Chapter 11 & 12 Flashcards
What is continental drift?
the idea that the continents move around the Earth.
Who discovered the continental drift
Alfred Wegener
What was Wegener’s hypothesis?
He hypothesized that the continents were once connected.
Was Wegener right?
YESSSSS
What is Pangea?
(Greek for “all land”). An ancient, huge landmass composed of earlier forms of todays continents; an ancient super continent.
What is a supercontinent?
Its the very large landmass that separated to make the continents.
What is Wegeners evidence for continental drift?
- Coal bed match each other in eastern U.S and southern Europe.
- Plant fossils found in South America, Africa, India, Australia, and Antarctica.
- Matching reptile and mammal fossils found in South America and Africa.
- Evidence of glaciers in warm, dry areas that show that they used to be closer to the South Pole.
Was Wegener’s hypothesis good?
YESSSSSSSSSS and was based on observations.
Why did scientists initially reject the continental drift?
There was no evidence to explain HOW the continents moved.
What is a mid-ocean ridge
a long chain of undersea mountains.
Why was the ocean floor mapped for the first time?
It was for the United States Navy to locate enemy submarines hiding on the bottom of shallow areas.
Who is Harry Hess?
He is an American geophysicist and naval officer who did a lot of the ocean mapping of the ocean floor.
What was Hess’s idea?
A new ocean floor is created at deep mid-ocean ridges. This pushes apart the continents that meet at that mid-ocean ridges.
What is sea-floor spreading?
a hypothesis that new sea floor is created at mid-ocean ridges and that, in the process, the continents are pushed apart from each other.
What was one key piece of evidence for Hess’s hypothesis?
Magnetic Reversal Patterns
What is magnetic reversal patterns?
They are patterns formed in new rock formations by the Earth’s magnetic field. The patterns harden as the rock cools.
What did scientists notice about magnetic reversal patterns?
They noticed that the magnetic patterns matched on either side of the ridge. The oldest rocks were furthest from the ridge.
What are lithospheric plates?
large pieces of Earth’s lithosphere that move over the asthenosphere.
What are two types of lithospheric plates?
The oceanic and continental plates.
What are oceanic plates made of and formed?
It is made of basalt and formed the ocean floor.
What are continental plates made of and how are they different from oceanic plates?
It is made of andesite and granite and is less dense than the oceanic plate.
What drives the lithospheric plates on the surface?
Convection Cells in the lower mantle of the Earth.
What happens in the mid-ocean ridge when lithospheric plates move?
Convection cell in the mantle moves the lithospheic plate.
Basaltic lava goes through the mid-ocean ridge and joins the lithospheric plate where it makes it bigger.
What is subduction?
a process that involves a lithospheric plate sinking into the mantle.
Describe the parts of the convection cell moving the lithospheric plates?
Page 252. - Hot lower mantle rises up
- The lava comes up through the mid-ocean ridge and adds on to the plate and cools.
- The mantle material is moving and carrying the lithospheric plate like a passenger
- SUBDUCTION, the mantle material cools and the plate starts to sink.
What is mantle plume?
heated lower mantle rock that rises toward the lithosphere because it is less dense than surrounding mantle rock.
How can a mantle plume cause and island?
When there is a big volcanic eruption it can form and island.
What are three type of boundaries between lithospheric plates?
Divergent convergent, and transform fault boundary
What is a divergent boundary?
a lithospheric plate boundary where two plates move apart.
What is a convergent boundary?
a lithospheric plate where two plates move into each other.
What is a transform fault boundary?
A lithospheric boundary where two plates slide by each other.
