Bruce Sherman ESSC 101 Exam 2
What are Igneous intrusive (plutonic) rocks?
magma that solidifies beneath surfaces
What are ways to change magma chemistry?
Assimilation- hot magma may melt some of the country rock and assimilate newly molten material in the magma Mixing- one encounters the other on the way to the surface
What percentage of rocks are sedimentary?
75%
The most distinctive feature of the E horizon is
its lack of both organic matter and soluble minerals
The primary difference between magma and lava is that
one is below the ground, the other is above the ground
Chemical
precipitated from solution or remains of biologic organisms; derived from material that was once in solution and precipiatated
Cementation
precipitation around sediment grains binds them into a firm coherent rock
How are igneous rocks formed?
-By cooling of magma or lava -Ions slow down, attract, and begin mineral formation
Igneous Rocks
-Rock that has solidified from magma Examples: Basalt (extrusive) Granite (intrusive)
What are the most common identifying features of a sedimentary rock?
-Strata -Bedding Planes -Fossils
Metamorphic Rocks
-changed form rocks -produced from preexisting igneous, sedimentary, or metamorphic rocks
Factors Affecting Metamorphic Rock
-composition of parent rock -temperature and pressure during metamorphism -tectonic forces -effects of fluids (H2O
What are Igneous extrusive (volcanic) rocks?
-formed at the surface
How are gypsum and rock salt formed?
-formed from the evaporation of seawater or a saline lake
Examples and Characteristics of Intrusive rocks:
-granite (feldspar and quartz) -coarse grained due to magma crystallizing slowly underground
Examples of Chemical
-limestone, quartz, gypsum, coal
Frost Action
-most important weathering process -mechanical affect on freezing water on rocks commonly occurs as frost wedging or heaving
Igneous Rocks can be divided into 3 textures
1. Crystalline Rocks- interlocking crystals, grain or crystal size 2. Glassy Rocks- composed primarily of class 3. Fragmental Rocks- composed of fragments of igneous material
Types of Sedimentary Rocks
1. Detrital 2. Chemical 3. Organic
Types of Metamorphism
Contact- high temperature is the dominant factor Regional- takes place at considerable depth underground
Sedimentary Rocks
Formed from eroded mineral grains, minerals precipitated at a low temperature solution, or consolidated of the organic remains
Examples of Sediment
Gravel, Sand, Silt, Clay
What are the four main types of sediment when referring to size?
Gravel, Sand, Silt, Clay
Ophiolite
Igneous rocks in oceanic crust
The three basic groups of rocks
Igneous, Sedimentary, Metemorphic
Soil
Incredibly valuable resource -loose unconsolidated material that covers most of Earth's land surface
Strata
Layers of rock.
What is the most abundant chemical rock?
Limestone
How do we classify Igneous rocks?
Named and based on their texture and chemical composition. The texture will tell you where the rock was formed: beneath surface or on the surface. -By its color
Horizon Layers
O-Organic matter A-Organic matter mixed with minerals E-little organic material B-zone of accumulation C-partially altered parent material
What forms in organic rich sedimentary rocks?
Oil and natural gas.
What is the last mineral to form according to Bowen's reaction series?
Quartz
Organic
Rocks composed of organic carbon compounds.
Examples of Detrital Rocks
Sandstone (cementation of sand grains), Shale (splits into layers), Conglomerate (rounded gravel)
Evaporites
Type of chemical rock that is formed from crystals that precipitate during evaporation of water.
What is Bowen's reaction series?
Shows the sequence in which minerals crystallize in a cooling basaltic magma.
Solum
True soil (OAEB)
The term "foliation" in metamorphic rocks refers to
a consistent orientation of the mineral grains perpendicular to the direction of greatest pressure
Water facilitates metamorphic reactions by
aiding movement of atoms and ions
Chemical Weathering
alters the internal structures of minerals by removing or adding elements; most important agent is water
Metamorphic Rocks
always stay in a solid state.
Rocks and minerals are most stable when they:
are in the environment in which they formed
Mechanical weathering can:
change the size and shape of rock structures
What controls soil formation?
climate, plants, and animals
Compaction
compacts loose sediment tightly together
Topsoil
composed of O and A
Residual Soil
developed on bedrock (parent material)
Bedding
dries of visible layers within a rock
Sedimentary structures such as graded bedding, cross-bedding, and ripple marks are formed:
during or after deposition, but before lithification
Detritial Rocks
formed from weathering and eroded remains of bedrock -sediments made up of mineral grains or parts of other rocks; material is solid
Water performs all of the following functions in chemical weathering EXCEPT
freezes in the cracks, facilitating frost wedging
As pressure increases, the melting-point of a rock increases
increases
As the rate of cooling decreases, particle size in an igneous rock
increases
Sediment
loose, solid particles of mineral that originate from: 1. weathering and erosion of preexisting rocks 2. precipitation of solution
The rock that results from the metamorphism of relatively pure limestone is
marble
Metamorphic rocks form through all of the following processes EXCEPT
melting and recrystallizing
Magma
molten rock and dissolved gas; forms from decompression melting at ocean ridges or partial melting of subducting slabs
Lava
molten rock material which gas has mostly escaped; magma brought to the surface
Transported Soil
parent material has been carried form elsewhere and deposited.
Graded beds are commonly formed by
particles settling at different rates
Plutonic rocks are characterized by which type of texture
phaneritic
Lithification
processes that convert loose sediment into sedimentary rock
What makes mud?
silt and clay
Metamorphism
takes place when preexisting rocks are subjected to temperatures and pressures unlike those in which it formed. -Changes to rocks that take place in Earth's interior.
The two properties used most to classify igneous rocks are:
texture and mineral composition
Mechanical Weatherin
the breaking of rocks into smaller pieces -change in rock is PHYSICAL example: water freezing
Sedimentary structures allow a geologist to determine
the depositional environment of detrital sediments
The term "texture" refers to
the size and shape of the mineral components
Detrital sediment texture is identified on the basis of:
the size, shape, and arrangement of the particles
In general, chemical weathering would occur most rapidly in a:
warm, moist climate
The single most important factor controlling the rate of chemical weathering is
water
The first criterion used to classify metamorphic rocks is:
whether it is foliated or nonfoliated