Ch 17 2051

Front 1

ice in glaciers 3

Back 1

paleorecords, 7 million cubic miles, over 10% of land area

Front 2

nunatak

Back 2

Peaks above the snow mass

Front 3

ice shelf

Back 3

Thick, nearly flat sheet of floating ice fed by land glaciers

Front 4

cirque

Back 4

scooped out bowl shaped recess at head of glacier

Front 5

piedmont glacier

Back 5

Broad lobe of ice that terminates on open slopes beyond a mountain front

Front 6

ice is rock

Back 6

metamorphic, it changes

Front 7

Recrystalliaztion

Back 7

Summer air penetrates, evaporates the snow points Empty pore space disappears
Recrystallizes, changing from snow to firn, which is granular
Than keeps compresssing and recrystallizing to become glacial ice

Front 8

snow to ice transformation time depends on

Back 8

temp and precip

Front 9

mass balance of glacier

Back 9

input is accumulation
output in ablation zone, melting (surface, base and internal), deflation and calving, and sublimation

Front 10

Equilibrium Line

Back 10

Boundary between Accumulation and Ablation zones
Where mass loss = mass gain

Front 11

Firn line

Back 11

lowest level to retain fresh snow through the summer

Front 12

two types of movement

Back 12

internal: like a deck of cards also called creep
and basal slip: water as lubricant

Front 13

Glacial Surge

Back 13

Probably results from separation of the glacier from its bed
Hydrostatic pressure (water)
Velocities up to 12 km/year

Front 14

col

Back 14

saddle like depression or pass
from eroding cirques

Front 15

Aretes

Back 15

sawtooth, serrated ridges in glaciated mountains
also from eroding cirques

Front 16

Tarn

Back 16

small (cold) mountain lake

Front 17

Paternoster

Back 17

chain of small (cold) mountain lakes

Front 18

Roche moutonnee

Back 18

asymmetrical hill of exposed bedrock
Abrades the upslope side
Plucks the downslope side

Front 19

Glacial drift

Back 19

general term for all glacial deposits, both sorted and unsorted

Front 20

Unstratified drift

Back 20

material deposited directly by ice
Unsorted
Unstratified

Front 21

Stratified drift

Back 21

material deposited directly by glacial meltwater
Sorted

Front 22

Erratics

Back 22

large rocks, of different origin than the local rocks

Front 23

Till

Back 23

random mixture of rock fragments

Front 24

Glacialmarine drift

Back 24

like till, on seafloor

Front 25

Moraine

Back 25

drift, unrelated to bedrock

Front 26

Ground Moraine

Back 26

widespread, relatively flat, deposited beneath a glacier

Front 27

End Moraine

Back 27

ridgelike accumulation of drift along the end of a glacier

Front 28

Lateral Moraine

Back 28

ridgelike accumulation of drift along the side of a valley glacier

Front 29

Medial Moraine

Back 29

ridgelike accumulation of drift composed of two lateral moraines

Front 30

3 types of stratified drift

Back 30

Outwash: sediment washed out beyond the glacier
Outwash plain: wide field of deposit
(unconstrained by river)
Valley trains : wide field of deposit
(constrained by river)

Front 31

Esker

Back 31

curving, narrow ridge of coarse sand and gravel, a startified drift

Front 32

stratified drifts

Back 32

Esker: curving, narrow ridge of coarse sand and gravel
Drumlin: elongated teaspoon shape
Kame: conical hills deposited by meltwater flowing into funnel shaped holes in the ice

Front 33

4 Unstratified Depositional Features

Back 33

Erratics
Till
Glacialmarine drift
Moraine

Front 34

5 moraines

Back 34

Ground
Lateral
Medial
Terminal
Recessional

Front 35

Stratified Drift 6

Back 35

Outwash plain
Valley trains
Esker
Drumlin
Kame
Kettle

Front 36

Periglacial Landscapes

Back 36

Areas along the margin of glaciers
High elevation
High latitude
Permanent (semi-permanent) ice
Seasonally snow free
Presently > 20% of total land area

Front 37

Permafrost

Back 37

Any permafrost area not covered by glaciers is considered Periglacial

Front 38

2 types of permafrost

Back 38

Continuous Permafrost: Not present under deep lakes and rivers
and discontinuous

Front 39

Active zone of permafrost: thaws daily/seasonally
Talik

Back 39

thaws daily/seasonally
unfrozen ground

Front 40

ground ice

Back 40

frozen in ground, Affects the landscape through Frost Action

Front 41

Frost Action 5

Back 41

Block Field (Felsenmeer):angular rock blocks shattered by freezing
Frost heaving: vertical movement
Frost thrusting: horizontal movement
Cryoturbation: churning of sediments

Ice wedge: ice frozen in ground cracks, expands over time

Front 42

Pingo
Palsa
Patterned ground

Back 42

heaved-up, circular, ice-covered mound
rounded mound of peat, containing thin ice lenses
frost moved accumulations of surface rocks arranged in polygons

Front 43

Solifuction 3

Back 43

A form of mass wasting
Thawed active layer flows down hill
Referred to as gelifluction when ground ice is present

Front 44

Thermokarst Landscapes

Back 44

Results from thermal subsidence and the ice wedge melting
The thawing of ground ice results in uneven, boggy topography

Front 45

Ice age

Back 45

a cold period with at least one glaciation

Front 46

Isotope Record

Back 46

The light isotope (O16) evaporates easier
Rain is enriched in O16
The ocean becomes enriched in O18
The O18/O16 ratio can tell you how much ice there is

Front 47

whats isotopes mean

Back 47

Hence, as glaciers expand, O16 rich precipitation is stored as glacial ice, and the O18/O16 ratio of the remaining sea water increases slightly.

Front 48

More O18 than O16 in water means.

Back 48

More O16 in glaciers and more ice.

Front 49

Paleoenvironmental Reconstruction
4 types

Back 49

Pollen
Lake levels
Ice rafting
and glacial records

Front 50

Younger Dryas

Back 50

11,000 –10,000 BP
A return to the cold
“the Ice-age’s last gasp”

Front 51

Pluvial and interpluvial

Back 51

pluvial: wet, other dry

Front 52

Pluvial due to?

Back 52

Probably due to migration of the polar jet stream, which moves south during cold periods

Front 53

Little Ice Age
Medieval Warm Period

Back 53

1200-1900 AD
800-1200AD

Front 54

Why These Changes?
(little ice age etc

Back 54

Probably due to astronomical effects
Milankovitch Cycles(precession of equinoxes.)
Results in changes in the amount of heat received from the sun

Front 55

Eccentricity

Back 55

how elliptical earth's orbit is, 400k and 100k year cycles

Front 56

tilt

Back 56

of the axis to sun period of 41k years

Front 57

precession

Back 57

change in equinoxes, alters lengths of seasons in relation to how close to the sun and therefore how fast earth is moving in each season.

Front 58

Feedback

Back 58

Changes in solar insolation alone are NOT enough to explain the temperature fluctuations (40 –100 C)

Front 59

Possible positive feedback mechanisms:
3

Back 59

Albedo (snow fields, lack of vegetation)
Dust
Greenhouse gases

Front 60

Long-term variation might be due to 3

Back 60

Continental drift
Ocean spreading
Long term volcanic variability

Front 61

Greenhouse Gases

Back 61

Greenhouse gas concentrations correlate with glacial/interglacial periods

Front 62

glaciation is

Back 62

slow,
deglaciation is rapid