Marine Science Unit 1

Where would you find the oldest rock on the sea floor?

In a deep sea trench

How does the Earth’s periodic magnetic field reversal provide evidence of sea floor spreading?

As oceanic crust is formed, particles align themselves to the current magnetic field

What type of structure do you find at a Shear Boundary?

Fault

The two kinds of crusts are 

oceanic crust and continental crust

Series of underwater mountain chains are called

mid-oceanic ridges

Iceland is part of the 

mid-pacific ridge

Oceanic crust near a mid-ocean ridge is ____ than crust far away.

younger

The deep crack running down the center of an ocean ridge is called a 

rift valley

New ______ crust is formed at the mid-ocean ridges

oceanic

Seafloor spreading is a process that forms new _____ crust

oceanic

Asthenosphere

the rest of the upper mantle that includes slow swirling rock that drives the movement of the lithospheric plates

Density

The amount of mass in a given volume of a substance (mass/volume).

Hydrothermal Vents

deep springs; openings on the seafloor where superheated, mineral-rich water is released from beneath the Earth’s crust.

Lithosphere

The rigid outer layer of the Earth, made up of the crust and the uppermost part of the mantle.

Mariana Trench

The deepest part of the world’s oceans

Mid-Ocean Ridge

An underwater mountain range formed by tectonic plates moving apart (diverging) along the ocean floor.

Plate Tectonics

the movement of large plates of Earth’s crust

What do plate tectonics explain?

how the lithosphere is broken up into tectonic plates

Seamounts

underwater volcanoes or mountains that rise from the seafloor but do not reach the ocean’s surface.

Sediment

Loose particles of rock, minerals, or organic material that settle at the bottom of bodies of water like oceans, rivers, and lakes.

Weathering

The process that breaks down rocks and minerals on Earth’s surface into smaller pieces by physical, chemical, or biological means.

Active vs. passive margins

Active margins are found along plate boundaries with high tectonic activity while passive margins are along coasts not near plate boundaries.

Divergent boundaries

plates move apart, which causes tension stress (mid-atlantic ridge)

Convergent boundaries

plates move together, which causes tension stress (mariana trench)

Transform boundaries

plates slide past each other, which causes shear stress (San Andreas Fault)

Who was Alfred Wegner?

A German scientist who proposed the continental drift theory

Layers of the Earth

crust, mantle, outer core, inner core

crust

thin, solid outermost layer

mantle

thick layer of semi-solid rock

outer core

liquid iron and nickle

inner core

solid iron and nickle

examples of subduction zones

Mariana Trench (Pacific Plate under Philippine Plate), Andes Mountains (Nazca plate under South American plate), Japan Trench (Pacific Plate under Eurasian plate)

Compare oceanic and continental crust

• Oceanic: Basalt (dark, dense rock), thin, more dense, younger

• Continental: Granite (light, less dense rock), thick, less dense, older

evidence for continental drift and plate tectonics

fit of continents, fossils, rock formations, mountain ranges

2 types of marine sediments

terrigenous, biogenous

terrigenous sediment

from land (erosion of rocks, carried by rivers and wind)

biogenous sediments

from the remains of marine organisms (shells, skeletons)

Where is the sea-floor made?

mid-oceanic ridges

Where would a “recycling” zone be found?

subduction zones

What are the major basins of the world ocean?

Pacific, Atlantic, Indian, Arctic, Southern

Why is the oceanic crust so much younger than continental crust?

oceanic crust is continuously formed at mid-oceanic ridges and recycled back into the mantle at subduction zones, while continental is not.