chapter 6 terms & in-class
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112 terms
Terms | Definitions |
|---|---|
 glacier | a river of ice |
| valley glaciers | glaciers that exist in lofty mountain areas, where they usually follow valleys. (advance very slowly) |
| ice sheets | enormous masses that flow out in all directions from one or more centers and completely obscure all but the highest areas of underlying terrain (appear like an upside bowl and are at least 1 million Sq miles) |
| ice caps | glacial ice that covers some uplands and plateaus (like ice sheets but smaller less than 1 million Sq miles) |
| piedmont glaciers | valley glaciers that reach the valley floor and spread out |
| crevasses | large cracks in the surface of a glacier caused by uneven movement are known as _______________ (can reach a depth of 165 feet) |
| zone of accumulation | zone in which snow accumulation and ice formation occur |
| zone of wastage | zone where there is a net. loss to the glacier when the snow from the previous winter melts as does some ice |
| ablation hallows | irregular feature created in the surface of a glacier due to differences in wind and temperature on the surface of a glacier are called __________ |
| glacial budget | the balance or lack of balance between accumulation at the upper-end of a glacier and loss at the lower end |
| plucking | process by which a glacier flows over a fractured bedrock surface it loosens and lifts blocks of rock and incorporates them into the ice (occurs when melt water penetrates cracks and joints) |
| abrasion | process by ice and its load of rock fragments sliding over bedrock, and they function like sand paper to polish the surface (friction) |
| rock flour | pulverized rock produced by the glacial gristmill |
| trough | another name for a glacial valley |
| hanging valleys | valleys created by a tributary glacier, that enters the main valley a great distance above the floor are known as ____________ |
| cirque (cwm) | a bowl shaped basin at the head of a glaciated valley produced by frost wedging |
| aretes | form where two cirques are located back to back and create a sharp-edged ridge |
| horns | pyramid shaped peaks created by the presence of 3 (+) cirques is known as a ______________________ |
| fjords | flooded glacial valleys caused by an increase in sea level |
| drift | any material carried and deposited by a glacier is known as ______________ (early scientists thought flooding was the reason for the moving of the material) |
| till | any material carried by a glacier and dropped on land by a glacier |
| stratified drift | any material carried by a glacier and then dropped in water |
| erratic | any boulder moved by a glacier is known as a(n) ____________ |
| lateral moraines | ridges of till that are left along the sides as a glacier flows |
| medial moraine | a ridge of till formed where two glaciers form together |
| end moraine | a ridge/mound of till that forms at the terminus (end) of a glacier |
| ground moraine | all the till that is left behind from a glacier |
| outwash plain | the flat area at the end of a glacier where meltwater flows and deposits sediments (have a braided stream pattern) |
| valley train | a relatively narrow body of stratified drift deposited on a valley floor by meltwater that are from a valley glacier |
| kettles | basins or depressions within the end moraines, outwash plains |
| esker | a winding ridge, that once was a river that flowed underneath a glacier is a(n) ____________ |
| pleistocene epoch | division of the geological time scale (2 mill - 3 mill years ago) |
| pluvial lake | a lake formed during a period of increased rainfall |
| ephemeral streams | streams that only carry water in response to rainfall |
| interior drainage | having a discontinuous pattern of intermittent streams that do not flow out of the desert to the ocean |
| alluvial fan | formation when run off falls from the base of mountain |
| playa lake | a temporary lake that will last only a couple of days |
| deflation | the lifting and removal of loose material with downward movement |
| blowouts | shallow depressions (1m-45m in depth) |
| desert pavement | layer of coarse material (rock and pebbles) on a desert floor formed by deflation |
| loess | deposits of wind blown silt |
| dunes | mounds/ridges of sand blown from the wind |
| slipface | the leeward side of a sand dune |
| cross-beds | layers inclined in the direction the wind is blowing |
| barchan dunes | dunes: solitary, tips point down wind, limited amount of sand, form on flat land, no vegetation, migrate slowly, max. 30 meters tall |
| transverse dunes | dunes: steady winds, lots of sand, no vegetation, series of troughs, ridges perpendicular, up to 200 meters tall |
| barchanoid dunes | dunes: cross between barchan and traverse dunes, moderate amount of sand, similar to traverse dunes but with tips, tips point down wind |
| longitudinal dunes | dunes: long ridges of sand that form parallel to the prevailing wind and where sand supplies are moderate |
| parabolic dunes | dunes: vegetation partially covers land, on coastlines, tips point into wind, strong winds, abundant sand |
| star dunes | dunes: isolated hills of sand, variable wind direction, up to 90 meters tall |
| Louis Agassiz | the father of glaciology |
| 7 | # of john hancock (if stacked on top of each other) would equal the amount of ft the glaciers covered 15,000 years ago over boston |
| 4 | # of ice ages North America has undergone in the past 450,000 years |
| cordilleran | during the last ice age the three ice sheets that covered north america were ____________________, Laurentide , and Greenland |
| laurentide | during the last ice age the three ice sheets that covered north america were Cordilleran ,___________________, and Greenland |
| greenland | during the last ice age the three ice sheets that covered north america were the Cordilleran , Laurentide , and __________________ |
| snowline | elevation above which snow remains year-round is the |
| equator | where is the snowline highest |
| firn (neve) | snow that has survived one summer and has begun the process of transformation into ice (usually 25 years) is called |
| river of ice | a glacier is a_________________ |
| ice shelf | when a continental glacier reaches an ocean and spreads out |
| tidewater glaciers | valley glaciers that end in a lake or ocean |
| their own weight | what is the cause for glaciers flowing ? |
| plastic | the fluid like movement of a glacier can be described as ___________ |
| retreating (recession) | a glacier that is melting faster than it is moving forward is ___________ |
| bergschrund | a crevasse that seperates flowing ice from the head of a glacier is a _______________ |
| serac | (from the french) _____________ is a tower of unstable ice that forms between crevasses, commonly in ice falls or other regions of accelerated glacier flow |
| striations | _______________ indicate the direction that the glacier is moving |
| grooves | deep striations are known as ___________________ |
| truncated spur | the tip of the end of an arete. it is cut by another glacier |
| triangular facet | the triangular face where an arete is cut off by another glacier |
| col | an arete that takes on a saddle shape |
| nunatak | a mountain peak that sticks out above a glacier is called a _____________ |
| moraine | any material that is pushed by a glacier is known as a ___________________ |
| terminal | (end moraine) at the absolute farthest point a glacier has reached |
| recessional | (end moraines) that mark the one-time location of the end of a glacier |
| ogives | bands of light and dark snow on a glacier are known as ____________ |
| light | what is the color of the bands of ogives during winter months ? |
| dark | what is the color of the bands of ogives during summer months ? |
| cryconite | a depression in the surface of a glacier created by the heating of rocks is called a ___________________ |
| glacier tables | ______________ are created when a boulder is protecting the ice below it from ablation during sunny weather |
| penitents | spires of ice found in the tropics due to differences in sublimation are known as ____________ |
| sun cup | an ablation hallow that develops during intense sunshine |
| moulin | a nearly vertical channel in the ice that is formed by flowing meltwater |
| glacial milk | what is the mixture of rock flour and water called ? |
| roche mountonee | ramp shaped mountain made by rock that is carved by a glacier, steeper side represents the direction the glacier was moving (literally means "sheep back") |
| drumlin | a ramp shaped DEPOSIT of sediment with one shallow side and one steep-side is known as a _______________ (shallow side represents direction the glacier is moving) glacier moves up the steep end of the deposit. |
| crag and tail | a glacially eroded rocky hill with a tail of TILL formed down-glacier of it is known as a _________________ |
| kame | a cone shaped deposit of sediment (formed by a river flowing over the surface of a glacier and into a crevasse |
| kame delta | a deposit of sediment formed where a glacial stream entered into a proglacial lake |
| varves | bands of light and dark sediments (different from ogives, they are horizontal) |
| winter | what time of year is represented by dark varves |
| summer | what time of year is represented by light varves |
| jokulhlaup | a giant glacial flood often caused by volcanism |
| glacial lake missoula | giant lake that was built by a glacier acting as a damn, channeled scab lands by a glacial lake outburst |
| dropstone | a rock that was carried by a glacier or iceberg, deposited as the ice melted, and became part of the bedrock |
| pater noster | latin word for "our father" |
| our father prayer | what were the Pater Noster lakes named after, (they appear as if connected like rosary beads) |
| moraine dammed lake | when an end moraine dams the melt water from the glacier behind it |
| kettle pond | kettle that fills with water (ex. Walden Pond) |
| cirque lake (tarn) | when a cirque fills with water (created in mountains) |
| calving | when a glacier reaches the ocean or any large body of water, large pieces of the glacier break off. this is known as ____________ |
| (arroyo) (wadi) (donga) (nullah) | names for ephemeral streams - streams that carry water only in response to rainfall |
| de geer | moraine with ridges underwater |
| chatter marks | multiple half moon shaped fractures on glaciated rock surfaces |
| crescentic gouge | 1 individual half moon shaped fracture on glaciated rock |
| inselberg | an isolated rocky hill or mountain rising above a peneplain in a hot, dry region |
| ablation | the loss at the lower end of a glacier |
| glacier | is a thick mass of ice originating on land from the compaction and recrystallization of snow |
| eccentricity | Variations in the shape of Earth's orbit about the Sun is known as |
| changes in earths orbit | The cause of the most recent variable climate change and series of glacial episodes ("Ice Ages") is most probably related to |
| Interglacial stages | represents periods of time between glaciation events during the Ice Age. |
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