Part 2 Science Info
At locations where where sea-floor spreading occurs, what replaces the rock that is moved apart?
Molten rock
Gondwanaland-
One of two pieces that collided to form Pangaea
Laurasia-
One of two pieces that collided to form Pangaea
What is the study of Earth's magnetic record?
Paleomagnetism
The large landmass that existed 250 million years ago is called:
Pangaea
Magnetic reversals in oceanic crust provide proof of:
Sea-floor spreading
What were 4 pieces of evidence that Wegener used to support the theory of continental drift?
1-Mesosaurus fossils matched across oceans 2-Rock types matched on different continents 3-The jigsaw nature of the continents 4-Ice sheet evidence from the paleozoic era matched across continents
Pangea and its breakup
200 million years ago it began to break into two continents (laurasia and Gondwanaland). A large rift split the super continent from east to west. Laurasia drifted northward and rotated slowly and a new rift formed. That separated into North America and Eurasia. Gondwanaland broke apart and became South America and Africa. 150 million yrs ago a rift between South American and Africa opened to for the South Atlantic ocean and other continents.
Who developed the theory of continental drift?
Alfred Wegener
Which scientists contributed to the continental drift theory?
Alfred Wegener Frank Taylor Howard Baker
How does new sea floor form?
As the ocean floor spreads apart at a mid-ocean ridge, magma rises to fill the rift and then cools to form new rock. As this process is repeated over millions of years, new sea floor forms.
What is false about catastrophism?
Catastrophism is not currently accepted by geologists.
Oceanic plate vs Continental plate
Continental plates are thicker and less dense. Continental plates are mainly granitic in composition. Oceanic plates are mainly basaltic in composition. The rock of continental plates is on average, much older than the rock of the oceanic plates. The oceanic plate underlies the oceans, and the continental plate makes up the land masses. Continental plates do not subduct at convergent plate boundaries.
Seafloor spreading happens at:
Divergent boundaries
What important information have we found through paleomagnetism that led to understanding of continental drift.
Due to studying the study of magnetic properties of rock, we can tell that certain rocks on different continents are the same and some of the same fossils were found, which tells us that the continents might have one been together (Pangea).
True or False: Near the mid-Atlantic ridge, the rock is older than the rock near the North American coast.
False
How is seafloor spreading related to continental drift?
Hess suggested that if the ocean floor is moving, the continents might be moving as well.
What was a weakness of Wegener's theory?
Lack of a proven mechanism for moving plates
What is the plate tectonics theory?
The belief that Earth's crust and upper mantle is broken into sections.
What is the continental drift theory?
The belief that continents have moved slowly apart to their current locations on Earth.
Panthalassa-
The ocean that surrounded Pangaea
What is true about the polarity of seafloor crust?
The polarity of the rock on the seafloor is a mirror image on each side of the mid-ocean ridge.
Seafloor spreading
The process by which new oceanic lithosphere forms as magma rises to Earth's surface and solidifies at a mid-ocean ridge
Pangaea-
The supercontinent that formed about 350 mya
Rhodinia-
The supercontinent that predated Pangaea
Catastrophism
The theory that changes in the Earth's crust during geological history have resulted chiefly from sudden violent and unusual events.
Frank Bursley Taylor and Howard Baker
They contributed to the continental drift theory.
Define Uniformitarianism
Uniformitarianism is an important principle for geologists, as it states that processes that happened today have occurred in the past.
What did the theory of continental drift not adequately explain?
Why continents drifted across Earth's surface
As rock moves away from the mid-ocean ridge, it is replaced by:
molten rock
Which type of crust is the most dense?
ocean