4 Folding And Faulting Flashcards
Tension
Divergent boundaries
Rocks stretch and thin
Normal fault
Graben fault
Compression
Convergent boundaries
Squeeze and shorten
Reverse fault
Thrust fault
Block mountain
Shearing
Transform boundaries
Opposite direction
Tear fault
Elements of a fold
Anticline-Rocks fold upwards-arch
Syncline-Rocks fold downwards-trough
Limbs-Join anticlines to synclines
Whats another word for syncline
Downfold
Whats another word for anticline
Upfold
List the types of fold
-Simple(symmetrical)
-Asymmetrical
-Overfold
-Recumbent(overturned)
-Overthrust
Simple fold
Limbs on either side have same steepness and length
Equal pressure has been applied on both sides
Asymmetrical fold
Limbs on either side of fold are didf in steepness and length
More pressure applied from one side than the other
Overfold
Both limbs moving in same direction
One limb pusing on top of the other one
More pressure has been applied on one side than ghe other
Recumbent(overturned) fold
Both limbs are movinf in the same direction and horizontal
Overthrust fold
Pressure is so great that a fracture occurs in the rock structure
One limb is pushed over the other
The strata are no longer aligned
3 folding movements
Caledonian- 400mya
Amorican- 250mya
Alpine- 30mya
Fold mountains created by Caledonian folding in ireland
Nephin Beg-Connaught
Derryveagh+Mourne Mnts-Ulster
Wicklow Mnts- Leinster
Mountains created by Armorican Folding in Ireland
Magcillycuddys Reeks-Munster
Galtees-Munster
Caha mountains- Munster
Comeragh Mountains-Munster
(Munster ridge and valley landscape)
Mountains formed by Alpine folding period
Himalayas
Rockies
Andes
How does faulting occur
Faulting occurs when rocks are put under stress at divergent,convergent or transform plate boundaries. COmpression TEnsion and SHear forces lead to fractures/fault lines forming along a line of weaknesss in the surface rocks of the earths crust. Large body of rock then either sunk lifted up or displaced.
Whats a fault plane
The plane along which the faulted block of ruck moves upwards or doenwards
Whats a fault scarp
Step/cliff or cliff like feature on the earths surface caused by failting
