Why do advancing glaciers have a steep, cliff-like edge?
543444
They all don't. It depends on the geography of the area of the face. Some glaciers creep along flat ground with little vertical development at the face.\n\nThe steep faces are uusually seen on glaciers at the oceans edge, where a combination of a steep descent from the land to the relatively warmer water causes the glacier face to melt and "cleave", that is, shed large areas of its surface.  Because of the steep descent, the cleaving force is mainly vertical.  You often see pictures of these glaciers taken by folks on cruise ships.\n\nCleaving is aslo called "calving"
863614
This depends a bit on what we call a "mountain range". However;\nThe big ranges (Andes, Himalaya, Alps etc) are all very young, most uplift in the past 30 million years and much in the past 3-5my\nThe mountain belt including the Scandinavian peninsula, the Scottish Highlands, English Lake District and Wales were part of an "Andean" type range about 400my ago.  The Apalachians in the US are actually part of the same chain, "broken off" so to speak.\n\nSome parts of the Scottish Highlands, in the north west, were formed in the core of a much older range, up to 2,500my, but it is debatable whether you can call that a "mountain range".\n\nThe very ancient granites and gneisses (>4,000my) in Canada, Australia, Southern Africa and Greenland were likewise probably part of a mountain building episode, though the Plate Tectonics that formed later mountains probably hadn't kicked in then.  And these days, those areas are mostly rather level and eroded.  The South Africa/Swaziland border where some of these rocks are found is pretty rugged, but whether you could call it a "mountain range" is again debatable.\n\nPart of the problem is that there are ancient rocks within some very young mountain ranges - the rocks are old but the uplift forming the mountains is recent.\n\nIf we call a mountain range a "linear feature of land with steep and rugged terrain significantly higher than the land either side" , and an old range is one that has always been relatively high, not recently pushed up, then we need to find such a feature made of Pre-Cambrian rocks to meet the definition of "oldest mountain range".\n\nOff the top of my head, I'd plump for parts of the Appalachians.  The main range is "only" a few hundred milion years old, but the Pre-Cambrian blocks within were probably standing as elevated mountain blocks when the plate collision forming the range began.  So there has been an elevated upland in that area for perhaps a billion years.
1074888
Actually, the rock face was stronger in  the middle in order to support such a robust figurehead.  Did you ever notice that when\nyou are looking at them, they are looking back?  Kinda freaky !
860120
Glaciers cannot move across entire oceans.  Large continental ice sheets that grow large enough to intersect a coastline sometimes extend into the ocean (see #1 below).  Their base sits on the seafloor, and in some cases can extend hundreds of miles out to sea.  The West Antarctic Ice Sheet is a continental glacier that is 'grounded' below sea level.  It sits on the continental shelf of the Ross Sea.  In the past (several thousands of years ago), it extended all the way to the edge of the continental shelf.\n\nThese glaciers also usually have whats is called an ice shelf.  An ice shelf is an extension of the glacier that floats on the ocean.  Icebergs are a product of bits of the ice shelf breaking off into the ocean.  Ice shelves can extend several hundreds of miles into the ocean (see #2).\n\nValley glaciers in places like Alaska or Greenland also discharge into the ocean.  The ends of these glaciers typically float and extend out into the bay of the valley where the glacier sits.
839668
Here's what I found... \n\n\n\nPhysical Features:\n\nThe main mountain system of the Scandinavian peninsula hardly deserves its name of Kjdlen' (the keel). It may rather be described as a plateau deprived of the appearance of a plateau, being on the one hand grooved by deep valleys, while on the other many salient peaks tower above its average level. Such peaks, during the later Glacial period, stood above the ice-field. Peaks and ridges were formed by the action of small glaciers cutting out each its circular hollow (botn) just as they still work on the remaining snow-fields. But where the power of the main ice-mass was at work, the characteristic rounded forms of base rock are seen, close above the sea along the coast, but even as high as 5000 ft. in some inland localities. The high plateau lies along the W. side of the peninsula, so that except in the S.E. Norway is mountainous throughout. Even the part excepted is hilly, but it partakes of the character of the long eastern or Swedish slope of the peninsula. Beyond the coast line their floors sink far below sea-level, and thus are formed the fjords and the belt of rugged islands which characterize almost the entire seaboard of Norway. Where Norway marches with Russia, a few heights exceed 3000,or even 4000 ft., but the land is not generally of great elevation. But from the point of junction with Swedish territory the mountains increase considerably in height. For a short distance, as far south as Lake Tome, the loftiest points lie within Norwegian territory, such as Jaggevarre (6283 ft.), between Lyngen and Ulfs fjords, and Kiste Fjeld (5653 ft.) farther inland. Thereafter the principal heights lie approximately along the crest-line of the plateau and within Swedish territory. Sulitelma, however (6158 ft.), lies on the frontier. Southward again the higher summits fall to Norway. S. of Boa, Svartisen (" the black ice "), a magnificent snow-field bordering the coast, and feeding many glaciers, culminates at 5246 ft. Thereafter, Okstinderne or Oxtinderne (6273 ft.), and the Store Borge Fjeld (5587 ft.) are the principal elevations as far as 64° N. A little S. of this latitude the so-called Trondhjem depression is well marked right across the central upland, the height of the mountains not often exceeding 4000 ft., while the peaked form characteristic of the heights which rose clear of the glaciers of the later Glacial period is wanting. It is from this point too that Norwegian territory broadens 1 In Norwegian the definite article (when there is no epithet) is added as a suffix to the substantive (masc. and fern. en, neuter et). Geographical terms are similarly suffixed to names, thus Suldalsvandet, the lake Suldal. The commonest geographical terms are: elm, river; vand, lake; fjeld, mountain or highland; o, island; dal, valley; noes, cape; fos, waterfall; brce, glacier; vik, vig, bay; eide, isthmus; fjord. Aa is pronounced aw. \n\nso as to include not only the highest land in the peninsula, but a considerable part of the general E. and S.E. slope. The high plateau broadens and follows the S.W. sweep of the coast. Pursuing it S. the Dovre Fjeld is marked off by the valleys of the rivers Driva and Sundal, Laagen (or Laugen) and Rauma, and the fjords of the coastland of Nordmdre. Here Sneha tta reaches a height of 7615 ft., and the Romsdal (the name under which the Rauma valley is famous among tourists) is flanked by many abrupt jagged peaks up to 6000 ft. high. The valley of the Laagen forms the upper part of Gudbrandsdal. East of this and S.E. of the Dovre is another fjeld, Rondane, in which Hdgronden rises to 6929 ft. South of the Otta valley is Jotunheim or Jdtun Fjeld, a sparsely peopled, in parts almost inaccessible, district, containing the highest mountains in Scandinavia, Galdhiipiggen reaching 8399 ft. On the seaward side of Jotunheim is Jostedalsbra, a great snow-field in which Lodalskaupen reaches a height of 6795 ft. South of Sogne Fjord (61° N.)
442402
The mouth.\nLakes,streams from mountains.The ice from mountains melt,causing tiny streams of water running down the mountain.As it goes along,more water is collected(rain etc.),and it becomes a small river.There are three stages of a river.First,the valley is narrow,second,it gets wider,and third, it is almost flat and very wide.it ends at the sea. \nHope this helps :)
1125378
One thing you notice right away about snow crystals is that they form some elaborate and complex shapes -- often displaying lacy, branching structures.  Where does this complexity come from?  After all, snow crystals are nothing more than ice which has condensed from water vapor.  How does the simple act of water vapor freezing into ice produce such intricate designs? \n   The answers to these questions lie in just how water molecules travel through the air to condense onto a growing snow crystal.   The water molecules have to diffuse through the air to reach the crystal, and this diffusion slows their growth.  The farther water molecules have to diffuse through the air, the longer it takes them to reach the growing crystal.\n   So consider a flat ice surface that is growing in the air.  If a small bump happens to appear on the surface, then the bump sticks out a bit farther than the rest of the crystal.  This means water molecules from afar can reach the bump a bit quicker than they can reach the rest of the crystal, because they don't have to diffuse quite as far.\n   With more water molecules reaching the bump, the bump grows faster.  In a short time, the bump sticks out even farther than it did before, and so it grows even faster.  We call this a branching instability -- small bumps develop into large branches, and bumps on the branches become sidebranches.  Complexity is born.   This instability is a major player in producing the complex shapes of snow crystals. \n   When the branching instability applies itself over and over again to a growing snow crystal, the result is called an ice dendrite.   The word dendrite means "tree-like," and stellar dendrite snow crystals are common.\n   We can change diffusion in the lab and see how dendrites change.  If one grows snow crystals in air below atmospheric pressure, they have fewer branches.   This is because diffusion doesn't limit the growth so much at lower air pressures, so the branching instability is not so strong.  At higher pressures, more branches appear. \n \n   The growth of snow crystals depends on a balance between faceting and branching.  Faceting tends to make simple flat surfaces, while branching tends to make more complex structures.  The interplay between faceting and branching is a delicate one, depending strongly on things like temperature and humidity.  This means snow crystals can grow in many different ways, resulting in the great diversity we see in snow crystal forms.
636880
No, they have ice cores from it that go back 100,000 years. Its edges were a little less icy up to about 600 years ago.
54684
Two ideas: 1. Eroded (continental glaciers form deep valleys)\n                 2. Depressed (see link on isostacy)\n\nMaybe look in your text book.
228826
It's because as the slab descends, it stays fairly cold (because rock doesn't conduct heat very well!), and the pressure increases.  As the pressure increases, certain minerals change their shape to more compact arrangments, typically losing water and other "volatiles" (this is called slab dehydration).  When these volatiles are lost, they move upwards into the overlying "mantle wedge", where they lower the melting point of the rock.  It's from here that magmas arise.  The reason for the 100km or so distance from the zone of subduction is due to the slab "dehydration" not occuring until a certain depth, and because the slab typically descends at an angle of ~60deg
1006343
You have "windward" and "leeward" - "leeward" slopes face away from the prevailing wind direction.
807687
The main reason is simply that the temperature is too high to maintain them. Glaciers melt in warmer climes. Even the glaciers of Antarctica, the Arctic and the world's greatest mountain peaks are melting in the current warming climate. \n\nThe glaciers of ice-age Britain had no chance when the global temperature rose at the end of that period.
312508
Illinois was almost completely wiped of any high elevating hills or mountains during the Ice Age.  However, there is a small section of the state located in the northwest that was missed by the glacier activity.  These hills are high in elevation for a plains state like Illinois, but aren't tall enough to be classified as mountains.  As far as I know, there isn't even a name for that chain of mounds.\n\nSorry, I know this probably isn't of much help...
883519
There is not really something like a critical point for glaciers. As long as temperatures are rising and are resulting in a negative mass balance the glaciers will keep on melting. But that's not irreversible - thinking rather in "geological" time scales, decades or hundreds or thousands of years. As soon as the mass balance gets positive (due to temperature and/OR more precipitation) glaciers will grow again.\n\nThinking e.g. of a huge volcanic eruption or a comet / asteroid hitting the earth and blowing dust into the atmosphere blocking sun light, that might lead to a global "freezing", maybe even to a next ice age.
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You can rest easy on this one.\n\nNo, an entire glacier will not slip off into the ocean all at once causing a massive global tsunami that wipes out the entire world.\n\nFor one thing, a glacier is a very large collection of ice, which usually has a collection of impurities, such as rocks, plants, frozen mamoths, and such inside it.  These objects inside the glacier have a different structural strength and flexibility than the ice, so the ice tends to crack around them.\n\nEven if the glacier were pure ice, ice only has so much rigidity, and as it grinds it's way toward the sea through the winding valley it inhabits, the glacier will naturally break up into chunks of various sizes.\n\nAs the glacier nears the coast line, these different chunks begin to break off, forming ice burgs of different sizes.  This naturally limits the size of any one ice burg, and that in turn limits the possible tsunami scale waves to rather small splashes.  In fact, to get bigger ice burgs, the part where the ice enters the water must be closer to the same height, so a splash from a very big ice burg would instead be a small ripple as it goes down a much shorter distance in falling into the sea.\n\nYou could go through some complicated equations to figure out just how big a piece of ice could possibly fall into the ocean at any one time, and how far it would fall to figure out just how big a wave it could make, and then determine how far such a wave could propagate before it died out like ripples in a pond, but the basic fact is that no ice burg could cause a massive tidal wave.\n\nPresumably, if the water under the glacier melted really fast, the entire glacier might fall into the ocean, forming many, many small splashes as each piece broke and fell, but again, water is not a perfect lubricant, and this will limit the rate at which they fall, which will prevent a single catastrophic tidal wave, although under certain circumstances, the ice burgs might fall in a pattern that produced very choppy water that ships wouldn't be able to sail in... but again, not on a global scale.\n\nAre government leaders in the US aware of this posibility? NO!  government leaders are barely even aware of how to get themselves re-elected.\n\nIs it too late to do anything about it?  Umm, no.  We could build enormous mirrors in various parts of the world to reflect more sunlight back into space, which should reduce the effects of global warming to some extent.  That, along with using jets to produce global dimming, and changing to less polluting equippment to reduce greenhouse gasses might keep the ice burgs from falling too fast to make choppy water.\n\nIs the USA to blame for what will happen to our planet? of course.  With a population of less than half that of China or india, and much cleaner resources we are obviously the major polluters in the world. \n\nIs this event the next "Mass Extinction?"  only for fish that get in the way of the falling ice bergs.
960781
a precipitous, rocky place; cliff.
167607
Signs of scraping on the rocks as the glaciers went by.\n\nShallow lakes left behind (tarn lakes, kettle lakes and Pater Noster lakes)\n\nGlacial till, or material pushed by the glacier like a bulldozer and then left behind in mounds. These mounds are called moraines.