard and Jan Mayen to the far north, New Zealand and the subantarctic islands of Marion , Heard , Grande Terre (Kerguelen) and Bouvet . During glacial periods of the Quaternary, Taiwan , Hawaii on Mauna Kea and Tenerife also had large alpine glaciers, while

2924-454: The 1850s, the states began an organized attempt to drain the swamp for agricultural use and ease of travel. Various projects were undertaken over a 40-year period. Bowling Green, Ohio resident James B. Hill expedited the draining of swampy areas with his Buckeye Traction Ditcher. Hill's ditching machine laid drainage tiles at a record pace. The area was largely drained and settled over the next three decades. The development of railroads and

3010-448: The 1990s and 2000s. In a study using data from January 1993 through October 2005, more events were detected every year since 2002, and twice as many events were recorded in 2005 as there were in any other year. Ogives or Forbes bands are alternating wave crests and valleys that appear as dark and light bands of ice on glacier surfaces. They are linked to seasonal motion of glaciers; the width of one dark and one light band generally equals

3096-481: The Lake Erie shore, and from (roughly) US 6 south to Findlay and North Star, Ohio in Darke County . Near its southern edge at the southwestern corner of present-day Auglaize County , wheeled transportation was impossible during most of the year, and local residents thought the rigors of travel to be unsuitable for anyone except adult men. The vast swamp was a network of forests, wetlands, and grasslands. In

3182-493: The Lake Erie shoreline east of Toledo. Although much of the area to the east, south, and north was settled in the early 19th century, the dense habitat and difficulty of travel through the swamp delayed its development by several decades. A corduroy road (from modern-day Fremont, Ohio , to Perrysburg, Ohio ) was constructed through the Maumee Road Lands in 1825, and was overlaid with gravel in 1838. Travel in

3268-553: The Northwest Ohio region. Metroparks Toledo is another regional leader in wetland restoration, most notably through the creation of Howard Marsh Metropark. This restored wetland converted nearly 1,000 acres (400 ha) of historical agricultural land into a prosperous wetland that now boasts over half of the bird species found throughout Ohio. Pearson Metropark is another example of both a historic, old growth wet forest, paired with sections of restored wetlands. The story of

3354-412: The advance of many alpine glaciers between 1950 and 1985, but since 1985 glacier retreat and mass loss has become larger and increasingly ubiquitous. Glaciers move downhill by the force of gravity and the internal deformation of ice. At the molecular level, ice consists of stacked layers of molecules with relatively weak bonds between layers. When the amount of strain (deformation) is proportional to

3440-427: The age of 18 living with them, 30.7% were married couples living together, 7.5% had a female householder with no husband present, 3.2% had a male householder with no wife present, and 58.6% were non-families. 35.8% of all households were made up of individuals, and 7.2% had someone living alone who was 65 years of age or older. The average household size was 2.16 and the average family size was 2.82. The median age in

3526-400: The age of 18 living with them, 33.2% were married couples living together, 7.5% had a female householder with no husband present, and 56.8% were non-families. 34.3% of all households were people living alone, including 7.0% who were 65 years of age or older. The average household size was 2.21, and the average family size was 2.84. In the city, the population was spread out, with 13.1% under

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3612-461: The age of 18, 46.6% from 18 to 24, 19.5% from 25 to 44, 13.2% from 45 to 64, and 7.6% who were 65 years of age or older. The median age was 22 years. For every 100 females, there were 87.9 males. For every 100 females age 18 and over, there were 85.4 males. The median income for a household in the city was $ 30,599, and the median income for a family was $ 51,804. Males had a median income of $ 33,619 versus $ 25,364 for females. The per capita income for

3698-520: The air from the snow turns it into "glacial ice". This glacial ice will fill the cirque until it "overflows" through a geological weakness or vacancy, such as a gap between two mountains. When the mass of snow and ice reaches sufficient thickness, it begins to move by a combination of surface slope, gravity, and pressure. On steeper slopes, this can occur with as little as 15 m (49 ft) of snow-ice. In temperate glaciers, snow repeatedly freezes and thaws, changing into granular ice called firn . Under

3784-627: The amount of energy being produced by the turbines. The Black Swamp Arts Festival is a free arts and live music festival held the first full weekend after Labor Day. Its mission is to "connect art and the community by presenting an annual arts festival and by promoting the arts in the Bowling Green community." Public elementary schools of the Bowling Green City School District include Kenwood Elementary, Conneaut Elementary and Crim Elementary. Ridge Elementary

3870-430: The amount of melting at surface of the glacier, the faster the ice will flow. Basal sliding is dominant in temperate or warm-based glaciers. The presence of basal meltwater depends on both bed temperature and other factors. For instance, the melting point of water decreases under pressure, meaning that water melts at a lower temperature under thicker glaciers. This acts as a "double whammy", because thicker glaciers have

3956-713: The annual movement of the glacier. Ogives are formed when ice from an icefall is severely broken up, increasing ablation surface area during summer. This creates a swale and space for snow accumulation in the winter, which in turn creates a ridge. Sometimes ogives consist only of undulations or color bands and are described as wave ogives or band ogives. Glaciers are present on every continent and in approximately fifty countries, excluding those (Australia, South Africa) that have glaciers only on distant subantarctic island territories. Extensive glaciers are found in Antarctica, Argentina, Chile, Canada, Pakistan, Alaska, Greenland and Iceland. Mountain glaciers are widespread, especially in

4042-432: The bedrock has frequent fractures on the surface, glacial erosion rates tend to increase as plucking is the main erosive force on the surface; when the bedrock has wide gaps between sporadic fractures, however, abrasion tends to be the dominant erosive form and glacial erosion rates become slow. Glaciers in lower latitudes tend to be much more erosive than glaciers in higher latitudes, because they have more meltwater reaching

4128-445: The bedrock. By mapping the direction of the striations, researchers can determine the direction of the glacier's movement. Similar to striations are chatter marks , lines of crescent-shape depressions in the rock underlying a glacier. They are formed by abrasion when boulders in the glacier are repeatedly caught and released as they are dragged along the bedrock. The rate of glacier erosion varies. Six factors control erosion rate: When

4214-461: The city limits. There are four turbines that are each 257 feet (78 m) tall. These turbines generate up to 7.2 megawatts of power, which is enough to supply electricity for some 3,000 residents. Located about six miles (10 km) from the city, the turbines can be seen for miles and have become a local attraction . At the site of the turbines, a solar-powered kiosk provides information for visitors, including current information on wind speeds and

4300-414: The city was $ 15,032. About 8.0% of families and 25.3% of the population were below the poverty line , including 12.8% of those under age 18 and 4.8% of those age 65 or over. Lubrizol maintains a soap and surfactant production plant in Bowling Green. The Bowling Green plant opened in 1994 and was expanded in 2013. Ohio's first utility-sized wind farm is located along U.S. Route 6 just west of

4386-406: The city was 23.2 years. 12.8% of residents were under the age of 18; 43.2% were between the ages of 18 and 24; 19.5% were from 25 to 44; 15.7% were from 45 to 64; and 8.9% were 65 years of age or older. The gender makeup of the city was 48.0% male and 52.0% female. As of the census of 2000, there were 29,636 people, 10,266 households, and 4,434 families living in the city. The population density

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4472-480: The city. The population density was 2,390.8 inhabitants per square mile (923.1/km ). There were 12,301 housing units at an average density of 979.4 per square mile (378.1/km ). The racial makeup of the city was 87.6% White , 6.4% African American , 0.2% Native American , 2.1% Asian , 1.4% from other races , and 2.2% from two or more races. Hispanic or Latino of any race were 4.8% of the population. There were 11,288 households, of which 18.9% had children under

4558-571: The created ice's density. The word glacier is a loanword from French and goes back, via Franco-Provençal , to the Vulgar Latin glaciārium , derived from the Late Latin glacia , and ultimately Latin glaciēs , meaning "ice". The processes and features caused by or related to glaciers are referred to as glacial. The process of glacier establishment, growth and flow is called glaciation . The corresponding area of study

4644-467: The deep profile of fjords , which can reach a kilometer in depth as ice is topographically steered into them. The extension of fjords inland increases the rate of ice sheet thinning since they are the principal conduits for draining ice sheets. It also makes the ice sheets more sensitive to changes in climate and the ocean. Although evidence in favor of glacial flow was known by the early 19th century, other theories of glacial motion were advanced, such as

4730-483: The deformation to become a plastic flow rather than elastic. Then, the glacier will begin to deform under its own weight and flow across the landscape. According to the Glen–Nye flow law , the relationship between stress and strain, and thus the rate of internal flow, can be modeled as follows: where: The lowest velocities are near the base of the glacier and along valley sides where friction acts against flow, causing

4816-427: The downtown storefronts, and along Wooster Street, where many of the oldest and largest homes were built. A new county courthouse was also constructed in the 1890s. The Neoclassical US post office was erected in 1913. This period was followed by an expansion of the automobile industry . In late 1922 or early 1923, Coats Steam Car moved to the area and hired numerous workers. It eventually went out of business as

4902-490: The drained Black Swamp area. William J. Mitsch (2017) called for the restoration and creation of 150 sq mi (400 km) of treatment wetlands in the former Black Swamp or 10% of the former wetland, as needed to significantly reduce phosphorus inflow by 40% from the polluted Maumee River to Lake Erie. The Black Swamp Conservancy, founded in 1993, has also been involved in preserving former swamplands. They currently protect 17,600 acres (7,100 ha) spread throughout

4988-418: The essentially correct explanation in the 1840s, although it was several decades before it was fully accepted. The top 50 m (160 ft) of a glacier are rigid because they are under low pressure . This upper section is known as the fracture zone and moves mostly as a single unit over the plastic-flowing lower section. When a glacier moves through irregular terrain, cracks called crevasses develop in

5074-685: The first European settlement in 1833 in the Great Black Swamp at Lauber Hill is told in " Out of the Wilderness, History of the Central Mennonite Church ," 1835-1960. O. Grieser and E. Beck, The Dean Hicks Company, Grand Rapids Michigan, 1960. 41°0′N 84°0′W  /  41.000°N 84.000°W  / 41.000; -84.000 Glacier A glacier ( US : / ˈ ɡ l eɪ ʃ ər / ; UK : / ˈ ɡ l æ s i ər , ˈ ɡ l eɪ s i ər / )

5160-475: The fracture zone. Crevasses form because of differences in glacier velocity. If two rigid sections of a glacier move at different speeds or directions, shear forces cause them to break apart, opening a crevasse. Crevasses are seldom more than 46 m (150 ft) deep but, in some cases, can be at least 300 m (1,000 ft) deep. Beneath this point, the plasticity of the ice prevents the formation of cracks. Intersecting crevasses can create isolated peaks in

5246-402: The glacial base and facilitate sediment production and transport under the same moving speed and amount of ice. Material that becomes incorporated in a glacier is typically carried as far as the zone of ablation before being deposited. Glacial deposits are of two distinct types: Bowling Green, Ohio Bowling Green was first settled in 1832, was incorporated as a town in 1855, and became

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5332-453: The glacier to melt, creating a water source that is especially important for plants, animals and human uses when other sources may be scant. However, within high-altitude and Antarctic environments, the seasonal temperature difference is often not sufficient to release meltwater. Since glacial mass is affected by long-term climatic changes, e.g., precipitation , mean temperature , and cloud cover , glacial mass changes are considered among

5418-428: The glacier will be accommodated by motion in the sediments, or if it'll be able to slide. A soft bed, with high porosity and low pore fluid pressure, allows the glacier to move by sediment sliding: the base of the glacier may even remain frozen to the bed, where the underlying sediment slips underneath it like a tube of toothpaste. A hard bed cannot deform in this way; therefore the only way for hard-based glaciers to move

5504-510: The glacier's surface area, more if the glacier calves icebergs. Ice in the accumulation zone is deep enough to exert a downward force that erodes underlying rock. After a glacier melts, it often leaves behind a bowl- or amphitheater-shaped depression that ranges in size from large basins like the Great Lakes to smaller mountain depressions known as cirques . The accumulation zone can be subdivided based on its melt conditions. The health of

5590-619: The ice at the bottom of the glacier move more slowly than ice at the top. In alpine glaciers, friction is also generated at the valley's sidewalls, which slows the edges relative to the center. Mean glacial speed varies greatly but is typically around 1 m (3 ft) per day. There may be no motion in stagnant areas; for example, in parts of Alaska, trees can establish themselves on surface sediment deposits. In other cases, glaciers can move as fast as 20–30 m (70–100 ft) per day, such as in Greenland's Jakobshavn Isbræ . Glacial speed

5676-420: The ice sheets of Antarctica and Greenland, has been estimated at 170,000 km . Glacial ice is the largest reservoir of fresh water on Earth, holding with ice sheets about 69 percent of the world's freshwater. Many glaciers from temperate , alpine and seasonal polar climates store water as ice during the colder seasons and release it later in the form of meltwater as warmer summer temperatures cause

5762-556: The ice to act as a lever that loosens the rock by lifting it. Thus, sediments of all sizes become part of the glacier's load. If a retreating glacier gains enough debris, it may become a rock glacier , like the Timpanogos Glacier in Utah. Abrasion occurs when the ice and its load of rock fragments slide over bedrock and function as sandpaper, smoothing and polishing the bedrock below. The pulverized rock this process produces

5848-488: The ice, called seracs . Crevasses can form in several different ways. Transverse crevasses are transverse to flow and form where steeper slopes cause a glacier to accelerate. Longitudinal crevasses form semi-parallel to flow where a glacier expands laterally. Marginal crevasses form near the edge of the glacier, caused by the reduction in speed caused by friction of the valley walls. Marginal crevasses are largely transverse to flow. Moving glacier ice can sometimes separate from

5934-411: The idea that meltwater, refreezing inside glaciers, caused the glacier to dilate and extend its length. As it became clear that glaciers behaved to some degree as if the ice were a viscous fluid, it was argued that "regelation", or the melting and refreezing of ice at a temperature lowered by the pressure on the ice inside the glacier, was what allowed the ice to deform and flow. James Forbes came up with

6020-418: The increased pressure can facilitate melting. Most importantly, τ D is increased. These factors will combine to accelerate the glacier. As friction increases with the square of velocity, faster motion will greatly increase frictional heating, with ensuing melting – which causes a positive feedback, increasing ice speed to a faster flow rate still: west Antarctic glaciers are known to reach velocities of up to

6106-748: The industry became centralized in Detroit , Michigan . Bank robbers Pretty Boy Floyd and Billy the Killer encountered police in Bowling Green in April 1931. Their armed confrontation resulted in the death of Billy the Killer. During World War II Italian and German prisoners of war were held nearby. They were used to staff the Heinz Tomato Ketchup factory in town. The ketchup factory closed in 1975. A runaway freight train carrying hazardous liquids passed through Bowling Green in 2001, in what

6192-423: The infrared OH stretching mode of the water molecule. (Liquid water appears blue for the same reason. The blue of glacier ice is sometimes misattributed to Rayleigh scattering of bubbles in the ice.) A glacier originates at a location called its glacier head and terminates at its glacier foot, snout, or terminus . Glaciers are broken into zones based on surface snowpack and melt conditions. The ablation zone

6278-619: The lowest, flattest areas, prone to permanent inundation , deciduous swamp forests predominated, characterized especially by species of ash , elm , cottonwood and sycamore . In slightly higher areas with some topographic relief and better drainage, beech , maples , basswood , tuliptree and other more mesic species were dominant. On elevated beach ridges and moraines with good to excessive drainage, more xeric species, especially oak and hickory , were dominant. The area contained non-forested wetlands, particularly marsh and wet prairies , with marshes being particularly extensive along

6364-679: The most deformation. Velocity increases inward toward the center line and upward, as the amount of deformation decreases. The highest flow velocities are found at the surface, representing the sum of the velocities of all the layers below. Because ice can flow faster where it is thicker, the rate of glacier-induced erosion is directly proportional to the thickness of overlying ice. Consequently, pre-glacial low hollows will be deepened and pre-existing topography will be amplified by glacial action, while nunataks , which protrude above ice sheets, barely erode at all – erosion has been estimated as 5 m per 1.2 million years. This explains, for example,

6450-445: The most sensitive indicators of climate change and are a major source of variations in sea level . A large piece of compressed ice, or a glacier, appears blue , as large quantities of water appear blue , because water molecules absorb other colors more efficiently than blue. The other reason for the blue color of glaciers is the lack of air bubbles. Air bubbles, which give a white color to ice, are squeezed out by pressure increasing

6536-725: The pooling of meltwater at the base of the glacier  — perhaps delivered from a supraglacial lake  — or the simple accumulation of mass beyond a critical "tipping point". Temporary rates up to 90 m (300 ft) per day have occurred when increased temperature or overlying pressure caused bottom ice to melt and water to accumulate beneath a glacier. In glaciated areas where the glacier moves faster than one km per year, glacial earthquakes occur. These are large scale earthquakes that have seismic magnitudes as high as 6.1. The number of glacial earthquakes in Greenland peaks every year in July, August, and September and increased rapidly in

6622-410: The pressure of the layers of ice and snow above it, this granular ice fuses into denser firn. Over a period of years, layers of firn undergo further compaction and become glacial ice. Glacier ice is slightly more dense than ice formed from frozen water because glacier ice contains fewer trapped air bubbles. Glacial ice has a distinctive blue tint because it absorbs some red light due to an overtone of

6708-567: The sea, often with an ice tongue , like Mertz Glacier . Tidewater glaciers are glaciers that terminate in the sea, including most glaciers flowing from Greenland, Antarctica, Baffin , Devon , and Ellesmere Islands in Canada, Southeast Alaska , and the Northern and Southern Patagonian Ice Fields . As the ice reaches the sea, pieces break off or calve, forming icebergs . Most tidewater glaciers calve above sea level, which often results in

6794-409: The stagnant ice above, forming a bergschrund . Bergschrunds resemble crevasses but are singular features at a glacier's margins. Crevasses make travel over glaciers hazardous, especially when they are hidden by fragile snow bridges . Below the equilibrium line, glacial meltwater is concentrated in stream channels. Meltwater can pool in proglacial lakes on top of a glacier or descend into the depths of

6880-423: The stress being applied, ice will act as an elastic solid. Ice needs to be at least 30 m (98 ft) thick to even start flowing, but once its thickness exceeds about 50 m (160 ft) (160 ft), stress on the layer above will exceeds the inter-layer binding strength, and then it'll move faster than the layer below. This means that small amounts of stress can result in a large amount of strain, causing

6966-438: The surface snowpack may experience seasonal melting. A subpolar glacier includes both temperate and polar ice, depending on the depth beneath the surface and position along the length of the glacier. In a similar way, the thermal regime of a glacier is often described by its basal temperature. A cold-based glacier is below freezing at the ice-ground interface and is thus frozen to the underlying substrate. A warm-based glacier

7052-568: The swamp lies primarily within the Maumee River and Portage River watersheds in northwest Ohio and northeast Indiana. The boundary was determined primarily by ancient sandy beach ridges formed on the shores of Lakes Maumee and Whittlesey, after glacial retreat several thousand years ago. It stretched roughly from Fort Wayne, Indiana , eastward to the Ottawa National Wildlife Refuge near Port Clinton along

7138-417: The weight of the ice is supported by the underlying water, and the glacier is afloat. Glaciers may also move by basal sliding , where the base of the glacier is lubricated by the presence of liquid water, reducing basal shear stress and allowing the glacier to slide over the terrain on which it sits. Meltwater may be produced by pressure-induced melting, friction or geothermal heat . The more variable

7224-507: The wet season could still take days or even weeks. The impassibility of the swamp was an obstacle during the so-called Toledo War (1835–36); unable to traverse the swamp, the Michigan and Ohio militias never came to battle. Settlement of the region was also inhibited by endemic malaria . The disease was a chronic problem for residents of the region until the area was drained and former mosquito -breeding grounds were dried up. In

7310-484: Was 2,919 inhabitants per square mile (1,127.0/km ). There were 10,667 housing units at an average density of 1,050.6 per square mile (405.6/km ). The racial makeup of the city was 91.84% White , 2.82% African American , 0.21% Native American , 1.83% Asian , 0.02% Pacific Islander , 1.81% from other races , and 1.46% from two or more races. Hispanic or Latino of any race were 3.48% of the population. There were 10,266 households, out of which 20.2% had children under

7396-560: Was closed in 2013 and Milton Elementary was closed in 2011. Two private primary schools, Bowling Green Christian Academy and the Montessori School of Bowling Green, and one parochial, St. Aloysius, also call Bowling Green home. The Bowling Green Early Childhood Learning Center (Montessori) offers kindergarten and Plan, Do and Talk goes up to grade three. Secondary schools include Bowling Green Middle School and Bowling Green Senior High School . Bowling Green State University

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