Unit 2: Geological Oceanography

gravity

an attractive force between any two objects of mass

Density

Mass per unit volume

Rotation

The spinning on a internal axis

Revolution

The movement of an object around an external point

Barycenter

the point which two bodies of mass revolve around

geological time

a relative time scale based upon major geologic and evolutionary events which are recorded in the rock layers of earth

Isostasy

the state of gravitational equilibrium in which an are of crust "floats" in a balanced way on the denser underlying mantle.

convection current

the circular flow of material caused by hot less dense magma rising while more dense magma cools and sinks

divergent boundary

tectonic plates move apart from each other

convergent boundary

tectonic plates move towards eachother

tranform fault (transform boundary)

when two tectonic plates slide past each other

ridge push

the upwards and outward force on a plate- caused by hot less dense magma rising

slab suction

the downward pull on the end of a plate- caused by cool more dense magma sinking

slab pull

the horizontal force on the bottom of a plate that helps to drag the plate along

continental shelf

the submerged seaward edge of the continent

continental edge (shelf break)

the transition area between the continental shelf and the continental slope

continental slope

the "steep" edge of the continent as it transitions down to the deep ocean floor.

continental rise

transition area between the continental slop and the abyssal plain

abyssal plain

the flat featureless deep sea floor

mid-ocean ridge

a mountain range in the middle of the ocean at a divergent plate boundary formed by ridge push

ocean trench (deep sea trench)

a depression in the sea floor at a convergence boundary where an oceanic plate Is being subducted

hydrothermal vents

a fissure or crack in the ocean floor from which super heated mineral pouch water is expelled.

continental margin

area where the continent meets the seafloor or the area where the continental crust meets the oceanic crust.

active margin

the area where the continent meets the seafloor at a plate boundary

passive margin

the area where the continent meets the seafloor and there is no plate boundary

sediment

particles that have settled to the bottom of a liquid

sedimentation

the process of particles building up at the bottom of a liquid

weathering

the breakdown of rock

Erosion

the movement of sediment away from an area

Deposition

the buildup of sediment in an area

chemical weathering

the deterioration of rock by chemical interaction ex: oxidation, acid rain, dissolved by water

physical weathering

the breakdown of rock without altering its chemical composition ex: scrubbing by sediment carried by water

organic weathering

the breakdown of rock by biological organisms

lithogenous sediment

sediment that comes from pre-existing rock

biogenous sediment

sediment that is composed of material built by organisms

ooze

sediment that is made up of >30% of biogenous sediment

hydrogenous sediment

mineral material that precipitates out of the sea water

calcareous ooze

made up of calcium carbonate

siliceous ooze

biogenous sediment composed of silica

neritic sediment

sediment found on the continental shelf

pelagic sediment

sediment found covering the deep ocean floor

Littoral Zone (aka Intertidal Zone)

the transition area between the land the sea

three littoral zones

muddy short, sandy shore, rocky shore

Estuary

sheltered area where fresh and saltwater mix

the relationship between mass and gravitational force

as the mass of an object increases, the gravitational force between them increases,

State the distance between objects and the gravitational force

the increase in distance between two objects, the less gravitational force is exerted

uppermost layer of the mantle

asthenosphere

upper portion of the asthenosphere and the lower portion of the crust

lithosphere

Angle at which the Earth is tilted

23.5 degrees

Theory of Continental Drift

the idea that al continents were once a single supercontinent which broke up and have drifted around the planet to their current. positions (Pangea)

Theory of Plate Tectonics

the earth's crust is broken up into lithospheric plates. These plates float on the underlying mantle and are pushed around by convection currents in the mantle

the major type of rock that makes up the oceanic crust

basalt

the major type of rock that makes up the continental crust

granite

why lithospheric plates float on the asthenosphere

lithospheric plates are less dense than the asthenosphere

term used to describe the amount of suspended particles in water

turbidity

4 time periods geological time is divided into from longest to shortest

eon, era, period, epoch

how earths different layers formed

As the planet cooled, dense elements became concentrated in the core of the planet, while lighter elements formed the mantle.

what earths core is like

there is an inner solid core which is spinning while the outer liquid core is like flowing currents

how the moon is formed

the giant impact theory - about 100 million years ago after the earth formed, while it was still mother rock a small planetoid struck earth ejecting debris out into space, debris came together and formed the moon in earth gravitational field

difference between absolute and relative time scales

absolute time scales are the measure of time that give numerical value while relative time scales compares when an event took place to when others take place

the difference between the S and P waves

S waves are slower while P waves are first to arrive, they both oscillate

difference between a muddy shore, sandy short and a rocky shore

Muddy- very shallow. little water movement, least exposed
Sandy - shallow to gradually sloping shore line, loose deposits for sand, sediments are in constant motion
Rocky - more biodiversity , slope varies widely, vary in size from pebbles, high erosional forces with little sedimentation

different between weathering and erosion

Erosion is the process in which rock particles are carried away by wind, water, ice, and gravity. In Contrast, Weathering, is the breakdown of rock

what causes earth magnetic field

The spinning of the inner core
causes currents in the outer
core which give earth its
magnetic field.

difference between a passive and an active margin

the active margin is the area where the continent meets the seafloor at a plate boundary and the passive margin is the area where the continent meets the seafloor and there is no plate boundary

the difference between neritic and pelagic sediment

Neritic sediments are found in shallow coastal areas, have a coarser texture, and contain more terrigenous material, while pelagic sediments are found in deeper open ocean regions, have a finer texture, and contain a significant amount of biogenic material from marine organisms.

what caused earths equatorial diameter to be slightly larger than its polar diameter

Earth's equatorial diameter is slightly larger than its polar diameter due to the centrifugal force resulting from the planet's rotation, which causes material to move away from the axis of rotation, leading to an equatorial bulge and a flattening at the poles. This oblate spheroid shape is a consequence of the Earth's rotational dynamics and non-uniform mass distribution.

why do lithospheric plates float on the asthenosphere

lithospheric plates float on the asthenosphere because they are less dense than the underlying mantle and because the semi-fluid asthenosphere allows for plastic deformation and slow flow. The movement of the plates is driven by the convection currents in the mantle, where hot material rises and cooler material sinks, creating a dynamic system that shapes the Earth's surface through plate tectonics.

what causes volcanoes to form along coastlines that are near oceanic trenches

Volcanoes form near oceanic trenches when an oceanic tectonic plate is forced beneath another plate at a subduction zone, leading to the melting of rock in the Earth's mantle and the creation of magma that rises to the surface, resulting in volcanic eruptions

How are mid-ocean ridges formed?

Mid-ocean ridges are formed by the upwelling of hot mantle rock at divergent plate boundaries, creating new oceanic crust as tectonic plates pull apart.

what causes paleomagnetic banding on the seafloor

Paleomagnetic banding on the seafloor results from the recording of Earth's changing magnetic field by magnetic minerals in oceanic crust as it solidifies and spreads at mid-ocean ridges during geomagnetic polarity reversals.

what causes the sediment size to differ between a rocky, sandy, and muddy short

the differences in sediment size between rocky, sandy, and muddy shores are primarily driven by the geological characteristics of the shorelines, the energy of the environment, and the processes of erosion, transport, and deposition that occur in each setting. Rocky shores have small sediments due to rock weathering, sandy shores have sand-sized particles due to wave action, and muddy shores have fine sediments due to low-energy conditions and organic matter accumulation.

diagram of the ocean basin

How oceanic trenches are formed

Oceanic trenches are formed through subduction zones where one tectonic plate is faced beneath another which creates a convergent boundary.

Crust

• The solid, outermost layer of earth

  • Oceanic Crust - Thinner  (5 to 10 Km)

  • Continental Crust - Thicker (30 to 70 Km

Mantle

• Is a layer of semisolid rock between the core and crust.

• It is plastic in nature

• Moves slowly over geologic timescales

• The upper portion known as the asthenosphere is highly viscous

Core

• The densest, innermost layer of the earth.

• Composed of mostly nickel and iron

• Inner solid core

• Outer Liquid core

Neritic zone

shallow part of the ocean located between the intertidal zone and the oceanic zone. Over continental shelf

shelf break

•  the transition area between the continental shelf and the continental slope.

subduction zone

Area where subduction takes place. 

List and Describe two types of crust.

Continental: 30-70km thick

• Made up of mostly granite (slightly less dense rock)

Oceanic: 5-10km thick

• Made up of mostly Basalt (very dense type rock)

List three pieces of evidence that support Wegener’s Theory of Continental Drift.

• The coastlines of continents appeared to fit together like puzzle pieces.

• Similar plant and animal fossils were found on different continents in areas that appear to line up if all the continents were together

• Similar type of rock and rock formations on different continents in areas that would appear to line up it the continents were together.

List two reasons why Wegener’s Theory of Continental Drift was initially rejected.

• Couldnt explain the mechanism for why continents were moving apart

• Could not explain where they were moving from

List and describe two pieces of evidence that supported seafloor spreading.

• The further the rock sample from the mid-ocean ridge the older the rock samples became.

• Alternating bands of magnetic polarity on either side of the mid-ocean ridge. The pattern of banding was the same on both sides of the ridge.

List five pieces of evidence that supports the Theory of Plate Tectonics.

• All of Wegener’s evidence

• All of the evidence for Seafloor Spreading

List three types of plate boundaries.

• Divergent Boundary

• Convergent Boundary

• Transform fault (transform boundary)

List the three types of tectonic forces.

• Ridge Push

• Slab Suction

• Slab pull

List two types of continental margins.

• Active

• Passive

List three ways in which sediment could be categorized.

Location

Size

Origin

List three origins of marine sediments.

Lithogenous Sediment

Biogenous sediment

Hydrogenous Sediment

List two ways to categorize marine sediment by location.

Neritic

Pelagic

List and describe three types of shores.

Muddy, sandy, rocky

Describe the process by which new seafloor is made. 

Seafloor spreading occurs at mid-ocean ridges, where tectonic plates diverge. Magma rises from the mantle to fill the gap between the separating plates, solidifying as it cools and forming new oceanic crust. This process continuously adds to the seafloor, pushing older crust away from the ridges, and plays a crucial role in the movement and recycling of Earth's tectonic plates.

Describe how volcanoes form along coastlines that are near oceanic trenches. 

Volcanoes near oceanic trenches form due to the process of subduction, where one tectonic plate is forced beneath another at a convergent boundary. As the denser oceanic plate subducts beneath the less dense continental or another oceanic plate, it sinks into the Earth's mantle. The descending plate is subjected to immense pressure and heat, causing it to partially melt, forming magma. This magma, being less dense than the surrounding rock, rises through cracks and weaknesses in the overriding plate. When the magma reaches the Earth's surface, it can erupt, forming volcanoes along the coastline near the oceanic trench

Describe how paleomagnetic banding of the seafloor is evidence for seafloor spreading.  

• Alternating bands of magnetic polarity on either side of the mid-ocean ridge.

• The pattern of banding was the same on both sides of the ridge.

  • Bands were the same width and the same distance from the ridge.

Describe how oceanic trenches form. 

Oceanic trenches typically occur where oceanic plates collide with continental plates or another oceanic plate. When two plates converge, one plate is forced beneath the other in a process called subduction. The process of subduction begins when the denser oceanic plate is subjected to the intense pressure and heat as it descends into the Earth's mantle beneath the less dense continental or another oceanic plate.

Describe what the age of the rocks samples taken from the seafloor tell us about how the ocean formed. 

The further from the mid-ocean ridge the older the rock samples became.

Describe the difference between a passive and an active margin. 

Passive: area where the continent meets the seafloor and there is no plate boundary - continental and oceanic crust are fused together and there is no movement.

Active: - area where the continent meets the seafloor at a plate boundary - there is movement