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36-508: Ares Vallis / ˈ ɛər iː z ˈ v æ l ɪ s / is an outflow channel on Mars , named after the Greek name for Mars: Ares , the god of war; it appears to have been carved by fluids, perhaps water . The valley 'flows' northwest out of the hilly Margaritifer Terra , where the Iani Chaos depression 180 km (110 mi) long and 200 km (120 mi) wide) is connected to

72-594: A different cause. According to Tchepalyga, global warming beginning from about 16,000 BP caused the melting of the Scandinavia Ice Sheet , resulting in massive river discharge that flowed into the Caspian Sea , raising it to as much as 50 metres (160 ft) above normal present-day levels. The Sea of Azov rose so high that it overflowed into the Caspian Sea. The rise was extremely rapid and

108-540: A flattened-out Antarctica with a sheet of water 10 metres (33 ft) deep. That volume was added to the world's oceans in a matter of months. The detailed timing and rates of change after the onset of melting of the great ice-sheets are subjects of continuing study. A theory proposed by Andrey Tchepalyga of the Russian Academy of Sciences dates the flooding of the Black Sea basin to an earlier time and from

144-493: A flood that extended 1,400 km (870 mi) downstream and killed 100,000 people. Postglacial rebound changes the tilt of ground. In lakes, this means that shores sink in the direction farther away from the former maximum depth of ice. When the lake rests against an esker , water pressure increases with the increased depth. The esker may then fail under the load and burst, creating a new outflow. Lake Pielinen in Finland

180-537: A megaflood (Gilbert, 1890) describes this event. The last of the North American proglacial lakes, north of the present Great Lakes, has been designated Glacial Lake Ojibway by geologists. It reached its largest volume around 8,500 years ago, when joined with Lake Agassiz. But its outlet was blocked by the great wall of the glaciers and it drained by tributaries, into the Ottawa and St. Lawrence Rivers far to

216-441: A terrestrial jökulhlaup . However, others have argued for an eolian origin, with them induced by katabatic winds blowing down from the poles. Outburst flood In geomorphology , an outburst flood —a type of megaflood —is a high-magnitude, low-frequency catastrophic flood involving the sudden release of a large quantity of water. During the last deglaciation , numerous glacial lake outburst floods were caused by

252-694: Is an example of this. A rising sea flood, the proposed and much-discussed refilling of the freshwater glacial Black Sea with water from the Aegean , has been described as "a violent rush of salt water into a depressed fresh-water lake in a single catastrophe that has been the inspiration for the flood mythology" (Ryan and Pitman, 1998). The marine incursion, caused by the rising level of the Mediterranean, apparently occurred around 7,600 years ago. It remains an active subject of debate among geologists, with subsequent evidence discovered to both support and refute

288-550: Is in the Oxia Palus quadrangle of Mars. It has been argued that Uzboi , Ladon , Margaritifer and Ares valles, although now separated by large craters, once comprised a single outflow channel, flowing north into Chryse Planitia . The source of this outflow has been suggested as overflow from the Argyre Crater, formerly filled to the brim as a lake by channels (Surius, Dzigai, and Palacopus Valles) draining down from

324-410: Is particularly difficult to distinguish outflow channels from lava channels but the following features have been suggested as at least overprinted by outflow channel floods: Several channels flow either onto the plains of Amazonis and Elysium from the southern highlands , or originate at graben within the plains. This region contains some of the youngest channels. Several outflow channels rise in

360-543: The Channeled Scablands . Lake Bonneville , a pluvial lake , burst catastrophically in the Bonneville Flood about 14,500 years ago, due to its water overflowing and washing away a sill composed of two opposing alluvial fans which had blocked a gorge . Lake Bonneville was not a glacial lake, but glacial age climate change determined the lake level and its overflow. The first scientific report of

396-622: The Strait of Gibraltar into the desiccated Mediterranean basin , following the Messinian salinity crisis during which it repeatedly became dry and re-flooded, dated by consensus to before the emergence of modern humans. The Mediterranean did not dry out during the most recent glacial maximum . Sea level during glacial periods within the Pleistocene is estimated to have dropped only about 110 to 120 metres (361 to 394 ft). In contrast,

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432-623: The Caspian basin could not contain all the floodwater, which flowed from the northwest coastline of the Caspian Sea, through the Kuma-Manych Depression and Kerch Strait into the Black Sea basin. By the end of the Pleistocene this would have raised the level of the Black Sea by some 60 to 70 metres (200 to 230 ft) 20 metres (66 ft) below its present-day level, flooding large areas that were formerly available for settlement or hunting. Tchepalyga suggests this may have formed

468-571: The abundant ice present in the ground. Volcanoes would have released gases that thickened the atmosphere for a temporary period, trapping more sunlight and making it warm enough for liquid water to exist. In this new study, channels were discovered that connected lake basins near Ares Vallis. When one lake filled up, its waters overflowed the banks and carved the channels to a lower area where another lake would form. These lakes would be another place to look for evidence of present or past life . Outflow channel Crater counts indicate that most of

504-662: The areas of the modern lakes, but their drainage sometimes passed south, into the Mississippi system; sometimes into the Arctic, or east into the Atlantic. The most famous of these proglacial lakes was Lake Agassiz . As ice-dam configurations failed, a series of great floods were released from Lake Agassiz, resulting in massive pulses of freshwater added to the world's oceans. The Missoula Floods of Oregon and Washington states were also caused by breaking ice dams, resulting in

540-670: The barrier failed or was overtopped, loosing a catastrophic flood that permanently diverted the Rhine into the English Channel and replacing the "Isthmus of Dover" watershed by a much lower watershed running from East Anglia east then southeast to the Hook of Holland and (as at modern sea level) separated Britain from the continent of Europe; a sonar study of the sea bed of the English Channel published in Nature , July 2007, revealed

576-458: The basis for legends of the great Deluge . The barrier across Bab-el-Mandeb , between Ethiopia and Yemen, seems to have been the source of outbreak flooding similar to that found in the Mediterranean. The Lake Toba event, approximately between 69,000 and 77,000 years ago, caused a massive drop in sea levels , exposing the barrier and enabling modern Homo sapiens to leave Africa via a route other than Sinai. The finding of saline evaporites on

612-453: The basis of their geomorphology, locations and sources, the channels are today generally thought to have been carved by outburst floods (huge, rare, episodic floods of liquid water ), although some authors have made the case for formation by the action of glaciers , lava , or debris flows . Calculations indicate that the volumes of water required to cut such channels at least equal and most likely exceed by several orders of magnitude

648-466: The beginning of Ares Vallis by a 100 km (62 mi) wide transition zone centered on 342.5° East (17.5 West) and 3° North. It then continues through the ancient Xanthe Terra highlands, and ends in a delta -like region of Chryse Planitia . Ares Vallis was the landing site of NASA 's Mars Pathfinder spacecraft, which studied a region of the valley near the border with Chryse in 1997. Ares Vallis

684-522: The case of outburst floods, such floods are typically linked to the collapse of a barrier which formed a lake. They fall in the following classification according to the mechanism responsible: Examples where evidence for large ancient water flows has been documented or is under scrutiny include: An example is the lake overflow that caused one of the worst landslide-related disasters in history on June 10, 1786. A landslide dam on Sichuan's Dadu River , created by an earthquake ten days earlier, burst and caused

720-551: The channels were cut since the early Hesperian , though the age of the features is variable between different regions of Mars. Some outflow channels in the Amazonis and Elysium Planitiae regions have yielded ages of only tens of millions of years, extremely young by the standards of Martian topographic features. The largest, Kasei Vallis , is around 3,500 km (2,200 mi) long, greater than 400 km (250 mi) wide and exceeds 2.5 km (1.6 mi) in depth cut into

756-650: The collapse of either ice sheets or glaciers that formed the dams of proglacial lakes . Examples of older outburst floods are known from the geological past of the Earth and inferred from geomorphological evidence on Mars . Landslides , lahars , and volcanic dams can also block rivers and create lakes, which trigger such floods when the rock or earthen barrier collapses or is eroded. Lakes also form behind glacial moraines or ice dams, which can collapse and create outburst floods. Megafloods are paleofloods (past floods) that involved rates of water flow larger than those in

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792-635: The discovery of unmistakable marks of a megaflood on the English Channel seabed: deeply eroded channels and braided features have left the remnants of streamlined islands among deeply gouged channels where the collapse occurred. A catastrophic flood refilled the Mediterranean Sea 5.3 million years ago, at the beginning of the Zanclean age that ended the Messinian salinity crisis . The flood occurred when Atlantic waters found their way through

828-549: The equator. Although earlier research showed that Mars had a warm and wet early history that has long since dried up, these lakes existed in the Hesperian Epoch, a much earlier period. Using detailed images from NASA's Mars Reconnaissance Orbiter , the researchers speculate that there may have been increased volcanic activity, meteorite impacts or shifts in Mars' orbit during this period to warm Mars' atmosphere enough to melt

864-631: The existence of the flood, while the theory that it is the basis of later flood myths is not proven. Flooding of this area scattered peoples to both sides of the gulf depression. It was an area fed by four rivers. Rose calls it the "Gulf Oasis" which may have been a demographic refuge fed by the Tigris, Euphrates, Karun, and Wadi Batin rivers. It was suggested to be an area of freshwater springs and rivers. In North America , during glacial maximum, there were no Great Lakes as we know them, but "proglacial" (ice-frontage) lakes formed and shifted. They lay in

900-526: The floor of the Hellas basin. It has been argued that Uzboi , Ladon , Margaritifer and Ares Valles, although now separated by large craters, once comprised a single outflow channel flowing north into Chryse Planitia . The source of this outflow has been suggested as overflow from the Argyre crater, formerly filled to the brim as a lake by channels (Surius, Dzigai, and Palacopus Valles) draining down from

936-569: The floor of the Red Sea confirms that this dam has functioned at various periods in the past. Rising sea levels during the Flandrian transgression (and in earlier interglacial periods) suggest that this area may have been subject to outburst flooding. Originally there was an isthmus across the Strait of Dover . During an earlier glacial maximum, the exit from the North Sea was blocked to

972-462: The historical record. They are studied through the sedimentary deposits and the erosional and constructional landforms that individual megafloods have created. Floods that are known to us through historical descriptions are mostly related to meteorological events, such as heavy rains, rapid melting of snowpacks, or combination of these. In the geological past of the Earth, however, geological research has shown that much larger events have occurred. In

1008-476: The list reflects this. Originating structures at the head of the channels, if clear and named, are noted in parentheses and in italics after each entry. Chryse Planitia is a roughly circular volcanic plain east of the Tharsis bulge and its associated volcanic systems. This region contains the most prominent and numerous outflow channels on Mars. The channels flow east or north into the plain. In this region it

1044-554: The north by an ice dam , and the water flowing out of rivers backed up into a vast lake with freshwater glacial melt on the bed of what is now the North Sea. A gently upfolding chalk ridge linking the Weald of Kent and Artois , perhaps some 30 metres (100 feet) higher than the current sea level, contained the glacial lake at the Strait of Dover . At some time, probably around 425,000 years ago and again around 225,000 years later

1080-605: The present discharges of the largest terrestrial rivers, and are probably comparable to the largest floods known to have ever occurred on Earth (e.g., those that cut the Channeled Scablands in North America or those released during the re-flooding of the Mediterranean basin at the end of the Messinian Salinity Crisis ). Such exceptional flow rates and the implied associated volumes of water released could not be sourced by precipitation but rather demand

1116-738: The region west of the Elysium volcanic province and flow northwestward to the Utopia Planitia . As common in the Amazonis and Elysium Planitiae regions, these channels tend to originate in graben. Some of these channels may be influenced by lahars , as indicated by their surface textures and ridged, lobate deposits at their margins and termini. The valleys of Hephaestus Fossae and Hebrus Valles are of extremely unusual form, and although sometimes claimed as outflow channels, are of enigmatic origin. Three valleys flow from east of its rim down onto

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1152-493: The release of water from some long-term store, probably a subsurface aquifer sealed by ice and subsequently breached by meteorite impact or igneous activity . This is a partial list of named channel structures on Mars claimed as outflow channels in the literature, largely following The Surface of Mars by Carr. The channels tend to cluster in certain regions on the Martian surface, often associated with volcanic provinces, and

1188-683: The south pole. If real, the full length of this drainage system would be over 8,000 km (5,000 mi), the longest known drainage path in the Solar System . Under this suggestion, the extant form of the outflow channel Ares Vallis would thus be a remolding of a pre-existing structure. This long path for water flow has been named the * Uzboi-Landon-Morava (ULM) system. Water from this system may have helped to form Ares Vallis. Research, published in January 2010, suggests that Mars had lakes, each around 20 km (12 mi) wide, along parts of

1224-449: The south pole. If real, the full length of this drainage system would be over 8000 km, the longest known drainage path in the solar system. Under this suggestion, the extant form of the outflow channel Ares Vallis would thus be a remolding of a pre-existing structure. The large troughs present in each pole, Chasma Boreale and Chasma Australe , have both been argued to have been formed by meltwater release from beneath polar ice, as in

1260-448: The south. About 8,300 to 7,700 years ago, the melting ice dam over Hudson Bay 's southernmost extension narrowed to the point where pressure and its buoyancy lifted it free, and the ice-dam failed catastrophically. Lake Ojibway's beach terraces show that it was 250 metres (820 ft) above sea level. The volume of Lake Ojibway is commonly estimated to have been about 163,000 km (39,000 cu mi), more than enough water to cover

1296-442: The surrounding plains. The outflow channels contrast with the Martian channel features known as " valley networks ", which much more closely resemble the dendritic planform more typical of terrestrial river drainage basins . Outflow channels tend to be named after the names for Mars in various ancient world languages, or more rarely for major terrestrial rivers. The term outflow channels was introduced in planetology in 1975. On

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