glacier environments Flashcards
What features/landforms of a landscape indicate that glaciers have been present? (glacial erosion (glacier erodes) and deposition (material that glacier deposits))
EROSION
- chattermarks
- striations
- corries/cirques
- horns
- aretes
- glacier throughs (u shaped valley)
- fjords
DEPOSITION
- moraines
- flutes
- drumlins
- kettles
- esker
- braided stream
moraines
- landforms generated at the margins of glaciers
- larger latero-frontal moraine
- step sided, often ice cored, prone to slope failure
- can also form significant barriers to drainage; impound lakes recieving glacier meltwater
- if barrier is breached/overtopped, glacier lake outburst floods (GLOFs released)
- GLOFS not good
- lose steep rocks that act as natural dams
- not very solid (lose gravel/silt)
- ## bad because many communites live downstream from them
landforms of glacier erosion
- chattermarks
- striations
- corries/cirques
- horns
- aretes
- glacier throughs
- fjords
chattermarks
- small rock bounces off a glacier and creates marks
- small, curved fracture found on glaciated rock surfaces.
striations
a groove or scratch cut into bedrock when clasts embedded in the moving glacier act like the teeth of a giant rasp
corries/cirques
- a bowl shaped depression carved by a glacier on the on the side of a mountain
- semi-circular erosional “hollows”
- created through erosion
- rockies and canadian rockies
- eel glacier on mt anderson
horns
- a pointed mountain peak srrounded by at least three cirques
- remnant peak of mountain
- mountain peack that has been carved out by glacier
- sharp because of erosion
aretes
- a residual knife-edge ridge of rock that seperates two adjacent cirques
- narrow erosional ridge
- sharp because erosion
glacier troughs (u shaped valley)
- a steep walled vallyer shaped by glacial erosion into the form of a U
fjords
- a deep, glacially carved, u-shaped valley flooded by water
glacier depostion
- glaciers carry unsorted debris (variety of shapes, sizes, ex. clay to large boulders)
- deposts debris in a range of settings
- subglacial (environment under glacier)
- supraglacial (environment above glacier ice)
- proglacial (in frost of glacier)
- glaciolacustrine (glacial lake environment)
- glacier are complex
subglacial deposits and landforms
DEPOSITS
- debris in base of ice smeared onto substrae
- forms lodgement till
- hard, compact, no beddding (massive) ( no structure; no big structure)
- often sits on striated bedrock (decreased permeability, no fuild passing, till acts a impermeable barrier)
- an assortment of sediment
LANDFORMS
- lodgement till plain (plain made of lodgement till)
- streamlined forms (parallel to ice flow)
- drumlins
- flutes
- found in front of glacier. made at back of ice. form with ice
supraglacial glacial deposits and landforms
DEPOSITS
- rockfall debris from valley walls
- not very stable
- forms lateral and medial (middle) moranies on glaciers (dark bands)
LANDFORMS
- ice metls slowly from underground supraglacial debris
- forms kettle holes
- changes abledo and how much heat gets into material
- produces irregular, hummocky topography
- ex. dundas valley
- hummocky topography on mars
glaciolacustrine deposits
- lakes common on the margins of glaciers
- fed by meltwater
- sands and gravels depositied on deltas (coarse material; corase material= big grain size)
- clay= decreased permiability= aquitards
- silts and clays carried into lake
- slowly settle out from suspensin
- form laminated fine-grained deposits
- fine material
- icebergs can carry coasre debris into glacier lakes; may contain ice rafted debris (dropstones); the debris melts out from ice
- ice contact glacial lakes : laminated silts and clays
drumlins
- a streamlined, elongated hill formed from glacial till
- hald-egg shaped hills made of till- or may contain sand or berock
- formed at the base of ice- exact mechanism is highly debated
- sound in many placed in southern ontario
- perebrough drumlins
flutes
- narrow, shallow channel that runs nearly vertically down the face of a rock surface
- long, narrow ridges made of till
- till squeezed into linear cavities at base of ice
- small ridges made as glacier is retreating
- ex. saskatchewan glacier
ice marginal landforms
- transverse to ice flow
- push ridges
- glalcier bulldozes
- created by advance of the ice front in winter
kettle holes
- a circular depression in the ground made when a block of ice calves off the toe of a glacier, becomes burried by till, and later melts
- debrs lands on ice and changes insulation and albedo of ice: slows melting
albedo
- refractivity (temp and heat ) of a material
esker
a ridge of sorted sand and gravel that snakes across a ground moraine; the sediment of an esker was depositied in subglacial meltwater
braided stream
A sediment-choked stream consisting of entwined subchannels.
ground moraine
consists of an irregular blanket of till deposited under a glacier. Composed mainly of clay and sand,
iceland
melting of buried ice causses collapse of surface sediments
glaciofluvial deposits
- glacially led rivers/ rivers impacted by glaciers
- proglacial filed will have braided streams with sand and gravel depsotis (have increases permeability)
- aquifers depositited by glaciers
- NW Scotland
- South of vatnajokull ice cap, iceland
