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Understanding Earth Processes & the Formation of ROCKS!
Understanding Earth Processes & the Formation of ROCKS!
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Molten = melted rock Circulating heat currents Hot, liquid rock circulating in currents within Earth cause continental and oceanic plates to move
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Ocean floors and continents move like huge puzzle pieces…
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This super-continent was called Pangea
Continental plates were once very close together This super-continent was called Pangea
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Earth is made up of… 1/3 land & 2/3 ocean
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LAVA and volcanic eruption!
When one plate slides under another, volcanoes form Heat and pressure from the plate sliding under another cause molten rock to make its way out of the earth’s surface… LAVA and volcanic eruption!
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One plate sliding under another
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Two plates colliding together, causing the land to buckle, would give us what?
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Mountains!
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Mountains erode (break down) continuously…
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Gravity takes eroded rock pieces (sediment) downward towards water…
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Sediment makes it’s way to the sea…
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Erosion occurs from the wind as well…
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…and also by water
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Earth Processes give us…
Plate movement, Erosion, and all Earth Processes give us…
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Rocks!
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Diversity of ROCKS! Natural forces at work! Combinations of temperature, pressure, and chemical interactions within earth and on its surface gives us a huge diversity of rocks!
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Rocks! Made up of a mineral or a mixture of minerals
May also contain sediments and fossil remains of plants and animals They are the result of natural forces at work on our planet The study of rocks is called petrology
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The elements oxygen, silicon, aluminum, iron, magnesium, calcium, potassium, and sodium make up
99 percent of all minerals on Earth.
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The largest topaz crystal was found in Brazil in 1940
The largest topaz crystal was found in Brazil in It weighs 596 pounds. It is on display in the American Museum of Natural History in New York.
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Rock made up of sediment and fossils!
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Rock made up of one type of mineral
Quartzite – made up of the mineral quartz The most common mineral on earth is quartz.
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ROCKS are the records to our planet’s past!
They indicate where rivers have flowed Where huge inland seas were located What organisms lived in those seas Where glaciers covered land
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Dry river beds…only sediment and rocks remain!
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Rocks indicate where water levels once were…
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All rocks fall into one of 3 basic groups:
Basic Rock Types All rocks fall into one of 3 basic groups: 1. Igneous 2. Sedimentary 3. Metamorphic
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Igneous Rocks Form from the cooling of liquid rock
Igneous means “fire” Form from the cooling of liquid rock (magma) that came up from deep within the earth. It is the melting and solidification of metamorphic rocks! Igneous rock is the most common material of the earth’s crust!
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Igneous Rocks: Often hidden by sedimentary rock
Can be intrusive or extrusive igneous rock If recrystallization and solidification occurred below the earth’s surface (such as the formation of granite), than the rock is intrusive If the rock formed on the earth’s surface from cooling of volcanic lava (such as obsidian and basalt), than the rock is extrusive
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Igneous Rocks: If rock formed from a slow cooling, the rock will contain coarse-textured minerals (Example = granite) If rock formed from a fast cooling, the rock will contain fine-textured minerals (Example = basalt) If rock contains a high amount of silica, it will be light in color and weight, and be known as acidic If rock contains high amounts of iron and magnesium, it will be dark-colored and heavy, and be known as basic
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Most common extrusive and basic igneous rock
Basalt Most common extrusive and basic igneous rock
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Most abundant of all igneous rocks
Granite Most abundant of all igneous rocks
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Gabbro
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Rhyolite
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Scoria
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Obsidian Looks like shiny black glass as a result of very fast cooling of volcanic lava
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Porous (has many holes) and floats on water!
Pumice Porous (has many holes) and floats on water!
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Sedimentary Rocks Form from the burial and cementing of layers of sediment broken off of other rock types and deposited in water. Weathering and erosion can be caused by wind, waves, gravity, or water. Rivers carry sediment for long distances.
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Rock formation from years of wind erosion…
Sediment that was swept away eventually became sedimentary rocks!
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Sediment: Sand Gravel Mud Clay
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Conglomerate or Breccia (depends on rounding) Cobble
Name of Particle Size Range Loose Sediment Consolidated Rock Boulder >256 mm Gravel Conglomerate or Breccia (depends on rounding) Cobble 64 – 256 mm Pebble mm Sand 1/16 –2 mm Sandstone Silt 1/ /16 mm Siltstone Clay <1/256 mm Claystone, mudstone, and shale
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Compaction from the weight of accumulating sediment results in layers that become hardened and turn to sedimentary rocks!
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Most sedimentary rocks form under water.
Most of the earth has been covered by water some time in the past. 70% of the earth is covered by water now. So sedimentary rocks are common all over the world. Sedimentary rocks are often rich in fossils. Many sedimentary rocks may have cross-bedding, mud cracks, worm burrows, raindrop impressions. 70% of rocks found on Earth are sedimentary.
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Two Types of Sedimentary Rocks!
Rocks formed from sediment (sand, silt, clay, or mud) or clasts (pieces) of rock are known as clastic sedimentary rocks Rocks formed from processes known as chemical precipitation or organic activity are known as non-clastic sedimentary rocks
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Shale Nonclastic (clay)
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Conglomerate Clastic (rounded pebbles)
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Sandstone Clastic (sand)
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Limestone Non-Clastic (calcium carbonate precipitate)
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Bituminous Coal Non-Clastic (buried peat moss material)
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Peat that gets buried over time and compressed deep into the earth eventually gives us bituminous coal. Bituminous coal is carbon-rich and is an excellent source of energy. Humans burn coal to release that energy in the form of heat.
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Gypsum Non-Clastic sedimentary rock that can be scratched with your fingernail!
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Metamorphic Rocks Form from pressure and extreme temperatures changing the chemistry of igneous and sedimentary rocks that got buried into the earth over time.
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Metamorphosis Complete change of character, appearance, or condition.
Involves heat, pressure, and chemical action Process can occur more than once Results in the recrystallization of original rock (sedimentary or igneous) and a different mineral composition
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Limestone metamorphosed to marble!
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Sandstone metamorphosed to quartzite!
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Shale metamorphosed to slate!
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Gabbro metamorphosed to schist!
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Many metamorphic rocks contain flat minerals such as mica and needle-like minerals such as hornblende Mica Hornblende
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These rocks can split into thin sheets!
Slate These rocks can split into thin sheets!
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Can be polished and made into kitchen countertops!
Marble Can be polished and made into kitchen countertops!
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Schist
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Gneiss What a nice rock!
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Gneiss The oldest known rock lies in Canada. The Acasta gneiss, a metamorphic rock, is 3.96 billion years old.
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Rock Cycle is a sequence of processes or events involving the formation, alteration, destruction, and reformation of rocks
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Taj Mahul in India Built between 1632 and 1654 is made entirely out of marble!
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Up to 100,000 tons of rock a year fall to earth from space
Up to 100,000 tons of rock a year fall to earth from space. The largest meteorite in the world lies in the ground in Africa and weighs more than 60 tons.
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A 2. 2 lb rock collected from the moon during the Apollo 16 mission
A 2.2 lb rock collected from the moon during the Apollo 16 mission. This rock formed when older moon rocks were fragmented and and then fused back together by a meteorite impact about 3.9 bya. The shiny black material on the side is impact-generated glass.
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The Importance of Rocks and Minerals
Name Type of Rock Use Basalt Igneous Used in road building materials Calcite Mineral Used in cements and mortars and the production of lime Granite Used for buildings, monuments, and tombstones Marble Metamorphic Used in building, floors, tile in bathrooms Obsidian Used in making arrowheads and knives Pumice Used in scouring, scrubbing, and polishing materials Quartz Used in making glass, electrical components, and optical lenses Sanstone Sedimentary Used in the building industry for houses Slate Used for roofs, chalkboards, and patio walks
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Landforms Part or area of the Earth’s surface that has a distinctive shape or topography
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Weathering is a series of natural processes, both physical and chemical, that act to change exposed rock into mineral and rock particles and chemical compounds in solution.
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Independent Variable Dependent Variable
is the one variable that is changed on purpose in an experiment. Dependent Variable is the outcome that is being measured in an experiment.
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