Evidences of Plate Movement

meaning of Pangea

greek for all lands or all earth

pangea is

a supercontinent that dates back 250 million years ago

A plate might include

a continent, parts of a continent, and seafloor

theory in science is

a statement backed by evidences of several tests

hypothesis in science is

statements made without any evidence before an experiment

the ocean that surrounds pangea

the panthalassa

Pangea was mostly in which hemisphere

the southern hemisphere

as of current, which hemisphere are the continents mostly located in

the northern hemisphere

what are the 7 continents of the world

asia, south america, north america, europe, africa, australia, antarctica

who is Alfred Lothar Wegener

he is a german climatologist and arctic explorer who hypothesized in the 1900s that the continents were once connected and that it moves on the earth’s surface

what is the title of alfred lothar wegener’s book

Origins of the Continents and Oceans, published 1915

permian period

last period of the paleozoic era, period of mass extinction before dinosaur extinction, & continents were still pangea (225 million yrs ago)

triassic period

the continents started to drift apart into two, laurasia and gondwana. (200 million years ago)

jurassic period

emerging of new life and dinosaurs. laurasia started to drift northwards and rotate causing a new rift that separated the continents into eurasia and north america, it also formed the north atlantic ocean. gondwana also broke into land continents. (135 million years ago)

cretaceous period

100 million years ago a rift between africa and south america formed the south atlantic ocean. india, australia, and antarctica also began to separate. india broke away from australia & antarctica and moved towards eurasia.

present day period

india collided with eurasia and formed the himalaya mountains. slowly the continents moved into their actual positions. the collisions turn new crust into continents and uplift the land (mountain ranges).

geological fit evidence

continental jigsaw puzzle, matching of geological features on different continents

fossils are

preserved remains of plants and animals

fossil evidences

fossils of the same species are found on continents on different sides of the atlantic ocean. eg. matching reptile fossils in south america and africa

glossopteris was a plant fossil found in which 5 countries.

australia, antarctica, india, south africa, and south america

rock evidences

matching rock features on different continents, eg. appalachian mountains and scottish highlands + glaciers, which carve rocks as they move = determines the direction of continent movement

glaciers were found in

warm continents that weren’t plausible to attain such features

climate evidences

coal deposits were found in antarctica, which should be impossible considering it’s current location. the same were found in south america, africa, and southeast asia

what does the sonar do?

it bounces soundwaves off the seafloor to determine depth and features.

who proposed the seafloor spreading theory

Harry Hammond Hess

what is seafloor spreading

a process where tectonic plates split apart from eachother

seafloor spreading theory states

that magma from below the earth’s crust rises to the surface at the mid ocean ridge, pushes the seafloor away, and then the magma cools and becomes the new seafloor. it also creates new bodies of water

how is the age of the seafloor determined

closest to the ridge is youngest, while further is the oldest

the east pacific rise is

the most active site of seafloor spreading. it is beside north america and south america. spreads 14cm of seafloor every year

rates of seafloor formation and subduction

sometimes creation is faster than subduction, or interchangeably and vice versa

subduction zone is in

ocean trenches, and it is formed by one tectonic plate going under another. (oceanic + continental plate)

what gets destroyed in the subduction zone

old seafloor that is farthest from the ridge.

types of sediments found on seafloor

thinner sediments near the ridge, or younger crust. & thicker sediments on older crust

magnetic reversal

is when the north and south magnetic poles switch

the magnetic field

is created by the movement of the iron and nickel in the outer core, when the flow becomes unstable the places of north and south flips

the magnetic field’s direction is determined by

the crystalized irons in rocks found in the seafloor

hotspot volcanoes are created on

oceanic plates because they are thinner

hotspot

A hot spot is where most volcanoes are created from melting hot rocks in the mantle that build up to the ocean's surface and form an island.

deep-focus earthquakes mostly occur

near ocean trenches, where one plate sinks under another

shallow earthquakes

happen near the surface as a plate starts sinking

deep-focus earthquakes

happen deeper in the Earth as the plate moves farther down