faults and folds
DESCRIPTION
Faults and Folds. Bends and Breaks. First, rocks are laid down and organized in units. Sedimentary rocks are laid down in layers like a cake by wind and water. This process is called DEPOSTION Igneous rocks are spread over large areas like maple syrup by VOLCANIC ACTIVITY. - PowerPoint PPT PresentationTRANSCRIPT
Faults and FoldsBends and Breaks
First, rocks are laid down and organized in
units. Sedimentary rocks are laid down in layers like a cake
by wind and water. This process is called DEPOSTION Igneous rocks are spread over large areas like maple
syrup by VOLCANIC ACTIVITY. Metamorphic rocks gradually change from one place
to the next by extreme geologic events Rock units and large areas that consist of one kind of
rock created by geologic events that happened millions of years ago.
You can walk for miles and miles and just see one kind of rock.
Faults and Folds are what
BEND and BREAK up rock units.Fault Fold
FRACTURE and FLOW
Fracture Fracture happens when
rocks are at the EARTH’S SURFACE and they are COOL.
Fracture is what happens when rocks BREAK!
Fracture = Faults
Flow Flow happens when
rocks are deep UNDERGROUND and they are very HOT.
Fracture is what happens when rocks BEND!
Flow = Folds
Forces in the Earth Faults and folds happen when masses of rock are
colliding, being pulled apart, or sliding next to each other.
Faults and folds happen when there are COMPRESION, TENSION or SHEAR forces. COMPRESSION happens when two plates collide (Are
pressed together)
TENSION happens when two plates SEPARATE (are pulled apart)
SHEAR happens when two plates slide past each other
Let’s see this in action
http://scign.jpl.nasa.gov/learn/plate5.htm
FAULTSFaults are the result of FRACTURE. They
are the result of forces in the earth that BREAK rocks. Fracture happens when rocks are cool.
There are 3 major types of faults: Normal = Compression Reverse = Tension Slip-strike = Sheer
Normal Fault
Normal faults occur when two plates PULL AWAY from one each other.
They are caused by TENSION forces
Reverse Fault
Reverse faults occur when two plates are PUSHED together
Reverse Faults are caused by TENSION forces
Strike-Slip Faults
Strike-Slip faults occur when two plates slide past each other
Strike-Slip faults are caused by SHEAR forces
Let’s see it in action:
http://www.iris.washington.edu/gifs/animations/faults.htm
FoldsFolds are the result of FLOW. They are caused by
the same forces as faults, except they happen deep UNDERGROUND where it is very hot. Because it is hot, the rock bends instead of breaking.
There are two parts to a fold:The ANTICLINE is the top of the fold (think: ANTHILL)The SYNCLINE is the bottom of the fold (think: SIN)
ANTICLINES and synclines
Anticlines are at the top (they are the Anthills) Synclines are at the bottom (sin = hell = bott0m)
Now, go back through your sketches and
label your faults and folds
Ready to test your knowledge?