GLACIERS NOTES!!
Glaciers: 2 Types
 ____________________ GLACIERS: long, slowmoving, streams of ice found in _______________
(high elevation) occupying former river valleys
 ___________________ GLACIERS (ICE SHEETS): very
________ (1000’s of years), thick (1000’s of
meters) mass of ice
________________________________________________
 _____________________: 1.7 Million SQ MI , 3 KM thick
 _____________________: 12.5 Million SQ MI, 5 KM thick
WHERE DO THEY FORM?
• AREAS OF ________________________ OR
______________________________ WHERE THEY
HAVE _______ SUMMERS
• PRESENTLY OCCUPY ________% OF WORLD’S
TOTAL LAND AREA
(COMPARED TO ______% DURING THE
PLEISTOCENE EPOCH)
How long ago was this? _______
HOW DO THEY FORM?
• MORE SNOW MUST FALL THAN ______________
• ZONE OF ______________________ – SNOW TURNS TO ICE AT
UPPER PART OF GLACIER
• ZONE OF ____________________ (_________________) – LOWER PART
• SNOW LINE (_________________________ LINE) LINE WHERE SNOW
IS ________________________________
Process of Glacier Formation
1) SNOWFLAKES ______________
2)SNOWFLAKES ______________
3)FIRST INTO _________ (LIKE PACKED
SNOWBALLS)
4)LOWER LAYERS TURN INTO GLACIAL
_______ (SOLID ICE – NO AIR) UNDER
THE WEIGHT OF OVERLYING FIRN AND
SNOW
Firn
• ________ is an intermediate stage between ______ and
_________________________
• When _________ snow is accumulated than is melted, the snow
clumps together and will ultimately become glacial ice
HOW DO GLACIERS MOVE?
• UNDER THE INFLUENCE OF ___________________
• _________________________ IS THE DRIVING FORCE
• UNDER PRESSURE THE DEEPER ICE BEHAVES LIKE A THICK
________________ (CALLED PLASTIC FLOW) AND __________
DOWNHILL OR _____________ OUT IN ALL DIRECTIONS
(when glacier is about 300 ft. thick)
GLACIER MOVEMENT
• GLACIER ADVANCES
SNOWFALL _____ MELTING
• GLACIER RETREATS
SNOWFALL _______MELTING
• STATIONARY GLACIER
SNOWFALL ______ MELTING
GLACIER FLOW
• SPEED IS LIKE A STREAM – ____________ IN THE MIDDLE / LESS
FRICTION
• fastest movement after 1) __________________, 2) ________________,
and 3) in _______________
• WHY???
______________________ form along ______________ slopes because
upper zone of glacier is ______________ (rarely go deeper than
120ft. )
HOW DO GLACIERS ERODE?
____________________________ erosional agent because of their great
size and weight
Glaciers erode by:
• __________________ – wearing, grinding, scraping rock surface
because rock fragments are frozen into the ice at the bottom
(ROCK FLOUR)
• _________________ – rock fragments loosened, picked up and
carried by glaciers
EROSIONAL FEATURES
• _______________ - Grooves carved into the bedrock by pebbles
and cobbles carried at the bottom of a glacier – can show
direction of glacial movement
• __________________________
• __________________ - TILL - is angular to sub-round and NOT
SORTED AND NOT LAYERED
ERRATIC – EVIDENCE OF GLACIER
EROSION
• A ______________-sized rock dumped by a
glacier. The rock is usually of a
_______________________ that the surrounding
rock…
VALLEY GLACIERS
VALLEY GLACIER EROSIONAL FEATURES
___________________ that were scenic to begin with are
now jagged, angular peaks
GLACIERS MODIFY RIVER VALLEYS BY…
TURNING THE V-SHAPE RIVER VALLEYS INTO
________________ GLACIATED VALLEYS
EROSIONAL LANDSCAPE FEATURES OF
VALLEY GLACIERS
 ________________________: semi-circular shaped bowl created as a glacier
scours back toward the mountain (1st place snow and ice accumulate)
 _____________________: steep-sided, sharp-edged bedrock ridge formed by two
glaciers eroding away on opposite sides of ridges
 ____________________: 3 or more cirques adjacent to one another
 _____________________: glacial lakes produced by glacial scouring- often found
in cirques
 _____________________: valley eroded by a small tributary glacier; floor is at a
higher elevation that valley it feeds into…
VALLEY GLACIER DEPOSITIONAL
FEATURES
_______________________ – unsorted, un-layered pile of till
There are many types of moraines
 ________________ – till along side of glacier
 ___________________ – 2 glaciers come together and the lateral
moraines join in a single ridge
 ____________________ – farthest advance of glacier
 __________________ – glacier retreats, pauses, deposits – will be
parallel to terminal moraine
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CONTINENTAL OR ICE SHEET GLACIERS
• MOST FLOW OVER RELATIVELY FLAT AREAS SO
LANDSCAPE FEATURES ARE LESS DRAMATIC –
ROUNDED HILLS (valley glaciers sharpen and
continental glaciers round)
• LAKES AND SWAMPS
GREAT LAKES
FINGER LAKES
CONTINENTAL GLACIER DEPOSITIONAL
FEATURES

____________________ – glacially formed accumulation of debris

______________________ - ground moraine that is mounded into a stream-lined
oval shape hill (inverted spoon) – steep side points in direction the glacier
came from

_____________________ – large, buried ice blocks melted and left depressions.
Ex. Lake Ronkonkoma

______________________ - deposits made by streams after glaciers melt
(sorted/stratified)
The Milankovitch Cycle
• Changes in the tilt of the Earth’s axis from 21.5º - 24.5º (obliquity – every
41,000 years), changes in the shape of Earth's orbit (eccentricity – every
100,000 years) and axis pointing to Vega instead of Polaris (precession –
+ or - 21,000 years).
• Bottom line – about a 100,000 year cycle
• Since then however, fears of global warming as a result of man-made
greenhouse gas pollution have dominated the environmental agenda –
hard to predict