Transcript FOLDS AND STRUCTURES DUE TO FOLDING

FOLDS AND STRUCTURES
DUE TO FOLDING
Folding generally takes place in areas of
sedimentary rocks that have been laid down in
horizontal layers called strata.
When compression produces thrust
[convergence], the earth folds along lines of
strength and weakness.
This creates long ranges of FOLD MOUNTAINS
– Alps, Himalayas, Rockies…
The Alps
Compressed into folds
PARTS OF A FOLD:
ANTICLINE: the layers of rock that
bend up.
ANTICLINE
SYNCLINE: The layers of rock that
bend down
SYNCLINE
SYNCLINE
Anticline
Anticline(s)
Faulting –
adjacent surfaces are displaced relative
to one another
Normal Fault
In normal faulting, the hanging
wall block moves down
relative to the footwall block.
Normal faults are associated
with crustal TENSION.
Normal Fault…
Reverse Fault
In reverse faulting, the hanging wall
block moves up relative to the
footwall block.
Reverse faults are associated with
crustal COMPRESSION and are
also known as thrust faults.
Components of
FAULTING…
A horst occurs when a mass of
the earth's crust that lies
between two faults and is higher
than the surrounding land.
A graben is an elongated depression between geologic faults.
Strike-slip Fault
In strike-slip faulting, the two blocks move
either to the left or to the right relative to one
another.