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CRUCIAL FACTORS: SOURCE ROCK FROM WHICH SEDIMENT DERIVED TRANSPORT MECHANISM (WIND, WATER, ICE) SITE OF DEPOSITION (RIVER, LAKE, OCEAN, DESERT) PLATE TECTONIC.

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Presentation on theme: "CRUCIAL FACTORS: SOURCE ROCK FROM WHICH SEDIMENT DERIVED TRANSPORT MECHANISM (WIND, WATER, ICE) SITE OF DEPOSITION (RIVER, LAKE, OCEAN, DESERT) PLATE TECTONIC."— Presentation transcript:

1 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 ROCKS-MINERAL OR ROCK FRAGMENTS OR MATERIAL OF ORGANIC ORIGIN ARE ERODED OR DISSOLVED AND THEN DEPOSITED IN LAYERS AT EARTH'S SURFACE

2 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)

3 Size and shape of sedimentary grains reflects transportation history. Davidson 4.20 Beach sand

4 Davidson 4.19 SEDIMENTARY ROCK TYPES Large grains indicate transport and deposit by strong currents: mountain streams, beaches with large waves, or glacial melt streams Deposited by gentle currents, so small particles settle out of the water: deep ocean, coasts with weak tides Deposited by moderate currents that removed finer sediment: rivers, coasts with moderate waves, wind-produced dunes.

5 COMPACTION, LITHIFICATION, DIAGENESIS UNCONSOLIDATED SEDIMENT TURNS INTO HARD SEDIMENTARY ROCKS Davidson 4.25 Similar to snow turning to ice

6 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

7 MIDWEST HAS FEATURES FORMED BY SEDIMENT TRANSPORTED BY GLACIERS MANY FORMED 25, ,000 YRS AGO DURING LAST ICE AGE VAST ICE SHEET OVER CANADA GLACIERS FLOW AWAY FROM ICE SHEET'S CENTER 18,000 YRS AGO- SOUTHERMOST ADVANCE OF GLACIER THAT FLOWED THROUGH LAKE MICHIGAN BASIN AND INTO NE ILLINOIS SINCE THEN, ICE MELTED BACK

8 MAXIMUM EXTENT OF GLACIATION LAST 2 MILLION YEARS Davidson 14.15

9 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) MILANKOVITCH CYCLES Earth’s orbit changes Earth’s tilt changes

10 GLACIERS- THICK ICE, LASTS ALL YEAR; RECRYSTALLIZED SNOW MOVES DOWNSLOPE BY GRAVITY OR RADIALLY OUTWARD BY ITS OWN WEIGHT Robeson Glacier, Canada

11 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

12 END MORAINES TILL DEPOSITS AT GLACIER MARGIN Sheridan Road, Winnetka Glencoe Beach Glacial Park, McHenry Palos Park Kettle Morraine State Forest, WI

13 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

14 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

15 RETREATING GLACIERS; MUCH STILL UNDER ICE 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 ILLINOIS 16,000 YRS AGO

16 EVAPORITES - SALTS OF SODIUM, CALCIUM, MAGNESIUM, POTASSIUM DEPOSITED AS DESERT LAKES, SEAS DRY UP. EXAMPLES- DEAD SEA BONNEVILLE SALT FLATS (GREAT SALT LAKE) REMAIN FROM HUGE LAKE DURING ICE AGES MEDITERRANEAN (6 MYR AGO) CHEMICAL SEDIMENTS: CRYSTALLIZED FROM WATER WHEN THEIR CONCENTRATION EXCEEDS THAT WHICH CAN BE DISSOLVED (SOLUBLE) IN WATER

17 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

18 5-6 million years ago the Mediterranean became isolated from the Atlantic Ocean, causing the sea water to evaporate, and leaving immense dried- up basins, shown by a large accumulation of salt deposits sandwiched between deep-water marine sediments.

19 CAN INVOLVE CHANGES IN MINERALOGY, TEXTURE, & CHEMICAL COMPOSITION 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 METAMORPHIC ROCKS- FROM ALTERATION OF PRE-EXISTING ROCKS BY HEAT, PRESSURE, & CHEMICAL REACTIONS Davidson 4.26 PRESSURE & TEMPERATURE INCREASE WITH DEPTH

20 METAMORPHIC ROCKS: MARBLE HEAT AND PRESSURE METAMORPHOSE LIMESTONE INTO MARBLE

21 Metamorphic rocks formed by increasing pressure/temperature on a mudstone to slate, then schist, then gneiss, then remelted & recrystallized Davidson 4.26

22 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 THE ROCK CYCLE- INTERCONNECTIONS BETWEEN ROCK-FORMING PROCESSES Davidson 4.30

23 Metamorphic rocks may develop new textures as mineral grains change, including size & orientation due to pressures & temperatures

24 CONTACT METAMORPHISM- CHANGES WITH DISTANCE FROM HEAT SOURCE

25 Metamorphic minerals depend on temperature & pressure conditions

26 LITHIFICATION & DIAGENESIS UNCONSOLIDATED SEDIMENT TURNS INTO HARD SEDIMENTARY ROCKS LITHIFICATION : ROCK FORMS AS SEDIMENT IS COMPACTED BY BURIAL SO WATER OR AIR ARE FORCED OUT OF THE PORES (SPACES) BETWEEN GRAINS >GRAINS ARE THEN CHEMICALLY CEMENTED TOGETHER BY MINERALS DEPOSITED BY FLUIDS IN PORES DIAGENESIS: MINERAL CHANGES OCCUR DUE TO INCREASING TEMPERATURE AND PRESSURE FOR EXAMPLE, FLINT IS CHEMICALLY PRECIPITATED SiO 2 CHANGED TO CRYSTALLINE ROCK

27 CLASTIC SEDIMENT: CONGLOMERATE Rounded pebble-sized or large fragments in matrix of silt or sand. Large sediment sizes indicate transport and deposition by strong currents: mountain streams, rocky beaches with large waves, or glacial meltwater streams Rounded clasts suggest transport over long distances.

28 CLASTIC SEDIMENT: SANDSTONE Mostly sand-size quartz grains bound by a cementing agent; individual grains are visible to naked eye Abundant (25% sedimentary rocks) Deposited from moderate currents that removed the finer sediment: rivers, coasts with moderate wave activity, wind- produced dunes.

29 CLASTIC SEDIMENT: SHALE fine-grained layered rock resulting from compaction of clay, mud, or silt generally black but can be red or green due to different minerals breaks along bedding into thin planar pieces Deposited by gentle currents, so small particles settle out of the water: deep ocean, coastal areas with weak tides, rivers

30 BIOCHEMICAL SEDIMENTS: THE SKELETONS OF MARINE ORGANISMS SUCH AS SHELL OR CORAL ACCUMULATE AND THEN CAN BE BROKEN UP, TRANSPORTED, AND DEPOSITED LIMESTONE FORMED FROM CALCIUM CARBONATE SHELLS CHALK (CLIFFS OF DOVER) IS A KIND OF LIMESTONE

31 PEAT / COAL FORMED FROM ACCUMULATION AND COMPACTION OF DEAD PLANT MATERIAL IN SWAMPS AND BOGS (FOSSIL FUEL) NEARLY PURE CARBON SHALLOW BURIAL CONVERTS TO PEAT DEEPER (HIGHER PRESSURE AND TEMPERATURE) CONVERTS TO COAL

32 Grand Canyon Cross Section


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