| Term | Definition |
|---|
| esker | narrow ridge of coarse sand and gravel, formed by subglacial meltwater channel. parallel to glacial flow |
| kettle | steep sided hole , formed by gradual melting of large ice block left by glacier, sediment accumulates around block |
| kame | stratified ice deposit; deposited in openings within ice blocks |
| outwash plane | depositional plane of stratified drift |
| cryotic ground | frozen ground |
| active layer | seasonally frozen ground |
| frost heaving | vertical movement of soil/rocks |
| cryoturbation | soil churned by freeze and thaw |
| ice wedge | water enters crack and freezes; crack gets bigger with freeze/thaw |
| pingo | lake drains, talik freezes beneath lake, freeze/thaw pushes frozen block up - creating round dome shape |
| patterned ground | rocks form polygons at surface |
| mechanisms of fluctuations | celestial relations (earth orbit), solar variability, tectonics, atmospheric factors, oceanic circulation |
| glaciers | mass of ice that: forms on land, due to multilayers and snowfall over snowmelt. lowest elevation of formation depends on altitude |
| alpine glacier | glacial formation in mountains, confined by topography (narrow, thin), cirque valley piedmont tidewater |
| continental glacier | create topography, thick large old. ice sheets, ice caps, ice fields, ice shelf |
| icefields | not enough ice to form dome, flow constrained by topography, elongated along mountain chain(peak above ice), ice flows away from summit |
| glacial ice velocity controls | friction (distance from bed & valley sides), steepness (slope), lubrication (free water at the bed) |
| seracs | blocks or columns of ice, formed by intersecting crevasses |
| moulin | forms where a superglacial melt water stream, melts a vertical tunnel through ice |
| tarn | small lake that occupies a rock basin in a cirque or glacial trough |
| what do glaciers move? | loose/fragmented rock (eroded from underlying bedrock or previous glacial deposits), fall-in (rocks fall onto glaciers from surrounding slopes), tributary glaciers (ice from smaller glaciers), fine grained material (carried by meltwater streams) |
| ablation zone | lower part of glacier, net melting/calving/sublimation |
| equilibrium line | separates accumulation and ablation zones |
| firn | granular old snow, forms a surface layer in accumulation zone, intermediate between snow & glacial line |
| accumulation zone | upper part of glacier, net snow accumulation |
| glacier ice formation | formed from snow that does not melt in summer, consolidation and recrystalization of snow into large crystals of ice, snow to firn to glacial ice, lower layers turn to ice under weight of overlying firn & snow, compaction and metamorphism |
| ice shelves | ice sheet attached to land, extends over sea, floats on water |
| ice caps | round with a dome, relatively small |
| ice sheets | most extensive , eg. greenland and antartica |
| cirque glacier | glacier formed in bowl-shaped pit at head of valley, eroded at times of more extensive glaciation |
| lodgemant till | deposited under the ice, dense & rich in clay, compacted by ice |
| ablation till | deposited as glacier retreats, sand/silt, produced through abrasion |
| non cryotic ground | unfrozen ground |
| arete | steep-sided sharp-edged bedrock ridge formed by two glaciers eroding away on opposite sides of a ridge |
| cirque | at head of glacial trough, just below high peaks. shapes depend on : pre glacial topography, duration of glaciation, composition & structure of bedrock, level of activity by alpine glacier |
| factors that influence abrasion rate | amount of debris, sliding velocity, thickness of ice, hardness of bedrock |
| types of glacial erosion | ice push (glacier acts as a bulldozer pushing debris), plucking (removal of blocks from outcrops), abrasion (grinding of bedrock with rock tools) |
| preglacial valley | rivers fit the valley |
| subglacial meltwater | generation 2 ways : 1) melts at surface and flows down to bed. 2) by friction of ice moving over bed. lubricates bed and erodes & transports sediment |
| supraglacial meltwater | water flow on top of a glacier, melts surface & can melt through glacier |
| why do glaciers move? | weight (pressure of mass forces ice to spread out), flow (ice:slippery flows over rock/ soil. lubricated by water at interface between rock/ice as well as between grains), velocity (different speeds between layers stretches ice , causes crevasses) |
| snowline | elevation which snow persists year-round, lower limit of perennial snow (varies with latitude) |
| valley glacier | river of ice confined in valley, transports debris downstream, originate in cirque glaciers |
| tidewater glacier | terminate in body of water, form icebergs |
| moraine | piles of sediment deposited by glacier |
| glacial trough | eroded by passage of valley glacier, steep longitudinal profile, ushaped straight |
| horn | 3 or more cirque adjacent to one another, jagged peak |
| drumlin | low oval hill made of deposited till |
| piedmont glacier | formed by coalescing valley glaciers, no confining valley, spread out , "toothpaste" |
| col | low areas or passages through a ridge that once had glaciers on either side |
| loess | accumulation of wind-blown fine sediment |
| talik | unfrozen patches connects active layer with groundwater |
| hanging valley | tributary valley that no longer meets main valley (often at sites of waterfalls) |
| fjords | glacial troughs filled with ocean water |
| erratic | boulder-sized rock dumped by glacier (usually different composition than surrounding rock) |
| outwash | sorted material from outlet streams as glaciers melt |
| till | unsorted material deposited directly by glacier |
| ground moraine | deposited beneath glacier |
| lateral moraine | pile up along sides of glacier |
| medial moraine | moraine in middle of glacier |
| end (terminal) moraine | marks glaciers furthest advance |
| recessional moraine | standstill during glacier's retreat leaves a series of ridges running across valley behind end moraine |
| types of moraine | ground, lateral, medial, end (terminal), recessional |
Combine with other sets
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