Evidence for Plate Tectonics Flashcards
What is a fundamental theory of geology that unifies a lot of processes that we observe on our planet?
the theory of plate tectonics
the first step in the scientific method is…
to develop a hypothesis
if a hypothesis passes a(ny) number of tests then it develops into a …
theory
what did Alfred Wegener propose?
that in the more recent geologic past, (200 million years ago) there was a super continent known as Pangea where all the continents were joined together
how many years ago is the more recent geologic past?
200 - 300 million
what was the problem with Alfred Wegener’s hypothesis?
it didn’t have a mechanism to explain how continents could move across the earth
What was evidence used in Wegener’s Pangea hypothesis?
- he looked at a map and said Africa and South America fit together like puzzle pieces.
- in the boundaries between South America and Africa there were rocks of similar ages
- in North America, Europe and Africa there are mountain chains of similar ages
- looked at glacial landforms such as glacial striations and tracked the movement of glaciers
- evidence of a single species of tree spread across a number of different continents
the fact that Africa and South America fit together like puzzle pieces means that the continental _____ fit
margins
why was Wegener’s hypothesis broadly rejected in the scientific community?
- he could not explain how these continents spread across the globe, just what
Was Wegener a meteorologist or a geologist?
meteorologist
- this contributed to his hypothesis rejection
- its hard to listen to ideas outside of your field because you just don’t afford them the same level of expertise
in the boundaries between South America and Africa there were ____ of similar ages
rocks
there was evidence of a single species of _____ spread across a number of different continents
tree
in North America, Europe and Africa there are _____ chains of similar ages
mountains
if you look at continents individually, if South America were by itself it would appear that glaciers were moving from the coast _____, which doesn’t happen, so Wegener concluded that the continent of South America must have been an ____ portion of a greater continent.
inland, inner
What was the name of the precursor to the theory of plate tectonics?
continental drift hypothesis
