THE BREAKDOWN OF ROCKS AT OR NEAR
THE SURFACE OF THE EARTH
PHYSICAL WEATHERING
THE BREAKDOWN
OF ROCK INTO
SMALLER PIECES
WITHOUT
CHEMICAL CHANGE
ICE WEDGING (FROST ACTION)
WATER HELD IN THE CRACKS
OF ROCKS WEDGES THE ROCK
APART WHEN IT FREEZES
ROOT WEDGING (PLANT ACTION)
TINY ROOTS GROW INTO CRACKS IN
THE ROCK AND THEN AS THE ROOT
GROWS THE ROCK SPLITS
EXFOLIATION
WHEN LARGE MASSES OF ROCK, MAINLY
IGNEOUS, ARE LIFTED UP TO THE SURFACE THE
RELIEF OF OVERLYING PRESSURE CAUSES THE
ROCK TO EXPAND. UPWARD EXPANSION LEADS
TO CURVED BREAKS WHICH MAY PEEL OFF IN
LAYERS
THE BREAKDOWN OF ROCK
THROUGH A CHANGE IN MINERAL
OR CHEMICAL COMPOSITION
OXIDATION
THE CHEMICAL REACTION OF OXYGEN
WITH OTHER SUBSTANCES. IRON IS MOST
EASILY ATTACKED RESULTING IN RUST
(IRON OXIDES)
CARBONIC ACID
WHEN CARBON
DIOXIDE DISSOLVES
INTO WATER. IT
DISSOLVES MANY
COMMON
MINERALS
MINERALS RESISTANCE TO WEATHERING
DIFFERENT MINERALS AND ROCKS
HAVE DIFFERENT PHYSICAL AND
CHEMICAL PROPERTIES WHICH ALLOW
THEM TO WEATHER AT DIFFERENT
RATES
QUARTZ
ALMOST UNCHANGED BY CHEMICAL
WEATHERING. IT IS HARD AND DOES NOT
HAVE CLEAVAGE SO IT ALSO RESISTS
MECHANICAL WEATHERING
FELDSPAR, MICA, CALCITE, AND GYPSUM
AFFECTED BY BOTH TYPES OF WEATHERING AND
WILL BREAK DOWN INTO CLAY WITH CALCITE
AND GYPSUM DISSOLVING AND BEING CARRIED
OFF IN SOLUTION.
SEDIMENTARY ROCKS
SHALE IS THE LEAST RESISTANT TO MECHANICAL
WEATHERING
SANDSTONE IS THE MOST RESISTANT TO
MECHANICAL WEATHERING
THE TYPE OF CEMENT WHICH HOLDS THE
SANDSTONE TOGETHER DETERMINES HOW
RESISTANT THE ROCK IS
CALCITE – LOW RESISTANCE
SILICA - HIGH RESISTANCE
ROCKS WHICH CONTAIN THE MINERAL CALCITE, SUCH AS
LIMESTONE or MARBLE, ARE SOMEWHAT RESISTANT TO
MECHANICAL WEATHERING BUT IS THE LEAST
RESISTANT TO CHEMICAL WEATHERING
EXPOSURE
THE CLOSER TO THE SURFACE OF THE
EARTH, THE FASTER IT WILL WEATHER
- RATE AND TYPE OF WEATHERING DEPENDS ON
EXPOSURE OF ROCKS TO AIR, WATER AND THE AC
OF LIVING THINGS
SURFACE AREA
THE GREATER THE SURFACE AREA
EXPOSED TO WEATHERING THE FASTER
THE RATE OF WEATHERING
**TWO SAMPLES OF THE SAME
MATERIAL HAVING THE SAME MASS
CAN HAVE DIFFERENT SURFACE
AREAS. IF ONE SAMPLE IS A LARGE
PIECE OF MARBLE WITH A MASS OF
50g, AND THE OTHER IS 50g OF MANY
SMALL PIECES OF MARBLE. THE
SMALLER SIZE PIECES WILL HAVE
THE GREATER SURFACE AREA
CHEMICAL WEATHERING IS USUALLY
GREATER IN WARM, MOIST CLIMATES
PHYSICAL WEATHERING IS USUALLY GREATER
IN MOIST AREAS WITH TEMPERATURE
VARIATIONS (COLD AND WARM)
SOIL IS MADE OF LOOSE,
WEATHERED ROCK AND
ORGANIC MATERIAL IN
WHICH PLANTS WITH ROOTS
CAN GROW. THE ROCK
MATERIAL IS COMPOSED OF
SAND, SILT, AND CLAY.
PARENT MATERIAL IS THE MATERIAL FROM WHICH
A SOIL IS FORMED
RESIDUAL SOIL – SOIL THAT HAS THE BEDROCK
BENEATH THE SOIL AS A PARENT MATERIAL
TRANSPORTED SOIL – SOILS FORMED FROM
DEPOSITS LEFT BY WINDS, RIVERS, AND GLACIERS.
A-HORIZON
TOPSOIL
DARKEST COLOR DUE TO ORGANIC MATERIAL
B-HORIZON
SUBSOIL
1) CLAY IS WASHED TO THE SUBSOIL
2) MAY CONTAIN SOLUBLE MINERALS, SUCH AS CALCIUM
AND MAGNESIUM CARBONATES
3) COLOR IS USUALLY RED-BROWN FROM IRON OXIDES THAT
FORM ABOVE AND WASH DOWN
C-HORIZON
MADE OF SLIGHTLY WEATHERED PARENT MATERIAL (ROCK
FRAGMENTS)
UNWEATHERED BEDROCK
TROPICAL SOILS FORM IN AREAS WITH HIGH
TEMPERATURES AND HEAVY RAINFALL. A THICK
INFERTILE SOIL PROFILE ARE RESULTS OF HEAVY
RAIN.
GRASSLAND SOILS FORM IN AREAS WITH ENOUGH
RAINFALL FOR HEAVY GRASS, BUT NOT TREES.
ABOUT 1 METER THICK AND FERTILE
FOREST SOILS FORM IN HUMID REGIONS
WITH COOL SEASONS. SOIL PROFILE IS LESS
THEN 1 METER THICK WITH WELL DEVELOPED
A, B, AND C HORIZONS
DESERT SOILS FORM IN VERY DRY CLIMATES. SOIL
PROFILE IS A FEW CENTIMETERS THICK AND BE
VERY FERTILE WHEN THEY ARE WATERED
ARCTIC SOILS FORM AT HIGH ELEVATIONS AND
HIGH LATITUDES. POORLY DRAINED SURFACES AND
THE BOTTOM LAYERS ARE CONSTANTLY FROZEN.
MASS MOVEMENTS
MOVEMENTS OF LOOSE EARTH MATERIAL
DOWN A SLOPE.
A)
**GRAVITY IS AN AID IN WEATHERING AND
EROSION. STEEP SLOPES WEATHER TO GENTLE
SLOPES.
CREEP - SLOW, IMPERCEPTIBLE DOWN SLOPE
MOVEMENT OF THE SOIL. CAUSES OBJECTS THAT
ARE FIXED IN THE SOIL TO LEAN DOWNHILL.
WATER IN THE SOIL IS WHAT ADDS THE WEIGHT.
MUDFLOW - THE RAPID MOVEMENT OF A WATER
SATURATED MASS OF SOIL.
SLUMP - OCCURS WHEN A SECTION OF LAND
MOVES DOWNHILL AS A WHOLE BECAUSE
OF A PLANE OF WEAKNESS IN THE
UNDERLYING SOIL.
LANDSLIDE - SUDDEN MOVEMENT OF A MASS
OF BEDROCK OR LOOSE ROCK DOWN THE
SLOPE OF A HILL OR MOUNTAIN. (AVALANCHE
- SNOW, ICE, ROCK AND SOIL)
TALUS - IS A PILE OF ROCK FRAGMENTS AT THE
BASE OF A CLIFF.
EROSION
WIND TRANSPORTS MATERIALS BY CAUSING THEIR
PARTICLES TO MOVE IN DIFFERENT WAYS.
SUSPENSION – A METHOD OF TRANSPORT BY
WHICH STRONG WINDS CAUSE SMALL
PARTICLES TO STAY AIRBORNE FOR LONG
DISTANCES.
SALTATION – CAUSES A BOUNCING OF MOTION
OF LARGER PARTICLES. SALTATION ACCOUNTS
FOR MOST SAND TRANSPORT BY WIND.
WIND EROSION IS GREATEST IN ARID CLIMATES
(LOW PRECIPITATION) WITH LITTLE VEGETATION.
(DESERTS AND SEA SHORES)
**ABRASION IS A PROCESS OF EROSION FOUND
IN WIND, WATER, AND ICE. IT OCCURS WHEN
PARTICLES SUCH AS SAND RUB UP AGAINST THE
SURFACE OF ROCKS OR OTHER MATERIALS.
VENTIFACTS ARE ROCKS
SHAPED BY WINDBLOWN
SEDIMENTS.
WIND DEPOSITION OCCURS IN AREAS WHERE WIND
VELOCITY DECREASES.
DUNES ARE PILES OF WINDBLOWN SAND THAT
HAVE A GENTLE SIDE AND A STEEP SIDE.
THE GENTLER SLOPE OCCURS WHEN THE SIDE
ON WHICH THE WIND IS BLOWING (WINDWARD
SIDE). THE STEEPER SLOPE OCCURS ON THE
SIDE PROTECTED FROM THE WIND (LEEWARD
SIDE).
LOESS – THICK DEPOSITS OF FINE LIGHTWEIGHT
PARTICLES (SILT, CLAY) THAT ARE CARRIED BY THE
WIND IN GREAT QUANTITIES OF LONG DISTANCES.
THEY ARE SOME OF THE MOST FERTILE SOILS.
LOUIS AGASSIZ IS KNOWN FOR THE IDEA THAT
GLACIERS ONCE COVERED MANY PARTS OF
THE WORLD.
FORMATION OF A GLACIER
GLACIERS ARE ACCUMULATIONS OF ICE LARGE
ENOUGH TO SURVIVE SUMMER MELT – FORMS FROM
SNOW UNDER PRESSURE WHICH TURNS TO ICE
SNOW LINE – THE LOWEST
LEVEL THAT PERMANENT
SNOWS REACH IN SUMMER
HIGHEST NEAR THE EQUATOR
FIRN IS GRANULAR ICE MATERIAL FORMED IN
SNOW FIELDS FROM FRESHLY FALLEN SNOW
BECOMING COMPRESSED AND RECRYSTALLIZING
THE LOWER LAYERS BECOME ICE AND BEGIN FLOWING
DOWNWARD OR OUTWARD BECAUSE OF OVERLYING
PRESSURE.
Alpine Glaciers (valley glaciers)
Occur in mountain regions above the snow line
Flow downhill and carve out U-shaped valleys
Continental Glaciers (ice sheets)
•
A glacier that spreads over a wide geographic area.
FORM IN POLAR AREAS WHERE THE SNOW
LINE IS CLOSE TO SEA LEVEL AND WIDE
AREAS ARE ABOVE THE SNOW LINE (responsible
for much of the landscape in NY)
20,000 YEARS AGO, NEW
YORK STATE WAS
COVERED BY A HUGE ICE
SHEET THAT ORIGINATED
IN CANADA
Glacier Movement
THE OVERLYING WEIGHT OF SNOW AND ICE CAUSES
GRAINS OF ICE TO PARTIALLY MELT AND REFREEZE. AS
THIS HAPPENS ICE GRAINS SLIP PAST EACH OTHER AND
MOVE DOWNHILL
GLACIERS MOVE MORE RAPIDLY
AT THE SURFACE THAN AT THE
BASE AND FASTER AT THE CENTER
THAN AT THE SIDES. FRICTION
WITH THE VALLEY WALLS SLOW
THE FLOW
* FLOW AT A RATE OF A FEW CM TO SEVERAL METERS PER DAY
CREVASSES ARE CRACKS ACROSS
THE WIDTH OF THE GLACIER
THAT FORM WHEN GLACIERS
MOVE OVER STEEP SLOPES
ICE FRONT IS THE END OF A GLACIER
THE ICE FRONT IS STATIONARY AS
LONG AS THE RATE OF MOVEMENT
AND MELTING ARE EQUAL
A GLACIER RECEDES WHEN IT
MELTS FASTER THAN NORMAL
A GLACIER ADVANCES WHEN THE RATE OF
MOVEMENT IS GREATER THEN THE RATE AT
WHICH IT MELTS.
CALVING IS WHEN BLOCKS OF ICE BREAK
OFF INTO THE SEA
PIECES OF ROCK ARE PICKED UP AS GLACIERS
MOVE AND THEN ARE DRAGGED ALONG THE
BEDROCK AND/OR VALLEY WALL
FINE SAND ACTS AS SANDPAPER
AND POLISH THE BEDROCK
LARGER SEDIMENTS LEAVE
LONG PARALLEL SCRATCHES
CALLED STRIATIONS
** STRIATIONS SHOW THE DIRECTION OF MOVEMENT**
THE FINGER LAKES OF NY WERE FORMED AS
ADVANCING ICE DEEPLY SCOURED OUT VALLEYS
GLACIAL TROUGH ARE FORMED
WHEN A GLACIER CARVE OUT A
VALLEY FORMING A U-SHAPED
VALLEY
VALLEY GLACIERS LEAVE
SHARP MOUNTAIN TOPS
WHILE CONTINENTAL
GLACIERS LEAVE ROUNDED
TOPS
HERE ARE A FEW DEPOSITIONAL
FEATURES OF GLACIERS..
MORAINE IS A GLACIAL DEPOSIT OF UNSORTED
ROCK MATERIAL
GROUND MORAINE – CARRIED ALONG THE
BOTTOM
LATERAL MORAINE – LONG LINES OF ROCK PIECES
ALONG THE VALLEY SIDES
MEDIAL MORAINE – WHEN TWO GLACIERS
COME TOGETHER AND THERE LATERAL
MORAINES JOIN TOGETHER
1.
ARETES
2.
MEDIAL MORAINES
3.
LATERAL MORAINES
4.
CIRQUE
TERMINAL MORAINES – PILES OF UNSORTED SOIL
AND ROCK LEFT AT THE FRONT OF GLACIER
WHERE IT STOPPED MOVING. THIS MARKS THE
FARTHEST ADVANCE OF THE GLACIER.
DRUMLINS – ACCUMULATIONS OF ROCK AND SOIL
THAT BUILD UP IN FRONT IF THE ICE AS THE ICE
MOVED UP AND OVER THESE PILES
ROUND END FACES THE DIRECTION IN WHICH THE
GLACIER ADVANCED
KETTLES – WHEN BURIED ICE LEFT
BY A GLACIER MELTS AND
LEAVES A DEPRESSION
KETTLE LAKE – WHEN
THESE DEPRESSIONS FILL
WITH WATER LIKE A POND