dynamic earth Flashcards
What is the lithosphere?
The ;ayer of rock that forms the outer shell of earth
Define the Crust-
the uper part of the lithosphere (crust and litosphere mean same thing)
What is evidence for past movement of crust based on?
It’s based on the concept of original horizontal
What is the original horizontally concept
The concept assumes that sedimentersry rock layers form horizontal layers or strata
Most strata that are found in positions other than Horizontal are deformed be what?
Crystal movement
List the deformed layers
Folded
Faulted
Tilted
Describe folded layers-
Layers are bent or curved
Describe faulted layer
Layers are offset along a crack called the fault
Describe tilted layer
Layers are slanted or tipped
What is uplift
When the earths crust is raised up
What is uplift usually indicated by?
Ocean rocks or marine fossils found at very high elevations
What is sinking
The lowering of earths crust
How does one recognize sinking
From when sedimenterary rocks or marine fossils are found hundreds of meters below sea level
Define earthquake
A natural rapid shaking of the lithosphere when stored energy in rocks is released
What are most earthquakes caused by?
Movement along faults
What is potential energy stored in rocks given off as in an earthquake
Seismic waves
Where do seismic waves originate and radiate
they originate at the focus and radiate in all directions
What is a seismograp
an instrument used to measure earthquake waves,
how do seismographs record earthquakes.
they record earthquakes by the earth shaking a paper.
define a P wave
primary waves which travel in the same direction as they vibrate
Define S waves
Secondary waves which vibrate at right angles to the direction they travel.
Define a surface waves
When P or S waves reach the Earth’s surface. These waves cause the most shaking and damage
What are the earthquake waves
P waves
S Waves
Surface Waves
Why do P waves reach the seismograph first?
because the P waves travel the fastest
