Geol1001 Exam 1

What is the Law of Uniformitarianism?

the processes that shape the Earth today are the same as those that have occurred in the past.

What is the process that formed Earth's layers?

differentiation, where denser materials sank to the center and lighter materials rose to form the crust.

What three materials were dated to provide evidence for the age of Earth?

zircon crystals, meteorites, and lunar samples

How is Earth's magnetic field generated?

the movement of molten iron and nickel in the outer core, which creates electric currents.

What is the Earth system?

geosphere, atmosphere, hydrosphere, biosphere, cryosphere

What are reservoirs in the Earth system?

storage locations for water and other materials within the Earth system, such as oceans, glaciers, and groundwater.

What are transport pathways in the Earth system?

routes through which materials and energy move between reservoirs, such as rivers, atmospheric currents, and ocean currents.

What is the hydrologic cycle?

the continuous movement of water through evaporation, condensation, precipitation, and runoff, involving various reservoirs and processes.

Define Plate Tectonics Theory.

the large-scale movement of the Earth's lithosphere, which is divided into tectonic plates that interact at their boundaries.

What evidence was proposed to explain the Continental Drift hypothesis?

the fit of continental coastlines, fossil similarities across continents, and geological similarities between continents.

Who proposed the Continental Drift hypothesis?

Alfred Wegener

Why was the Continental Drift hypothesis rejected?

a lack of a convincing mechanism to explain how continents could move.

What are the magnetic stripes on the seafloor?

patterns of alternating magnetic polarity formed by the cooling of magma at mid-ocean ridges.

What role does Earth's outer core play in the formation of magnetic patterns?

The movement of molten iron generates the Earth's magnetic field, which is recorded in the rocks as they cool.

How does the age of oceanic crust support sea floor spreading?

It increases with distance from mid-ocean ridges, supporting the idea that new crust is formed at these ridges and spreads outward.

How does the distribution of volcanism and earthquakes relate to plate tectonic boundaries?

Volcanism and earthquakes are concentrated along plate boundaries, where plates interact, leading to geological activity.

What is the Wilson Cycle?

the formation and breakup of supercontinents over geological time.

What are the mechanisms/drivers of plate tectonics?

slab pull, ridge push, and mantle convection.

At what scale do tectonic plates move on average in a year?

a few centimeters

What direct measurement is used to determine the direction and speed of plate movement?

GPS (Global Positioning System)

What are the requirements that a mineral must meet to be a true mineral?

naturally occurring, inorganic, solid, have a definite chemical composition, crystalline structure.

How does an atom become a cation or anion?

An atom becomes a cation by losing electrons (positively charged) and an anion by gaining electrons (negatively charged).

What is mineral cleavage?

the tendency of a mineral to break along flat, even surfaces, which is determined by its crystal structure.

What are common physical properties of minerals?

luster, color, streak, hardness, cleavage, and crystal shape/habit.

What is a silica tetrahedron?

a fundamental building block of silicate minerals, consisting of one silicon atom surrounded by four oxygen atoms.

What is the difference between mineral deposits and ore deposits?

Mineral deposits are naturally occurring concentrations of minerals, while ore deposits are mineral deposits that contain sufficient metal content to be economically viable for extraction.

Divergent boundaries

Plates move apart

Convergent boundaries

Plates come together

Transform boundaries

plates slide past each other

Normal fault

hanging wall moves downward relative to the footwall

reverse fault

Hanging wall moves upward relative to footwall.

Syncline fold

folds downward

anticline fold

folds upward

Ionic bonding

transfer of electrons

covalent bonding

sharing of electrons

metallic bonding

sharing of free electrons

Van der Waals Bonding

weak attractive force between atoms that have no electrons available for bonding

Hydrothermal ore deposits

form from hot, mineral-rich fluids

Magmatic Ore Deposits

form from cooling magma

Sedimentary Ore Deposits

form from accumulation of sediments

Isostasy

The balancing of the downward force of the crust and the upward force of the mantle.

Why does the age of oceanic crust, the thickness of sea floor sediment, and alternating strong and weak signals of the oceanic crust support sea floor spreading?

They support a dynamic system in which plates move apart, new crust is created, and old crust is subducted.

What are the major features associated with divergent boundaries?

mid-ocean ridges, rift valleys, and volcanic activity as new crust is formed.

What are the major features associated with convergent boundaries?

mountains, ocean trenches, volcanic arcs, and accretionary prisms due to the collision and subduction of tectonic plates.

How does magma form at subduction zones?

An oceanic plate is forced beneath a continental plate, causing the subducted plate to melt due to increased temperature and pressure, leading to volcanic activity.

How does magma form at divergent boundaries?

tectonic plates pull apart, reducing pressure on the mantle, which allows it to melt and rise to create new crust.

What are fault lines?

Fault lines are fractures in the Earth's crust where blocks of land have moved past each other, often associated with transform boundaries.

What are rift valleys?

Rift valleys are low-lying areas that form when tectonic plates pull apart, often found at divergent boundaries, but can also be influenced by transform boundary activity.

How does sea floor spreading and hot spot volcanic island chains provide evidence for plate movement?

Sea floor spreading occurs at mid-ocean ridges where tectonic plates diverge, creating new oceanic crust. Hot spot volcanic island chains form as tectonic plates move over a stationary hot spot in the mantle, leading to a series of volcanoes. The age and location of these islands provide evidence of the direction and speed of plate movement.

What is the formula for calculating the velocity of plate motion?

Velocity = Distance / Time.

What are hot spots?

volcanic regions thought to be fed by underlying mantle that is anomalously hot compared to the surrounding mantle. They can create volcanoes as tectonic plates move over them.

How do hot spots form?

the upwelling of hot mantle material that melts the overlying crust, resulting in volcanic activity. This can occur independently of tectonic plate boundaries.

How are hot spots different from volcanism at plate boundaries?

Volcanism at plate boundaries is typically associated with tectonic activity such as subduction or rifting, while hot spots can produce volcanism in the middle of tectonic plates, independent of their movements.

What is the difference between Volcanic Island Arcs and Volcanic Island Chains?

Volcanic Island Arcs are formed at convergent plate boundaries where an oceanic plate subducts beneath another oceanic plate, leading to a curved chain of islands. Volcanic Island Chains, such as those formed by hot spots, are linear chains of islands created as a tectonic plate moves over a stationary hot spot.

Elastic deformation

A temporary change in shape or size of a material under stress, which returns to its original form when the stress is removed.

Plastic deformation

A permanent change in shape or size of a material when subjected to stress beyond its elastic limit.

Brittle deformation

The fracturing or breaking of a material when subjected to stress, typically occurring in hard materials at low temperatures.

Ductile deformation

The ability of a material to undergo significant plastic deformation before rupture, often seen in metals at high temperatures.

Dip-slip faults

Faults where the movement is primarily vertical, caused by compressional or extensional forces.

Strike-slip faults

Faults where the movement is primarily horizontal, caused by lateral shear forces.

Reverse faults vs thrust faults

Both are types of dip-slip faults; reverse faults have a steeper angle and are formed by compressional forces, while thrust faults have a gentler angle.

What directed stress commonly forms folds?

Compressional stress commonly forms folds in the Earth's crust.

Monoclines

simple bends

basins

depressions

domes

uplifted areas

What are special properties of minerals?

iridescence, magnetism, radioactivity, fluorescence, phosphorescence, effervescence, double refraction, specific gravity

How do minerals break if they do not have cleavage?

they break in an irregular manner, often resulting in jagged or uneven surfaces. This is known as fracture.

Which is the most common rock forming mineral group and why?

silicates because they make up about 90% of the Earth's crust due to the abundance of silicon and oxygen.

What are the six major groups of silicates?

1) Olivine (dark ferromagnesian silicate), 2) Pyroxenes (dark ferromagnesian silicate), 3) Amphiboles (dark ferromagnesian silicate), 4) Micas (sheet silicates), 5) Feldspars (framework silicates), 6) Quartz (framework silicate).

What defines carbonates in mineral groups?

the presence of the carbonate ion (CO3) in their composition.

What defines silicates in mineral groups?

having silicate tetrahedron (SiO4) in their composition.

A halogen bonded with cations like Na, F (ex. flourite)

Halides

Metal ions bonded with sulfur (ex. galena)

Sulfides

Oxygen bonded with metal ions like Fe (ex. hematite)

Oxides

Cations like Ca or Mg bonded with the anion complex CO3 (ex. limestone)

Carbonates

Cations bonded with silica tetrahedra (SiO4) (ex. feldspar)

Silicates

Cations bonded with PO4^3- (ex. apatite)

Phosphates