Plate Boundaries
plates move apart
divergence
what fossils were found in S America and Africa
mesosaurus
who studied "tongue stones" to develop the geologic time scale
Nicholas Steno
how are earthquakes evidence of plate movement
earthquakes occur at plate boundaries, showing where plates are moving
what geologic events occur at the San Andreas Fault (California)?
earthquakes
plates move together
convergence
why couldn't mesosaurus swim across the ocean
it was a small, freshwater reptile; not capable of ocean travel (saltwater)
what is relative dating
determining the age of rocks/fossils based on the layers they are found in; older rock is buried deeper and younger rock is layered on top
how does rifting create features like the Baja Peninsula or the Gulf of California
divergence pulls land apart, magma rises to form new crust that fills in with seawater
why don't transform boundaries form volcanoes
no magma rises to the surface, plates slide past each other
at a convergent boundary, what happens to the plate that sinks beneath the other
sinks into the mantle and is destroyed adding to the mantle
how do shapes of continents support the theory of continental drift?
they fit together like a puzzle
list in order of time (longest to shortest)
eon = largest unit of time
era = middle
period = smallest unit of time
why is the ring of fire so volcanically active
many convergent boundaries surround the Pacific plate
geologic feature found where the Indian Plate collides with the Eurasian Plate
Himalayan mountains
landforms at divergent boundaries that occur onland
rifts
how did wegener use fossils and landforms to support the theory of Pangea?
matching fossils and landforms on different continents
what is the importance of studying rock layers
rock layers record past events, climates and life; helps us to understand Earth's history
if a new mid-ocean ridge forms today, what evidence would be seen on the ocean floor
rising magma, new crust, underwater mountains
if a new volcanic island appears, what evidence supports its formation by divergent plate motion
rising magma and new crust
landforms and geologic activity at three different boundary types
convergent: trenches, mountains, volcanoes
divergent: mid-ocean ridges/rifts, volcanic islands
transform: earthquakes, no volcanoes
what does finding a tropical plant fossil in Antarctica suggest about plate motion?
Antarctica was once in a warmer climate and connected to other continents in a warmer climate
how can relative dating and fossil evidence combine to determine the past sequence of events
analyzing which fossils appear in which layers, allows scientists to reconstruct the sequence of events and evolution over time
what happens if a divergent boundary stops producing crust
how would it affect plate motion
plates would slow down or stop moving, old crust would not be replaced
compare the Baja Peninsula and the Jalisco Block, why do geologists study them together