Weathering+and+Erosion

NEAR THE SURFACE OF THE EARTH **
 * I WEATHERING - THE BREAKDOWN OF ROCKS AT OR

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

- 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 - ROOT WEDGING – TINY ROOTS GORW INTO CRACKS IN THE ROCK AND THEN AS THE ROOT GROWS THE ROCK SPLITS

** 1) CHEMICAL WEATHERING- 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

2 ** ) MINERAL MOST RESISTANT TO WEATHERING **

- DIFFERENT MINERALS 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 ARE AFFECTED BY BOTH TYPES OF WEATHERING AND WILL BREAK DOWN INTO CLAY WITH CALCITE AND GYPSUM DISSOLVING AND BEING CARIED OFF IN SOLUTION.

- SHALES ARE THE WEAKEST OF SEDIMENTARY ROCKS

- ROCKS CONTAINING CALCITE ARE MORE RESISTANT TO MECHANICAL BUT CAN BE ATTACKED BY ACIDS IN WATER

- ROCKS CONTAINING QUARTZ ARE RESISTANT TO CHEMICAL AND ARE MOSTLY AFFECTED BY MECHANICAL WEATHERING

** II FACTORS AFFECTING RATE OF 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 ACTION OF LIVING THINGS

SURFACE AREA - THE SMALLER THE SIZE OF THE PARTICLES THE GREATER THE SURFACE AREA EXPOSED TO WEATHERING

CLIMATE - CHEMICAL- WARM, MOIST CLIMATES - PHYSICAL- COLD, TEMPERATURE VARIATIONS

** III SOILS **

SOIL IS MADE OF LOOSE, WEATHERED ROCK AND ORGANIC MATERIAL IN WHICH PLANTS WITH ROOTS CAN GROW. THE ROCK MATERIAL IS COMPOSED OF SAND, DILT, AND CLAY.

1) 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.

** 2) SOIL PROFILE – THE CROSS SECTION OF EARTH EXPOSED BY DIGGING **

- 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

1) MADE OF SLIGHTLY WEATHERED PARENT MATERIAL (ROCK FRAGMENTS)

- UNWEATHERED BEDROCK

** 4) CLIMATE **

- 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 SOILD FORM IN VERY DRY CLIMATES. SOIL PROFILE IS A FEW CENTIMETERS THICK AND BE VARY FERTILE WHEN THEY ARE WATERED

- ARCTIC SOILS FORM AT HIGH ELEVATIONS AND HIGH LATITUDES. POORLY DRAINED SURFACES AND THE BOTTOM LAYERS ARE CONSTANTLY FROZEN.

** 5) MASS MOVEMENT

- MOVEMENTS OF LOOKSE EARTH MATERIAL DOWN A SLOPE

A) ** GRAVITY IS AN AID IN WEATHERING AND EROSION. STEEP SLOPES WEATHER TO GETLE SLOPES

CREEP- SLOW, IMPERCEPTIBLE DOWN SLOPE MOVEMENT OF THE SOIL. CAUSES OBJECTS THAT ARE FIXED IN THE SOUL TO LEAN DOWN HILL. WATER IN THE SOIL IS WHAT ADDS THE WEIGHT

MUDDFLOW- 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- fast movement

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 PLILE OF ROCK FRAGMENTS AT THE BASE OF A CLIFF.

** 6) WIND 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 STEEO 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.

**** 7) GLACIERS **

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.

** 8)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 GLACER 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 NEW YORK)

20,000 YEARS AGO, NEW YORK STATE WAS COVERED BY A HUGE ICE SHEET THAT ORIGINATED IN CANADA.

** 9)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 FROM IS STATIONARY AS LONG AS THE RATE OF MOVEMENT AND MELTING ARE EQUAL

A GLACIER RECEDED WHEN IT MELTS FASTER THAT NORMAL

A GLACIER ADVANCES WHEN THE RATE OF MOVEMENT IS GREATER THEN THE RATE AT WHICH IT MELTS

PEACES 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

STRIATTIONS SHOW THE DIRECTION OF MOVEMENT **

CALVING IS WHEN BLOCKS OF ICE BREAK OFF INTO THE SEA

THE FINGER LAKES OF NY WERE FORMED AS ADVANCING ICE DEEPLY SCOURED OUT VALLEYS

GLCIAL TROUGH ARE FORMED WHEN A GLACIER CARVE OUT A VALLEY FORMING A U-SHAPED VALLEY

VALLEY GLACIERS LEAVE SHARP MOUNTIAIN TOP WHILE CONTINENTAL GLACIERS LEAVE ROUNDED TOPS

HERE ARE A FEW DEPOSTIONAL FEATURES

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 GLASCIERS COME TOGETHER AND THERE LATERAL MORAINES JOIN TOGETHER

CIRQUE - Geology a half-open steep-sided hollow at the head ofa valley or on a mountainside, formed by glacialerosion.
 * VOCABULARY **

ARETE - a sharp mountain ridge.

HORN - a hard permanent outgrowth, often curved and pointed, found in pairs on the heads of cattle, sheep, goats, giraffes, etc.,

COL - A BREAK IN AN ARETE (MOUNTAIN PASS)

TRUNCATED SPUR -

TARN - A SMALL LAKE AT THE BASE OF A CIRQUE

HANGING VALLEY - a valley that is cut across by a deeper valley or a cliff.

CREVASSE - a deep open crack, esp. one in a glacier

ROCHES MOUTONEES - (RESTING SHEEP) AN OUTCROP OF BEDROCK WHICH HAS BECOME ELONGATED.SCULPTED BY A GLACIER ONE SIDE IS SMOOTH AND THE OTHER IS LEFT ROUGH

STRIATIONS -

GLACIER VOCABULARY (DEPOSITIONAL)

DRIFT - be carried slowly by a current of air or water

TILL - an unstratified sediment consisting of particles ofvarious sizes and deposited by melting glaciers or ice sheets.

MORAINE- A) LATERAL - FORMS ALONG THE SIDE OF A GLACIER B) MEDIAL - MERGING LATERAL MORAINES OF TWO GLACIERS FROM A MORAINE IN THE MIDDLE OF THE GLACIER C) GROUND - A MELTING GLACIER DEPOSITS TILL IN A THIN LAYER OVER A BROAD AREA D) RECESSIONAL - DEPOSITS OF TILL THAT FORM AT THE END OF A GLACIER AS IT RETREATS E) TERMINAL - THE END MORAINE FOUND AT THE FARTHEST ADVANCE OF A GLACIER

OUTWASH PLAIN -

KAME - a steep-sided mound of sand and gravel deposited by amelting ice sheet.

KETTLE -

DRUMLIN - a low oval mound or small hill, typically one of a group, consisting of compacted boulder clay moldedby past glacial action.

ROCK FLOUR - finely powdered rock formed by glacial or othererosion.

ERRATICS - not even or regular in pattern or movement

ESKER - a long ridge of gravel and other sediment, typically having a winding course, deposited by meltwater from a retreating glacier or ice sheet. ** 10) EROSION AND DEPOSITION **

EROSION IS THE PROCESS BY THICH EARTH MATERIALS ARE MOVED BY NATURAL AGENTS LIKE WATER,WIND, AND ICE

** RUNNING WATER ** RUNNING WATER - IS THE MOST EFFECTIVE AFENT OF EROSION

THE SUN IS WHERE RUNNING WATER GETS ITS ENERGY

ABRASION IS THE TERM GIVEN TO THE USE OF SAND, PEBBLES AND EVEN BOULDERS AS CUTTING TOOLS TI GRIND AWAY AT THE STREAM BED. DURING THIS PROCESS THE "TOOLS" THEMSELVES WEAR DOWN
 * ROCKS ARE WEATHERED BOTH CHEMICALLY AND PHYSICALLY BY RUNNING WATER**
 * PHYSICAL :**

** RIVERS CARRY ROCK MATERIAL IN THREE WAYS **
 * SOLUTION - THIS IS MATERIAL THAT IS DISSOLVED FROM THE BEDROCK. MOST COMMONLY FOUND IN SOLUTION ARE COMPOUNDS OF CALCIUM AND MAGNESIUM
 * SUSPENSION - WHEN SMALL ROCK PARTICLES SUCH AS CLAY SILT AND FINE SAND, ARE KEPT FROM SINKING BY THE TURBULENCE OF THE STREAM. THIS GIVES THE WATER A MUDDY LOOK.
 * BED LOAD- SAND, PEBBLES, AND SOME BOULDERS WHICH MOVE ALONG THE STREAM BED.


 * CARRYING POWER

CARRYING POWER: IS INDICATED BY BOTH THE TOTAL AMOUNT OF SEDIMENT IN A STREAM AND BY THE SIZE OF THE PARTICLES BEING MOVE **
 * THE STREAM DISCHARGE AND SPEED WILL DETERMINE THE CARRYING POWER OF THE STREAM
 * DISCHARGE IS THE VOLUME OF WATER FLOWING PAST A GIVEN POINT AT A GIVEN TIME.
 * SPEED IS GENERALLY DETERMINED BY THE STEEPNESS, OR GRADIENT OF ITS BED
 * A STREEM MOVING AT HIGH SPEED WITH A HIGH DISCHARGE CAN CARRY MUCH LARGER SEDIMENTS THEN A SLOW MOVING STREAM. EXAMPLE: SPRING TIME SNOW MELTING AND EXCESSIVE RAIN

THE RIVER VALLEY
 * RIVERS TENT TO HAVE A V SHAPED VALLEY BECAUSE THEY TEND TO FLOW AT HIGH SPEEDS AND DIG INTO THE STREAM BED.

BASE LEVEL IS THE LOWEST LEVEL A RIVER CAN CUT INTO ITS BED. TO FORM A PERMANENT STREAM RAIN WATER MUST FLOW DOWN A SLOPE AND DIG DEEP ENOUGH TO CUT INTO THE WATER TABLE. THIS WEARING AWAY OF THE LAND TO FORM A STREAM VALLEY IS CALLED HEADWARD EROSION.

A ** DIVIDE ** IS AN AREA OF HIGH LAND THAT SEPARATES ONE RIVER VALLEY FROM ANOTHER. ON EATHER SIDE OF A DIVIDE A RIVER SYSTEM MAY FORM. WATERSHED IS ALL OF THE LAND THAT DRAINS INTO THE RIVER EITHER DIRECTLY OR THROUGH ITS TRIBUTES

WATER FLOWING OVER A STEEP CLIFF WILL RESULT IN A WATERFALL. WATERFALLS ARE NOT PERMANENT STRUCTURES UNDERMINEG IS THE EROSIONAL PROCESS OCCURRING AT THE BASE OF A WATERFALL. HERE WATERCARRYING SEDIMENT PLUNGES DOWN AND BACK INTO THE STREAM VED AND CLIFF BELOW. THIS CAUSES THE ROCKS AT THE TOP OF THE FALLLS TO OVERHANG. OVER TIME THIS OVERHANG WILL COLLAPSE AND THE STREAM WILL MOVE BACK TOWARDS ITS SOURCE
 * WATERFALLS

** RIVER DEPOSITION

EROSION AND DEPOSITION IN A RIVER RUNNING WATER DEPOSITS WELL-SORTED PARTICLES
 * DEPOSITION OCCURS WHEN A STREAM EITHER DECREASES IN SPEED OR DISCHARGE.
 * GENERALLY THE SPEED DECREASES WHEN ITS SLOPE DECREASES OR IT BED WIDENS. THE GREATEST LOSS OF SPEED OCCURS WHEN A RIVER EMPTIES INTO A QUIET BODY OF WATER
 * A DECREASE IN DISCHARGE WOULD OCCUR IF A RIVER TRAVELED THROUGH AN AREA WITH LOW POPULATION.
 * AS RIVERS BEGIN TO DECREASE THEIR SLOPE THEY MOVE SLOWER AND WLL BEGIN TO MOVE SIDE TO SIDE
 * AS THE VALLEY WALL ON EITHER SIDE IS ERODED THE VALEY FLOOR IS WIDENED
 * A FLOOD PLAIN THE THE WIDENED VALLEY FLOOR AREA WHICH WUKK ACCUMULATE WASTER DURING TIMES OF EXCESS RAIN WHEN THE RIVER FLOODS.
 * MEANDERS ARE BROAD CURVES IN THE RIVER (EACH BEND OR TURN)
 * EROSION IS GREATEST ON THE OUTSIDE OF A MEANDER WHERE WATER IS FLOWING THE FASTEST (CUT BANK)
 * DEPOSITION IS GREATER ON THE INSIDE OF THE MEANDER WHERE THE WATER FLOWS SLOWER. (FILL BANK)
 * OXBOW LAKE- MEANDERS CAN ONLY BECOME SO LARGE BEFORE THEY BREAK THROUGH INTO ANOTHER MEANDER. THE RIVER THEN DEPOSITS MUD AND SILT ALONG THE END OF THE ABANDONED MEANDER. THE NOW SEPARATED MEANDER BECOME A LAKE

VERTICAL SORTING - WHEN SEDIMENTS ARE SUDDENLY DEPOSITED INTO WATER. THE PARTICLES SEPARATE BY SIZE WITH THE LARGEST ON THE BOTTOM AND SMALLEST OF TOP.

HORIZONTAL SORTING- THEN RIVERS EMPTY THEIR SEDIMENTS INTO QUIET BODIES OF WATER. PARTICLES ARE SORTED BY SIZE WITH LARGER PARTICLES BEING FOUND CLOSER TO THE SHORE AND SMALLER PARTICLES BEING CARRIED OUT INTO THE BODY OF WATER TO BE DEPOSITED.

DELTA- A FAN SHAPED DEPOSIT OF SEDIMENT AT THE MOUTH OF A RIVER ALLUVIUM- DEPOSITS MADE BY STREAMS ON FLOOD PLAINS OR ALLUVIAL FANS. SEDIMENTS ARE SORTED BY SIZE ALLUVIAL FANS- A FAN SHAPED DEPOSIT FOUND AT THE BASE OF A STEEP MOUNTAIN WHERE A STREAM SUDDENLY SLOWS DOWN ALLUVIAL CONE- A STEEPER ALLUVIAL FAN ; FORMS IN DESERT OR SEMI-ARID (DESERT) CLIMATE OXBOW LAKE- NATURAL LEVEE- YAZOO STREAM- A TRIBUTARY THAT FLOWS PARRALEL TO THE MAIN STREAM FOR A CONSIDERABLE DISTANCE BEFORE JOINING IT
 * VOCABYLARY !**