Plates on the Move
The giant, rigid pieces that Earth's lithosphere is broken into.
What are tectonic plates?
The ocean that the Ring of Fire circles.
What is the Pacific Ocean?
The supercontinent whose name means "all land."
What is Pangea?
Any preserved evidence of past life.
What is a fossil?
In a stack of rock layers, the oldest layer is usually found here.
What is the bottom?
Most plates move about 2–15 cm per year, about the same speed as this part of your body grows.
What are fingernails?
The two kinds of events that happen most often along the Ring of Fire.
What are earthquakes and volcanoes?
The German scientist who proposed continental drift in 1912.
Who is Alfred Wegener?
Footprints, burrows, and fossilized droppings are examples of this kind of fossil.
What is a trace fossil?
All known fossils, arranged in order by age.
What is the fossil record?
The type of plate boundary where two plates move apart.
What is a divergent boundary?
The process where a denser plate is pushed down beneath another plate into the mantle.
What is subduction?
The two continents whose coastlines first gave Wegener the idea that continents fit together like puzzle pieces.
What are South America and Africa?
Hardened tree resin that can trap and perfectly preserve insects.
What is amber?
This natural process carved the canyons of Utah and exposed layers full of fossils.
What is weathering and erosion?
The process that forms new ocean crust when plates pull apart and magma rises to fill the gap.
What is seafloor spreading?
This mountain range is still growing because the plate carrying India keeps pushing into the plate carrying Asia.
What are the Himalayas?
A freshwater reptile whose fossils are found in both South America and Africa, even though it could not swim across an ocean.
What is Mesosaurus?
A hollow, organism-shaped space left in rock after the remains dissolve away.
What is a mold?
A fossil that shows features partway between two different groups of organisms.
What is a transitional fossil?
California's San Andreas Fault, where two plates slide sideways past each other, is this type of boundary.
What is a transform boundary?
The reason two colliding continental plates crumple into mountains instead of one sinking and making volcanoes.
What is: both plates are too light (not dense enough) to sink into the mantle?
The thing Wegener was missing that made scientists reject his idea for decades.
What is a mechanism (an explanation of how continents could move)?
The process that forms most dinosaur bones, where minerals from groundwater slowly replace the bone.
What is permineralization?
A transitional fossil with fins and gills like a fish, but leg bones and lungs like a land animal.
What is Tiktaalik?