Geology Summer class midterm

Himalayas boundary

convergent

San Andreas Fault boundary

transform boundary

Hot Spots

places where molten material from the mantle reaches the lithosphere

How are minerals created? Think on the atomic level.

Minerals are created through crystallization from cooling magma or precipitation from solutions

Fracture/Cleavage:

Cleavage is the tendency to break along planes of weakness

Cubic fracture

a type of fracture in minerals where the breakage surfaces are typically flat and form right angles.

Rhombohedral facture

a type of fracture in minerals where the breakage surfaces are inclined at an angle that is not 90 degrees.

Conchoidal fracture vs random fracture

Conchoidal Fracture:
Smooth, curved breakage surfaces
Resembles the shape of a clamshell
Typically seen in minerals like quartz

Random Fracture:
Irregular and jagged breakage patterns
Lacks a specific shape or direction
Common in minerals with complex crystal structure

Crystal facets:

Definition: Flat surfaces on a crystal that reflect the internal arrangement of atoms.

Cleavage planes:

Definition: Planes along which minerals tend to break when subjected to stress due to weak atomic bonds.

Sedimentary rocks:

Definition: Rocks formed from the accumulation and lithification of sediments.

Igneous rocks:

Definition: Rocks formed from the solidification of molten magma or lava.

Metamorphic rocks:

Definition: Rocks formed from the alteration of existing rocks due to heat and pressure.

Viscosity

influenced by silica content and temperature

What is the viscosity of water compared to magma?

The viscosity of water is much lower than that of magma. At room temperature, water has a viscosity of about 0.001 Pa.s, while magma can have viscosities ranging from 10^2 Pa.s to 10^10 Pa.s.

Bowen's reaction Series

explains the order of crystallization of minerals

shield volcano

a wide, gently sloping mountain made of layers of lava and formed by quiet eruptions

Cinder Cone

A steep, cone-shaped hill or small mountain made of volcanic ash, cinders, and bombs piled up around a volcano's opening

Composite (Stratovolcano)

a large, cone-shaped subaerial volcano consisting of alternating layers of lava and tephra

Pillow lavas:

basaltic lava that solidifies in an underwater environment and develops a structure that resembles a pile of pillows

Pahoehoe:

A hot, fast-moving type of lava that hardens to form smooth, ropelike coils

AA Flows:

a type of lava flow that has a jagged, blocky surface

cinders debris

Definition: Small volcanic rock fragments measuring 2-64 mm in diameter.

pyroclastic debris

Definition: Mix of fragmented volcanic material, including ash, pumice, and larger rocks.

What is a lahar?

destructive mudflow on the slopes of a volcano. It is typically composed of volcanic materials, such as ash and rock fragments, mixed with water from heavy rains, a lake overflow, or melting snow and ice on a volcano.

Caldera

Large crater formed by the collapse of a volcano

Kilauea Volcano

This Hawaiian shield volcano has been erupting continuously since 1983 (USGS image).

Mt. St Helens volcano

is an active stratovolcano located in Washington State, USA. It is known for its catastrophic eruption on May 18, 1980, which resulted in the loss of lives and massive destruction of the surrounding area.

Yellowstone volcano

supervolcano located in Yellowstone National Park in the United States. It is known for its geothermal features, including geysers and hot springs.

dike

is a vertical or near-vertical sheet-like intrusion of magma that cuts across the layers of pre-existing rock.

A sill

on the other hand, is a tabular sheet-like intrusion of magma that is parallel to the layering of the pre-existing rock.

Where in the world is most volcanic activity? Why are they found here?

Most volcanic activity on Earth occurs at tectonic plate boundaries, specifically at constructive (divergent) and destructive (convergent) plate margins.

Felsic

Describes magma or igneous rock that is rich in feldspars and silica and that is generally light in color.

Mafic

igneous rocks with a high content of magnesium and iron, and a relatively low silica content.
commonly associated with oceanic crust, volcanic islands, and hotspots

Ultramafic

igneous rock composed mainly of iron and magnesium-rich minerals

Sedimentary Rock

A type of rock that forms when particles from other rocks or the remains of plants and animals are pressed and cemented together

Precipitation

a process where water, in the form of rain or snow, chemically weathers rocks over time

Lithification

The process that converts sediments into solid rock by compaction or cementation.

Evaporation

a process where water evaporates from rocks, leaving behind dissolved minerals that can crystallize and cause physical stress on the rock surface.

Angularity vs rounding

refers to the sharpness or degree of sharp angles in the edges and corners of sedimentary particles, while rounding refers to the smoothness of those edges and corners.

Definition: Smoothness of edges and corners of sedimentary particles.

Sorting

particles are separated based on their size and density.

Deposition:

Sorted sediments settle out of the transporting medium.
Coarse particles settle first, followed by finer particles.
Deposition occurs when the transporting energy decreases.

Metamorphic rock

A type of rock that forms from an existing rock that is changed by heat, pressure, or chemical reactions.

What are the protoliths?

the original rock type from which a metamorphic or sedimentary rock is derived.

Sedimentary protoliths

These are rocks formed by the deposition and subsequent cementation of mineral or organic particles on the Earth's surface.

Metamorphic protoliths:

These are rocks that have been transformed due to heat, pressure, or chemically active fluids, but have not melted.

Foliation

An arrangement of minerals in flat or wavy parallel bands.

Non-foliated rock types

rock types are a classification of metamorphic rocks that lack a layered or banded structure typically associated with foliated rocks.

Which rock type is a product of high-grade metamorphism?

common rock type produced by high-grade metamorphism. It is characterized by its distinct banding and alternating layers of light and dark minerals, which are the result of intense heat and pressure that recrystallize the rock's original minerals

Regional metamorphism

formation of metamorphic rock bodies that are hundreds of square kilometers in size

Thermal/contact metamorphism

metamorphism caused by heat conducted into country rock from an igneous intrusion

Rock Cycle

Melting & solidification, Weathering, Erosion & Lithification, Heat, Pressure & Fluids

Processes needed for each rock type

i) Melting & solidification(crystallization)
ii) Weathering, erosion, and lithification
iii) Heat, pressure and fluids

Igneous protoliths:

These are rocks that have solidified from a molten state, either intrusively (forming within the Earth's crust) or extrusively (erupting onto the surface).