the formation of new areas of oceanic crust, which occurs through the upwelling of magma at midocean ridges and its subsequent outward movement on either side.

अब Quizwiz के साथ अपने होमवर्क और परीक्षाओं को एस करें!

What causes the magnetic fields?

Earth's outer core

What is reversed polarity?

It is after a magnetic reversal when a magnet points south

What is transform?

It is where plates slide past each other

What is divergent boundaries?

It is where two plates are moving away from each other and new crust is forming from magma that rises to the Earth's surface between the two plates.

Why does seafloor spreading occur?

It occurs because molten material beneath Earth's crust rises to the surface

What is seafloor spreading?

Seafloor spreading is the formation of new areas of oceanic crust, which occurs through the rising of magma at midocean ridges and its outward movement on either side.

What is the abyssal plain?

When sediment forms on top of the oldest oceanic crust, making smooth seafloor

How do you detect magnet fields on the seafloor?

by using a magnetometer

Where was the Himalayan mountain range of india formed?

convergent boundary

Scientists believe that differences in ____ cause hot, plasticlike rock in the asthenosphere to rise toward Earthh's surface.

density

What are two examples of tectonic activity?

earthquakes and volcanoes

Who is Alfred Wegener?

he is a German Scientist who studied whether Earth's continents move

Where does plates of the lithosphere float?

in the asthenosphere

What is a mid-ocean ridge?

it is large mountain ranges in the middle of the ocean

What is continental drift?

it is the hypothesis that suggests that continents are in constant motion on Earth's surface

What is normal polarity?

it is when a magnetic field causes a magnet to point north

What is magnetic reversal?

it is when a magnetic field reverses

What is convergent-collision?

it is where plates of equal density crash together

What is convergent-subduction boundaries?

it is where the dense plate sinks below the les dense plate

What does the magnetometer show?

it shows parallel magnetic strips on either side of a mid-ocean ridge

Where do plates usually form?

plate boundaries

What is ridge push?

plates are pushed away from each other at mid-ocean ridges

The presence of the same _________ on several continents supports the hypothesis of continental drift.

rocks and fossils

Continental drift states that continents have moved ______ to thier current location

slowly

Where is the youngest part of the ocean floor found?

near ocean ridges

What causes earthquakes?

when 2 plates that have equal density collide, slide past each other, or seperate in a plate boundary

What is slab pull?

when a plate sinks below another plate, it pulls on the rest of the plate

What form mountains?

when continental plates collide together

What causes volcanoes?

when dense plates sink below less dense plates

What is convection currents?

when materials move based on differences in thier temperatures and desnites. Heat rises and cold sinks

What is Pangaea?

when wegener proposed that all continents were once part of a single supercontinent

Scientists have observed that the continetns move apart or come together at speeds of a few centimeters per _______

year

How did scientists map the depth of the ocean floor?

They did it by using a device called an echo-sounder

What do these parallel magnetic strips show?

They show alternate normal polarity and reversed polarity, showing that each stripe was formed at the mid-ocean ridge and then moved away

What evidence did scientists use to support thier hypothesis?

They use similar fossils, plants and climate

The existence of coal beds in Antarctica indicated that the continents once had _______

a tropical, rainy climate

The crust and upper mantle makes up Earth's _______

lithosphere


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