62 terms

Rocks

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Crushed stone (rock)
Used as a construction material
Rock Cycle
Process by which all rocks are formed and transformed
Major rock-forming minerals
Quartz
Feldspar
Mica
Calcite
Texture
The size, shapes, and positions of grains that make up the rock
Igneous rocks
Formed from molten rock that cools and hardens below or on Earth's surface, classified as intrusive or extrusive
Sedimentary rocks
Formed by rock fragments or organic matter being bound together, or by chemical precipitation; classified as clastic or non-clastic
Metamorphic rocks
Formed when any rock is changed by the effects of heat or pressure; classified as foliated or non-foliated
Sediment
Loose materials like rock fragments, mineral grains, and bits of plants and animal remain
Classification of Sedimentary Rocks
Classified by composition and how they are formed; classified as detrital (clastic); chemical, or organic (non-clastic)
Compaction
Sedimentary rocks formed by being pressed together
Cementation
Sedimentary rocks formed by being glued together
Sedimentary rocks form as ...
Layers.
Oldest layers are at the bottom, because they are deposited first.
Weathering
Process that breaks rocks into smaller pieces
Erosion
Moves sediments to a new location
Deposition
Leaves sediments in a new location
Pressure
Pushes upper layers down on lower layers
Sediment Size
Clay < Silt < Sand < Gravel
Clastic/Detrital Sedimentary Rocks
Sedimentary rocks made from the broken fragments of other rocks
Chemical Sedimentary Rocks
Sedimentary rocks that form when dissolved minerals come out of solution
Mineral deposits
Form when seas or lakes evaporate; deposits of minerals form sediments and rocks
Limestone bedrock
Indicates the area used to be covered in a sea/ocean
Karst topography
Topography characterized by limestone bedrock, which leads to the formation of caves and sinkholes, common in the Valley & Ridge Province
Coal
Organic sedimentary rock formed when pieces of dead plants are buried and compacted for millions of years in swamps; found in the Appalachian Plateau
Fossil-rich limestone
Organic sedimentary rock made from the remains of once-living marine organisms
Temperature and pressure ________ with depth in the Earth
increase
Because of heat and pressure, rocks don't melt, but _________ and ____________.
dissolve and recrystallize
Minerals _________ atoms with surrounding minerals and form new, bigger minerals
exchange
What two processes make metamorphic rocks?
Heat and pressure
Water with diissolved elements and compounds can react chemically with a rock and change its _________.
composition
Rock surrounding a hot magma body reacts with hot fluids, forming metamorphic rock. This is called what?
Contact metamorphism
Contact metamorphism occurs when the minerals and texture of rock change when they are exposed to what?
Pressure and temperature of a body of magma
What is it called when a rock changes due to contact with a body of intruding magma?
Contact metamorphism
Texture of Metamorphic Rocks
Foliated or Unfoliated
Foliated texture
Banded; mineral grains flatten and line up in parallel layers or bands
Unfoliated texture
Nonfoliated; mineral grains grow and rearrange but do not form layers
Examples of foliated rocks
Slate, schist, gneiss
Slate
Foliated metamorphic rock; forms from sedimentary rock shale; slate separates easily along foliation layers
Schist
Foliated metamorphic rock; forms from sedimentary rock shale
Gneiss
Foliated metamorphic rock; forms from igneous rock granite; forms alternating light and dark bands
Unfoliated metamorphic rocks do not have what?
Bands/lines/foliations
Examples of unfoliated metamorphic rocks
Marble, quartzite
Marble
Unfoliated metamorphic rock; forms from sedimentary rock limestone
Quartzite
Unfoliated metamorphic rock; forms from sedimentary rock sandstone
Magma is less _______ than surrounding rocks, so it forces its way upward to the surface.
dense
Pressure from the build up of ______ inside of a volcano can force magma to the surface during an eruption.
gases
Magma that reaches the surface is known as ______.
magma
Rocks that form from magma below the surface of the Earth
intrusive igneous rocks
Intrusive igneous rocks take a _______ time to form.
long
Intrusive igneous rocks have ______ crystals and a ______ texture.
large; coarse
Why do intrusive igneous rocks have a coarse texture?
They form from magma that cools slowly, forming large individual mineral grains and crystals.
Extrusive igneous rocks
Formed as lava cools on the surface of the outside
Extrusive=exterior= ?
Outside
Extrusive rocks are also called what?
Volcanic rock; named after Vulcan, the Roman god of destructive fire
Lava cools very quickly when it is exposed to ______ and/or _______.
air; water
When lava cools quickly, extrusive rocks form very ______ crystals.
small
Granite
Intrusive igneous rock made up of feldspar, quartz, and mica
Obsidian
Volcanic glass; cooling occurs so rapidly that no crystals have time to form
Is obsidian an intrusive or extrusive igneous rock, and how do you know?
Extrusive, because it has no crystals
Vesicles
Holes found in rocks that form because of bubbles that were present in lava or magma when it cooled
Pumice
Extrusive igneous rock with vesicles/holes
chemical weathering
The process in which rock is broken down by changes in its chemical makeup
physical weathering (mechanical weathering)
process that breaks down rocks and minerals into smaller pieces but does not involve any change in their composition