Folding, Faulting And Doming Flashcards
Define deformation
Any change in shape or size of the rock as a result of stress. Results in folding, faulting and Doming
What are the Forces of deformation
Compression - folding
tension - stretching and thinning - faulting
shearing - faulting
What plate is compression associated with
Converging plates
What’s plates is tension associated with
Divergent plates
What’s plates is sharing associated with
Convergent and transform plates
What is a fold
A wave or bend in the stratified rock layers of the Earth’s crust
What is a fault
A cracker fracture with movement along both sides of the earths crust
In what direction are anticline folds going
Upwards
A shape
In what direction are syncline folds going
Downwards
V shape
Types of folds
Simple/ symmetric fold Asymmetric fold Overfold Recumbent fold Overthrust fold
Describe a symmetrical fold
Both limbs are equal steepness as compression is applied evenly from both sides
Describe an asymmetric fold
One limb is steeper than the other as more compression is applied to one side than the other
Describe an overfold
Compression from one side is so much greater than one limb is pushed over the other
Describe recumbent folds
Compression over time causes overfold to fold completely on top of each other
Describe an overthrust fold
Force of compression is so great that rocks break as one limb is pushed too far over the other
What rock is easiest to fold and why
Sedimentary as it’s the softest
Eras of folding
Caledonian
Amorican
Alpine
What plates caused the Caledonian folds
Collision of American and Eurasian plates
How long ago did the Caledonian folding take place
400 mya
Examples of Caledonian mountains
Twelve pins
Wicklow mountains
Appalachians, USA
How long ago did amorican folding begin
250 mya
What two plates cause the amorican folding
Eurasian and African plates
Examples of amorican folding
Ridge and Valley landscape in Munster
How long ago did the alpine folding occur
30 million years ago
What two plates chased the alpine folding
Collision of African and Indian plate with Eurasian
Examples of Alpine mountains
Himalayas
Rockies
Alps
3 types of fault are
Normal fault
Reverse fault
Tear fault
When do normal faults happen (what’s happening to the rock)
Tension stretches the rock
What’s a Rift Valley
Occurs when two faults occur side by side eg eats African Rift Valley
what is a block mountain or Horst
What’s left standing in between the two Rift valleys
Mountains with steep sided and flat top
Example of block mountain
Ox mountains in Sligo
Another name for Rift Valley
Graben
When does a tear vault happen
What’s happening to the rock
Rock is shearing as it’s pushed in opposite directions
Example of a tear fault
San Andreas fault
What occurs at a reverse fault (to the rock)
Rock is shortened by compression
What’s is a thrust fault
A type of reverse fault where the Angie of the fall is almost horizontal. The higher rock can be pushed forward
Impact of faulting on the landscape
A Rift Valley
What is a dome
A structure shaped like an upturned bowl
How is a dome formed
Great amounts of molten magma pushed up from under the earths crust pushing the overlying layers of rock upwards making a dome shape
Example of doming in Ireland
Slieve Bloom mountains, laois-Offaly
What is an orogeny
Process of folding
How long does folding take
Millions of years as plates move very slowly
Examples of Caledonian folding in Ireland
Dublin Wicklow mountains Leinster batholiths (doming)
Example off armorican folding in Ireland
Anticlines and synclines of Munster ridge and valley
Eg macgiillycuddyreeks (carentuhill)
River lee
