Geology
Guessing how old a rock is based on the age of other rocks.
Relative Age Dating
When there is a gap in the rock record.
Unconformity
Large sheets of rock that make up the surface of Earth
(Tectonic) Plates
A large landmass that contained all the continents
Supercontinent or Pangaea
The sudden and violent shaking of Earth's crust.
Earthquake
A fossil that helps to date the age of the rock.
Index Fossil
One of the main reasons geological time switches to a new era.
Mass Extinctions
A plate boundary where the plates are moving away from each other
Divergent Boundary
What theory did Alfred Wegener propose for why the continents move.
Continental Drift
Below ground lava is known as ______.
Magma
The principle that in undisturbed rock layers, the oldest rocks are on the bottom
Superposition
The process that helped form the Grand Canyon.
Erosion or Weathering
A plate boundary where the plates are moving towards each other
Convergent Boundary
A crack in the Earth's crust
Fault
Stratovolcano
Principle stating that most rock-forming materials are deposited in horizontal layers.
Original Horizontality
In Geological time, Eras are subdivided into _______.
Periods
A plate boundary where the plates are sliding horizontally across each other
Transform Boundary
Divergent Boundary
The area where a volcano forms in the middle of a plate.
Hot Spot
Principle stating that a fault is younger than the rock it cuts across.
Cross-cutting Relationship
The things that happened in Geological time now are the same that happened in the past.
Uniformitarianism
When a more dense oceanic plate goes underneath a less dense continental plate
Subduction Zone
A mountain created by the folding of Earth crust at a convergent boundary.
Fold Mountains
a scale that measures the intensity of an earthquake based on its effects on people and structures.
Modified Mercalli Scale