Please use the following information to answer questions I will ask you next:

Slide #1-Alpine Glaciers
Valley Glaciers are tongues of ice that travel down valleys in the mountains. The valleys were originally formed by stream action. Some of these glaciers range in length from 325 feet to 60 miles. 

Piedmont glaciers are glaciers that reach a flat area and escape the confines of the valley walls. Sometimes several valley glaciers coalesce at the base of a mountain range to form the piedmont glacier. 

Cirque Glaciers are very small glaciers confined to the basins where they originated. There is an amphitheater-shaped depression that is often times referred to as bowls.Cirque glaciers often deposit a ridge of till at the down-ice edge of a cirque and this accentuates the bowl-shaped appearance. When the ice disappears due to climate change, the erosional cirque is left behind often forming a natural basin where water accumulates. Cirque lakes are often called tarns. 

Several cirque glaciers may jointly feed a valley glacier. Many cirque glaciers today represent the remnants of previously larger alpine glaciers. Many of them are located towards the north or northeast shading them from the sun. 

At the farthest upslope edge of an alpine glacier lies the glacier’s head. The head of the glacier abuts the steep bedrock cliff that comprises the cirque headwall. The downslope part of the glacier is called the terminus or glacier toe. 

Slide #2-Formation of Glacial Ice
Snow is not merely frozen water. Snow floats to earth as lacy hexagonal crystals that are only 10% as dense as liquid water. 

Some melting of the outer “points” of the crystals may take place and change them into irregular but more spherical grains.This process can be aided by the melting and refreezing of snow. Ice can melt at a lower temperature if it is under enough pressure. 

Neve-The pore spaces with trapped air start getting squeezed out by the overlying weight. It is somewhat similar to the crunchy substance that forms within the top of the snow after it melts a bit during the day and then refreezes at night. Mountaineers like Neve because the sharp points of their axes and poles hold firmly into it. 

Slide #3-Glacial Ice
Glacial ice takes on bluish tinge because the whitish crystals in ice are air.The ice crystals have increased in size by this point and very little air remains.The glacial ice reflects increasing amounts of shorter wavelengths of light, which is the blue part of the spectrum.

We usually think of ice as being a brittle substance that breaks rather than bends and resists any sort of deformation. Cracks and crevasses often appear on the surface of a glacier. 

Tidewater glaciers (pictured in the image) end at the sea, calving (breaking off) to form floating ice called icebergs.Ice is less dense than water and that is why icebergs float. 

Icebergs form when glaciers meet the ocean. Such an iceberg was involved in the tragic sinking of the Titanic in 1912. In 2000, an iceberg the size of Rhode Island broke away from Antarctica and in 2002 an iceberg the size of Connecticut broke away from Antarctica.   

The ends of these tidewater glaciers are dangerous areas because large waves can be created as huge blocks of ice topple into the water. Even near an area that is calving you can hear what sounds alternatively like thunder, gunshots, loud groans, and gusts of wind. The booming and crashing noises echo in the valley. 

Slide #4-Movement of Glaciers
The average glacier moves between 4 inches to a foot a year. The movement of 333 feet a day has been recorded.  Also, the flow is often erratic, with irregular pulsations and surges over a short span of time. The rate of flow usually increases in summer and slows in winter. A lot has to do with the variations in ice accumulations and the steepness of the underlying surface. 

Basal Slip-Partial melting of the bottom of the glaciers is due to earth’s heat and friction at the bottom of the glacier. The glacier slides like a wet bar of soap slides on the floor of your shower. 

Basal slip happens most often during the warmer months and rarely during cold months. Also it occurs more on steep slopes than flat areas. Meltwater sinks to the bottom of the glacier and becomes a slippery layer on which the glacier can slide. Some surge events result from the buildup of water pressure under the glacier, sometimes enough to actually float the glacier slightly, detaching it from it from the ground during the surge. As the surge begins, ice quakes are detectable and ice faults are visible. 

Another cause of glacier surge is the presence of a water-saturated layer of sediment, the so-called soft bed beneath the glacier. This is a deformable layer that cannot resist the tremendous sheer stress produced by the moving ice of the glacier. 

Where a glacier locally flows over a steep descent, such as a subglacial cliff, an icefall develops in the brittle upper ice. The ice breaks into a morass of unstable ice blocks that ride on the rapidly flowing ice below. It is equivalent to a waterfalls on a river. This is the most rapidly moving part of the glacier. It is also the most treacherous part of the glacier to cross because the ice blocks can shift at any time. 

Plastic Flow of Ice- There is an oozing outward from around the edge of an ice sheet or from the toe of an alpine glacier. Different parallel layers (ice, neve, and snow) glide over each other like spreading a deck of cards. Less erosion takes place than basal slip. 

The fastest-moving ice is that at and near the surface, with speed generally decreasing with depth. If a glacier is for instance confined to a valley, the center moves faster than the sides.   

Slide #5-Glacial Erosion
Mountains are sharpened and valleys are deepened and made more linear. The entire landscape becomes more angular and rugged. 

The rate of glacial erosion is determined by 4 factors. #1: Rate of glacial movement, #2: thickness of the ice, #3: shape, abundance, and hardness of the rock fragments contained in the ice at the base of the glacier, #4: the erodibility of the surface beneath the glacier.  

Glacial Plucking-The partially melted lower portion of the glacier can refreeze around rocky protrusions. This pries the rock loose. As the ice moves along, these particles are plucked out and dragged along.Glacial plucking is especially effective in bedrock that has a lot of cracks. Plucking tends to roughen the underlying surface. 

Glacial Abrasion-Despite its appearance, ice is actually not that hard a substance. Glacial abrasion occurs when bedrock is worn down by rock debris (which was picked up by glacial plucking) being dragged along in the moving ice. Smaller rocks act like sandpaper. Larger rocks in the glacier act much like a chisel, gouging the underlying surface and producing glacial striations. Abrasion produces polished surfaces, striations (fine parallel indentations), and grooves (indentations deeper and larger than striations). Some rocks shine after the glacier has retreated and it is called glacial polish.  

High rates of glacial abrasion generally require fast moving ice. The greater the weight of the overlying ice, the more rapidly the glacier will move. As a result, erosion by a glacier flowing through a mountain valley may be more rapid towards the middle than its edges.  

Crevasses- result from friction with valley walls when the central part of the glacier moves forward quicker than the sides. It also results from stretching as the glacier passes over downstream side of the slopes or compression as the glacier passes over up-valley slopes. Traversing a glacier is dangerous because a thin veneer of snow sometimes mask the presence of a crevasse. Crevasses can be 165 feet deep, but won’t get any deeper because the ice is not brittle enough to crack below that point. Crevasses slowly open and close as the glacier moves. 

RochesMountonnees- bedrock hills that are smoothly rounded and gently sloping on the up-ice side by abrasion with plucking evident on the abrupt down-ice side. The downside is steeper and more irregular than the up-ice side because of the plucking. 

Slide #6-Transportation by Glaciers
These melt streams continue their flow as a subglacial stream either within the ice or along the interface between the glacier and bedrock. This also increases the lubricating affect of the glacier which can accelerate the flow of ice. Meltwater streams have the grayish appearance of skim milk. 

Sediments deposited by glacial meltwater that are sorted by size are termed sorted drift. Sorted drift consists primarily of sand and gravel because meltwater is not capable of moving much larger particles. Most of the meltwater deposition involves debris that was originally deposited by iceand subsequently picked up and deposited by meltwater beyond the outer margin of the ice. 

Meltwater streams laden with sediment commonly come from the glacier’s terminus. The sediment is called glacial outwash with larger gravel first, followed downstream by progressively smaller particles. These areas are mined for road gravel and other construction projects. This finely ground rock material is known as glacial flour.

Subglacial Meltwater Erosion- Streams flowing below the glacier not only transport rock, they can erode smooth grooves and channels into bedrock. 

Slide #7-Glacial Till
Most glacial till fragments are angular because they have been held in position while carried in the ice. Larger till sediments were carried within the glacier or on the top of the glacier because rocks underneath the glacier get crushed. Such till is poorly sorted and is difficult to cultivate for farming. 

Basal Till- is plastered on the ground at the base of the glacier in a way that is somewhat similar to peanut butter being smeared onto bread with a knife. Because of the intense pressure at the base of the glacier (due to the weight of the ice) basal till is usually quite dense and relatively fine grained because it has been ground and crushed.

Ablation Till- is sediment that is carried within or on top of the ice and deposited when glaciers melt. Ablation till usually contains coarser fragments such as boulders because they are not crushed at the base of the glacier. Ablation till tends to be even less sorted than basal till. 

Sometimes large boulders that can be house size are carried by the glacier. They may be very different from the local bedrock and called glacial erratics. They give a clear indication that ice once covered the land. 

Slide #8-Cirques
A cirque has a very steep (often perpendicular) head and side walls. The floor is either gently sloping or flat. Sometimes the cirque floor is even gouged out enough to form a basin. It is the first landform feature produced by alpine glaciation, essentially rock being quarried out of the mountainside. Cirques vary considerable in size ranging from a few acres to a few square miles in extent. 

Slide #9-Glacial Diagram
Arete-Where cirques are close together, the ridge between neighboring cirques is reduced to little more than a steep rock wall. Where several cirques have cut into the ridge from opposite sides of a divide, a narrow, jagged, serrated spine of rock may be all that is left of the ridge crest called an arête. 

Horns- is a steep-sided, pyramid-shaped mountain peak formed by expansive quarrying where three or more cirques intersect. Two or three cirques may develop near the top of a mountain and growing by erosion they intersect. There is nothing left of original rounded mountain besides a steep sided, sharp edged peak.

The Matterhorn Mountain in Switzerland is the world’s most well-known horn. The Matterhorn Mountain inspired the Matterhorn Bobsled ride at Disneyland.  

Glacial Trough-Some alpine glaciers do little more than erode cirques, presumably because of the insufficient accumulation of ice to force downhill movement. Most alpine glaciers flow from highland icefields to preexisting valleys and reshape them. The cross-sectional profile of a glacial valley is an ice eroded ‘U’ shaped valley. The physical weathering from the freeze-thaw cycle has loosened rock along the cliffs and made them steep. A glacier fills the entire valley and actively erodes spurs that have protruded into valley.

The general course of the glacial valley is straight because glaciers do not meander like streams. A glacier can also grind away spurs separating side canyons. Unlike water, ice can flow uphill if blocked by resistant rock on the valley floor. This permits rock fragments to be dragged out of depressions in the valley floor. 

Hanging Valleys- When a river is joined by a tributary, the water surface of both streams is at the same level, and the floors of the valleys tend to be concordant as well. 

Valley glaciers also maybe fed by smaller tributary glaciers. The smaller tributary valleys cannot widen and deepen as much as main valley glaciers. When occupied by glaciers and thus covered by a relatively level field of ice, main and tributary valleys may appear equally deep. When the ice melts, the valleys are of different depths because the smaller tributary glaciers could not erode as deeply as the large main valley glacier. Yosemite has several examples of this. 

Slide #10-Glacial Steps
A glacier grinding along the valley floor does not produce a smooth surface. Resistant rock on the valley floor is gouged less deeply than weaker or more fractured rock. Such landforms are known as glacial steps. 

While the ice is still present, crevasses or even icefalls develop in its surface where it flows over the steps. Many mountaineers have been crushed by falling ice while traveling through icefalls. 

A postglacial stream that flows out of a cirque and down a glacial valley includes rapids and waterfalls. They are named paternoster lakes because they resemble the rosary beads. Paternoster lakes may have formed from the differing resistance of rock to glacial processes or from damming by glacial deposits. 

Slide #11-Lateral vs. Medial Moraines
The principle depositional landforms associated with mountain glaciations are moraines. It is important to note that a well-developed moraine forms only when the ice is there for a long period of time. Only then can persistent internal motions of ice continually bring forth enough sediment for a visible ridge to grow. 

A large glacier may produce a moraine that is so high that a person in good physical shape may require more than an hour to reach the top. Moraines are also dangerous to hike over if their sides are steep and till is loose. Large boulders are mixed randomly with rocks, sand, and clay. A careless hiker may dislodge the boulders and send them tumbling to the base.  

Medial Moraine- They often continue down the middle of the combined glacier as a dark band of rocky debris known as a medial moraine. Medial moraines cause the characteristic dark stripes seen on the surface of many alpine glaciers. 

Slide #12-Terminal Moraines 
Terminal Moraines are where eroded debris reached the glacier’s farthest extent. At the toe of glacier, sediment is carried forward by the “conveyor belt” of ice and is deposited in a jumbled heap of material of all grain sizes, forming a curved depositional ridge. Think of an old-fashioned airport conveyor belt that carries the suitcases to the end of the belt and then dumps them into a pile. Lakes may form behind terminal moraines after a glacier’s retreat, with the moraine acting as a dam.

The debris is partly material deposited by the glacier and partly rock that falls or is washed down the valley walls.