Earth science 9 Flashcards
who proposed the idea of continental drift
alfred wegener
what was pangaea
it means all lands and it was a huge mass of land that had all the continents on it
what book in 1915 did wegner publish for evidence of drift
The origin of continents and oceans
Explain matching fossils
Some fossils like mesosaurus fossils were found in eastern south america and soutern africa. But they are far away so no way a dinosaur could swim that far. so wegener said the continents must have been joined
what were wegeners evidences for continental drift (what animals)
matching fossils(mesosaurus and glossopteris) rock types, and ancient climate.
Explain rock types
when you look at a map you notice that the continents could fit like a puzzle. Then you also notice that the ike mountain ranges in south america and africa lined up almost like they were onced joined
Explain ancient climates
for example, Greenland had warm weathered fossils on it so it was believed that Greenland drifted from the bottom to the top to a colder climate. Wegener also found glacal clues of glacial deposits in southern areas of south America Africa India and australia.
why was wegeners theory laughed at and people did not believe him
because he had no proof. He couldnt explain how when or why these changes happened. Also other scientist couldnt explain it either.
Can we beleive in pangaea and things as christians?
Yes with some modifications and not 200 million years ago.
When was wegeners idea finally accepted
after his death in 1930 scientist began to study his theory and a new theory called plate tectonics was formed.
what gave the best evidence for wegeners hypothesis
sea floor spreading
What helped people in the 1940 and 1950 explore the ocean floor
sonar. It was used to make maps of the ocean floor. and it discoverd underwater mountains and valleys
what are deep ocean trenches
long steep valleys that form in deep parts of oceans. most trenches occure near the edges of the pacific ocean
what is mid ocean ridges
a long chain of mountains extending throughout all oceans. They form the longest feature on earth’s surface.
what are rift valleys
a deep central valley that runs down the center of a ridge called a rift valley. kind of like a canyon
what is the composition of the ocean floor
mostly basaltic or igneous rocks. most of the floor is covered by sediment, thickest near continent and none at ridges.
what is sea floor spreading
a theory made by harry Hess in the 1960s. oldcrust moves out and new crust comes in then the old crust goes down toward mantle.
explain sea floor spreading
As tectonic plates slowly move away from each other, heat from the mantle’s convection currents makes the crust less dense. The less-dense material rises, often forming a mountain or elevated area of the seafloor.
what submarine did ppl use to discover pillow lava?
Alvin. A submerine that could withstand lots of pressure.
How did the life forms that were newly discovered by alvin get their energy if their was no sunlight
Instead of using photosynthesis. They used chemosynthesis. They used chemicals from the vents where the mama reaches the surface.
Explain the movement of the ocean floor
When new floor is added along the ridges the older floor moves outward and away.
How far does the sea floor spread every year
about cm a year
What is subduction
When cooler denser plate sinks down into the mantle.
how do sea floor spreading and subduction work together
Seafloor spreading creates new crust. Subduction destroys old crust.
who invented sea floor spreading
harry hess
what is a mid ocean ridge
an undersea mountain chain where new ocean floor is produced at a divergent plate boundary.
what are the three evidences for sea floor spreading
magnetic stripes, earthquake patterns ,and age of the ocean floor.
what was the Glomar challenger?
A research ship that was used to gather info of seafloor rocks. It had drills that allowed scientist to obtain rock samples.
Explain plates and lithosphere.
plates are separate sections in the lithosphere, they all fit together in the lithosphere.
Who made the scientfiic theory of plate tectonics by joining continental drift and sea floor spreading
J wilson.
what is the theory of plate tectonics explain
it says earths crust and upper mantle are broken into sections called lithospheric plates. plates are in slow motion all the time.
What moves the tectonic plates. Explain
convection currents in the mantle. Hot materials in the mantle move up.
Why do volcanoes mountains forming and earthquakes mostly happen
when plate collide poull apart or grind past each other.
what are the three types of plate boundaries
Divergent boundaries, convergent boundaries and transform fault boundaries.
what is divergent boundaries
when two plates move apart from one another also called spreading centers. most occur along the mid ocean ridges where seafloor spreading occurs..
what is convergent boundaries.
when two plates come together or collide. for every divergent boundary making crust, there must be a convergent making it dissapear.
what is oceanic continental boundary
when continental and oceanic plates converge together. Ocean is denser than land so the ocean sinks under the continental plate.
what is oceanic oceanic boundary
when two oceanic plates collide. the more dense plate slides under the lesser one and forms a subduction zone.
what is continental continental boundary
when two continental plates colliide. These plates are less dense than the material in the asthenosphereso no subduction happens.
what is slab pull
when gravity pulls dense oceanic lithospher down into the deep mantle at evolutionary zone
what is ridge push
ridge push occurs at mid ocean ridges where asthenosphere rises from the mantle causing lithosphere to rise.
heat
transfer of energy from a warmer object to a colder object
what are the three ways heat is transferred.
radiation, conduction, and convection
what is radiation
the transfer of energy by electromagnetic waves this is how heat form the sun comes to the earth
what is conduction
the transfer of energy when moleculs bump into one another. the hotter it is the faster the molecules move.
what is convection
the transfer of hear that occurs because of density difference between air and liquid.
what are convection curretns
the circular motion of a gas or liquid.
When you heat water in the center of a pot the central molecules move more. they spread out incease volume and decrease density so it moves upward.the surface starts to cool so molecules move less. less volume more density water sinks.
what is a continental volcanic ark
a range of continental mountains.
how did the andes mt range form
the convergence of nazca and south america continental plates.
