Climate Change and Glaciers Exam 3 Flashcards
(23 cards)
What are glaciers
A thick mass of ice thatoriginates on land from the accualation, compacion and recrystallization of snow.
- anything form of ice that last all year long
Glacier are dynamic systems
- Mass input as snow
- Snow is transformed into ice
- the ice flows once its thicker than 100ft
- mass leaves the glacier by melting sublimation (ice turns to water vapor) and calving (ice turns ice berg)
Rates of glacial movemnet
- Rates of up to several meters per day (although more commonly 0.1-1 m/yr)
*some glacier exhbit extrtemly rapid movements called surges
Type of glaciers: Alpine (Mantain,Valley)
*Exists in mountains areas
*Ice flows down a valley from high elevation accumaltion zones
Type of glaciers: Continental (Ice sheet)
*Exists on a larger scale than valley glacers (100’s of km squared)
*Two major continental glaciers are presnet over greenlnd and anartica there used to be more.
*Ice flowsout in alldirections from one or more accumaltion zone
Glacial Erosion
*Glaciers are capable of great erosion and sediment transport
*Glaciers erode the land primarily in two ways
Types Glacial Erosion: Abrasion
- Glacial polish rocks within the ice acting like sand paper to smooth and polish the surface below
*Striations - linear scratches inrock aligned with direction of glacial movement
*Chatter marks crescent shape (upstream/ concove)
Types Glacial Erosion: Plucking
Lifting rocks
Types Alpines Glacier land Forms: MORAINES
Lateral
Medial
Terminal
Recessional
Types Alpine Glacier Land Forms:
U-Shaped
Cirques
Artes
Hanging Valleys
Tarns
Horns
Paster noster lakes
Fjords
Moraines
Types of Glacial Deposit: Till
Materials is deposited directly by ice when it melts ( a mixture of all grain sizes including cobbles, sand, silt, and clay.
Moraines
Types of Glacial Deposit: Outwash
Sediment transported by glacial melt water then deposited usually boulders, cobbles and sand.
Erratic - Drumlin - Eskers - Kettels - Braided streams
Types of Glacial Deposit: Glacial Erraties
Rocks deposited by glacial streams (typically braided)
Types of Glacial Deposit: Drumlin
Unlithified material that has been streamline beneath a glacier (gentle slope points in down glacier direction)
Glaciers of the past: Ice house v.s. Hothouse Earth
Time scale of millions of yr
Glaciers of the past: Glacial (Iceages) v.s. Interglacial
Timescale of thousnds of yr
Glaciers of the past:
Currently in interglacial within ice age
the most recent series of ice ages occured during the pleistocene Epoch
The time since the last ice age (Wisconsin) is called the Holocene
Cause of cycle of glacial advance retreat: Eccentricity
Variation in the ellitical shape of the Earth’s orbit
- 100,000 year cycle
Cause of cycle of glacial advance retreat: Obliquity
Variation in tilt of the Earth’s axis ranges from 22.5-24.5 (today it is 23.5)
- 41,000 year cycle
Cause of cycle of glacial advance retreat: Pre of the equinoxes
due to wobble of axis, resulting in equinox occuring at different postions in Earth orbit.
EX: today the morthern hemisphere winter occurs when the Earth is closest to the sun in it elliptical orbit.
- 22,000 year cyle
What if all rhe ice on the earth melted?
- Slightly more than 2% of the worlds water is tied up glaciers on land
- If melted sea level would rise up to 330ft
- west chester high 570Ft - low170ft quadrangle elevation
Climate v.s. Weather
{Weather}
Climate is not the same as weather
- Weather
short term changes (Hours-days)
Difficult to predict
Climate v.s. Weather
{Climate}
Climate
- long Term trend (decades- longer)
Predictable - responds to know global forces
