Ch. 11 NotesDeformation of the Crust
How Rock Deforms
Earth’s surface changes constantly Isostasy
When lithosphere and asthenosphere are balanced
If weight of lithosphere changes, it sinks or rises until there is a balance again
How Rock Deforms
Stress Force exerted on a rock
as lithosphere moves Types of stress:
Compression – squeezes and shortens
Tension – stretches and pulls
Shear stress – parts pushed in opposite directions
How Rock Deforms
Strain When rock changes its shape or volume
because of stress Stress doesn’t always change a rock, it can
“bounce back”
How Rock Deforms
Folds Bend in rock layers
that results from stress
Result of compression or shear stress
How Rock Deforms
Faults Break in rock where surrounding rock moves Earthquakes occur along fault lines
Mountain Ranges
Mountain ranges believed to be formed by once active tectonic plates Results of collisions between:
Continental and oceanic crust Oceanic crust and oceanic crust Continental crust and continental crust
