Practical Skills - Deformation Flashcards
1
Q
What is an unconformity?
A
- Change in dip direction
- Cross cutting
- Break in deposition/period of erosion
2
Q
What does an unconformity look like irl?
A
- fossils
- based conglomerate
- erosional surface (undulating)
3
Q
What is anticline?
A
- “n” shape
- oldest rock in the middle youngest on the outside
- on a cross section/map you draw a diamond shape
- dipping outwards
4
Q
What is a syncline?
A
- “u” shape
- youngest rock in the middle oldest on the outside
- on a cross section/map you draw a bowtie shape
- dipping inwards
5
Q
What does APT mean?
A
Axial plane trace- On a map
- describes 2 directions
6
Q
How can you spot asymmetry?
A
Outcrop width vary
7
Q
How can you spot symmetry?
A
Outcrop widths are the same
8
Q
How can you tell if a fault is normal or reverse?
A
F -Footwall
U- Upwards
N- Normal
H- Hanging wall
U- Upwards
R- Reverse
9
Q
Are the youngest rocks found on the downthrown or upthrown side?
A
On the downthrown side
10
Q
What would you look for in the field when identifying an u/c?
A
- Weathered surfaces below u/c
- fossils indicating a time gap
- included fragments of underlying rock in conglomerate above u/c
11
Q
Evidence for superposition?
A
Oldest is at the bottom unless overturned Can be confirmed by -Fossils -Sedimentary structures -Included fragment
12
Q
Evidence for faults?
A
- Displacement of rock units
- Ages of fossils very difficult on either side of fault
- Fault breccia
- Fault gouges
