SEDIMENTARY ROCKS-MINERAL OR ROCK FRAGMENTS OR MATERIAL OF
ORGANIC ORIGIN ARE ERODED OR DISSOLVED AND THEN DEPOSITED IN
LAYERS AT EARTH'S SURFACE
CRUCIAL FACTORS:
SOURCE ROCK FROM WHICH
SEDIMENT DERIVED
TRANSPORT MECHANISM
(WIND, WATER, ICE)
SITE OF DEPOSITION (RIVER,
LAKE, OCEAN, DESERT)
PLATE TECTONIC SETTING
SEDIMENTS 5% OF EARTH'S
CRUST, BUT MOST COMMON
SURFACE ROCKS, RECORD
EARTH HISTORY, & VALUABLE
FOR RESOURCES (oil, gas,
coal, building material)
SEDIMENTARY ROCK TYPES
CLASTIC SEDIMENTS: GRAINS
PRODUCED BY MECHANICAL OR
CHEMICAL WEATHERING AT
EARTH'S SURFACE
(EXAMPLE: SANDSTONE)
BIOCHEMICAL SEDIMENTS:
MATERIAL OF ORGANIC (LIVING
THINGS) ORIGIN SUCH AS
SHELL OR CORAL FRAGMENTS
(EXAMPLES: LIMESTONE, COAL)
CHEMICAL SEDIMENTS:
INORGANIC CHEMICALS
PRECIPITATED (CRYSTALIZED)
FROM WATER
(EXAMPLE: SALT DEPOSITS)
Size and shape of
sedimentary
grains reflects
transportation
history.
Beach
sand
Davidson 4.20
Large grains indicate
transport and deposit by
strong currents:
mountain streams,
beaches with large
waves, or glacial melt
streams
SEDIMENTARY
ROCK TYPES
Deposited by moderate
currents that removed
finer sediment: rivers,
coasts with moderate
waves, wind-produced
dunes.
Deposited by gentle
currents, so small
particles settle out of
the water: deep
ocean, coasts with
weak tides
Davidson 4.19
COMPACTION, LITHIFICATION, DIAGENESIS
UNCONSOLIDATED SEDIMENT TURNS INTO HARD
SEDIMENTARY ROCKS
Similar to snow turning to ice
Davidson 4.25
Sedimentary Structures:
Cross-bedding: sediment
carried by moving fluid
(water, air)
Ripple Marks
Graded Bedding: grains
become finer upward in
layer
Mud Cracks: shallow water
deposit
Davidson 4.24
MIDWEST HAS FEATURES
FORMED BY SEDIMENT
TRANSPORTED BY GLACIERS
MANY FORMED 25,000 14,000 YRS AGO DURING
LAST ICE AGE
VAST ICE SHEET OVER
CANADA
GLACIERS FLOW AWAY FROM
ICE SHEET'S CENTER
18,000 YRS AGOSOUTHERMOST ADVANCE OF
GLACIER THAT FLOWED
THROUGH LAKE MICHIGAN
BASIN AND INTO NE ILLINOIS
SINCE THEN, ICE MELTED
BACK
QuickTime™ and a
Photo decompressor
are needed to see this picture.
MAXIMUM
EXTENT OF
GLACIATION
LAST
2 MILLION
YEARS
Davidson 14.15
Earth’s orbit changes
MILANKOVITCH CYCLES
Earth’s tilt changes
ECCENTRICITY, TILT, & PRECESSION CAUSE VARIATIONS IN SUNLIGHT (UP TO
ABOUT 5% AT HIGHER LATITUDES), SO CLIMATE VARIES BETWEEN WARMER AND
COLDER PERIODS.
COLDER WINTERS, MORE ICE ACCUMULATES, CAN START ICE AGE
OTHER FACTORS MAY ACT INCLUDING MOUNTAIN UPLIFT (HIMALAYA)
GLACIERS- THICK ICE, LASTS ALL YEAR; RECRYSTALLIZED SNOW MOVES
DOWNSLOPE BY GRAVITY OR RADIALLY OUTWARD BY ITS OWN WEIGHT
Robeson Glacier, Canada
GLACIERS ERODE &
DEPOSIT SEDIMENT - TILL
ADVANCING GLACIERS SLOWLY PUSH
EARTH & ROCK FORWARD
DEPOSIT THESE MATERIALS WHEN
GLACIERS MELT (RETREAT)
TILL - DEBRIS DEPOSITS, POORLY
SORTED FORM CHARACTERISTIC
LANDFORMS
END MORAINES
TILL DEPOSITS AT GLACIER
MARGIN
Sheridan Road,
Winnetka
Glencoe Beach
Glacial Park,
McHenry
Palos Park
Kettle Morraine
State Forest, WI
DRUMLINS
ROUNDED & ELONGATED HILL OF
GLACIAL TILL
BUILT UNDER ICE MARGINS
SHAPED BY GLACIERS FLOW
BLUNT NOSE IN DIRECTION FROM
WHICH ICE CAME & GENTLE SLOPE
TAPERED IN OTHER DIRECTION
ESKERS
LONG SAND & GRAVEL RIDGES
LEFT BY SEDIMENT IN
MELTWATER TUNNELS UNDER
GLACIER
VOLO BOG (McHENRY, IL)A KETTLE LAKE
FORMED 15,000 YEARS AGO
WITH GLACIER'S RETREAT
LEFTOVER LARGE BLOCKS
OF ICE ON GROUND
MELTS AS CLIMATE WARMS
FORMS KETTLE-HOLE
DEPRESSION
EVENTUALLY FILLS
RETREATING
GLACIERS; MUCH
STILL UNDER ICE
ILLINOIS 16,000 YRS AGO
RECENTLY
DEGLACIATED
AREAS COVERED
WITH BARE
SHEETS OF TILL
& SLOWLY
REVEGETATED
LARGE LAKES
WHERE
MORRAINES DAM
WATER COMING
OFF MELTING
GLACIERS
LAKES, MARSHES,
AND BOGS
COMMON
COOLER CLIMATE- DIFFERENT
PLANTS AND ANIMALS THAN TODAY
CHEMICAL SEDIMENTS: CRYSTALLIZED FROM WATER WHEN THEIR
CONCENTRATION EXCEEDS THAT WHICH CAN BE DISSOLVED (SOLUBLE)
IN WATER
EVAPORITES - SALTS OF
SODIUM, CALCIUM,
MAGNESIUM, POTASSIUM
DEPOSITED AS DESERT LAKES,
SEAS DRY UP.
EXAMPLESDEAD SEA
BONNEVILLE SALT FLATS
(GREAT SALT LAKE) REMAIN
FROM HUGE LAKE DURING ICE
AGES
MEDITERRANEAN (6 MYR AGO)
GREAT SALT LAKE - UTAH
LATEST OF LAKES THAT EXISTED
OFF AND ON FOR PAST 15 MYRS.
NO OUTLET BECAUSE AT BOTTOM
OF A BASIN. FRESH WATER
ENTERING FROM RIVERS CAN ONLY
EXIT BY EVAPORATION OR SEEPAGE
INTO DEEP GROUNDWATER LAYERS.
CURRENT CLIMATE OF HIGH
EVAPORATION AND LOW INPUT OF
FRESH WATER GIVES SALINE LAKE.
SALT WATERS’ MAJOR ELEMENTS:
SODIUM, MAGNESIUM, POTASSIUM,
CHLORIDE, AND SULFATE.
MAJOR MINERAL INDUSTRY
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
5-6 million years ago the
Mediterranean became
isolated from the Atlantic
Ocean, causing the sea
water to evaporate, and
leaving immense driedup basins, shown by a
large accumulation of
salt deposits sandwiched
between deep-water
marine sediments.
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
METAMORPHIC ROCKS- FROM ALTERATION OF PRE-EXISTING ROCKS
BY HEAT, PRESSURE, & CHEMICAL REACTIONS
CAN INVOLVE CHANGES IN
MINERALOGY, TEXTURE, &
CHEMICAL COMPOSITION
PRESSURE & TEMPERATURE
INCREASE WITH DEPTH
ALTHOUGH SHALLOW BURIAL
CAN PRODUCE LITHIFICATION &
DIAGENESIS OF SEDIMENT INTO
SEDIMENTARY ROCK, ONLY
PLATE TECTONIC PROCESSES
CAN CAUSE PRESSURES AND
TEMPERATURES HIGH ENOUGH
TO PRODUCE METAMORPHIC
ROCKS
METAMORPHIC ROCKS INDICATE
TEMPERATURE & PRESSURE
CONDITIONS UNDER WHICH THEY
FORMED
Davidson 4.26
METAMORPHIC ROCKS:
MARBLE
HEAT AND PRESSURE
METAMORPHOSE
LIMESTONE INTO
MARBLE
Metamorphic rocks
formed by increasing
pressure/temperature on
a mudstone to
slate,
then schist,
then gneiss,
then remelted &
recrystallized
Davidson 4.26
INTERNAL ENERGY
(HEAT) FROM EARTH
ACTS VIA PLATE
TECTONICS TO CAUSE
VOLCANISM &
MOUNTAIN BUILDING
EXTERNAL ENERGY
FROM SUN CAUSES
WEATHER, THUS
WEATHERING,
EROSION,
TRANSPORTATION, &
DEPOSITION OF
SEDIMENTS
ROCKS BURIED,
METAMORPHOSED,
MELTED & UPLIFTED BY
TECTONIC PROCESSES
Davidson 4.30
THE ROCK CYCLEINTERCONNECTIONS BETWEEN
ROCK-FORMING PROCESSES