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