ASBOG Geomorphology and Quaternary Geology 2 — Questions and Answers
Question 1: Which landform is produced when a river deposits sediment at its mouth as it enters a standing body of water?
- Alluvial fan
- Delta (Correct answer)
- Bajada
- Pediment
Correct answer: Delta
A delta forms when a river loses velocity and deposits sediment as it enters a lake or ocean.
Question 2: The Wisconsin glaciation in North America ended approximately how many years ago?
- 5,000 years ago
- 10,000 years ago (Correct answer)
- 18,000 years ago
- 25,000 years ago
Correct answer: 10,000 years ago
The Wisconsin glacial stage ended approximately 10,000 years before present, marking the start of the Holocene.
Question 3: A 'roche moutonnée' is a glacially sculpted bedrock feature characterized by:
- Steep upstream face and smooth downstream face
- Smooth upstream face and steep downstream face (Correct answer)
- Symmetrical rounded sides on both ends
- A flat top and vertical sides
Correct answer: Smooth upstream face and steep downstream face
Roche moutonnée has a smooth, striated stoss (upstream) side shaped by abrasion and a rough, steep lee (downstream) side from glacial plucking.
Question 4: What term describes the maximum elevation above which snow accumulation exceeds ablation on a glacier?
- Firn line
- Equilibrium line altitude (Correct answer)
- Snowfield boundary
- Ablation zone limit
Correct answer: Equilibrium line altitude
The equilibrium line altitude (ELA) separates the accumulation zone above from the ablation zone below on a glacier.
Question 5: Which Quaternary dating method relies on the accumulation of cosmogenic nuclides in surface rocks exposed to cosmic radiation?
- Optically stimulated luminescence (OSL)
- Surface exposure dating (Correct answer)
- Amino acid racemization
- Uranium-series dating
Correct answer: Surface exposure dating
Surface exposure dating measures cosmogenic nuclides like ¹⁰Be and ²⁶Al that accumulate in rock surfaces exposed to cosmic rays.
Question 6: A pediment is best described as:
- A depositional fan at the base of a mountain
- A gently sloping erosional bedrock surface at a mountain front (Correct answer)
- A flat-topped resistant rock butte
- A wave-cut terrace along a coastline
Correct answer: A gently sloping erosional bedrock surface at a mountain front
A pediment is a low-angle erosional surface cut into bedrock at the base of a mountain range, often veneered with thin alluvium.
Question 7: Which term refers to wind-deposited silt that forms thick, widespread blankets of sediment?
- Colluvium
- Loess (Correct answer)
- Tillite
- Fluvial terrace fill
Correct answer: Loess
Loess is aeolian silt transported and deposited by wind, forming extensive blankets across many mid-latitude regions.
ASBOG Geomorphology and Quaternary Geology 2
Which landform is produced when a river deposits sediment at its mouth as it enters a standing body of water?