ASBOG - Association of State Boards of Geology Geomorphology and Quaternary Geology Questions and Answers 2

Question 1

What is the primary mechanism by which meandering rivers migrate laterally across their floodplains over time?

Accepted Answer

Lateral erosion of cut banks and deposition on point bars

Answer

Vertical incision into bedrock

Answer

Mass wasting of valley walls into the channel

Answer

Avulsion — sudden channel abandonment and creation of a new course

Question 2

Which geomorphic surface is characterized by a broad, gently sloping bedrock erosion surface that truncates older structures and is mantled by thin residual sediments?

Accepted Answer

Pediment

Answer

Alluvial fan

Answer

Peneplain

Answer

Fluvial terrace

Question 3

What Quaternary dating method is based on the accumulation of cosmogenic nuclides (such as 10Be) in surface rocks exposed to cosmic ray bombardment?

Accepted Answer

Cosmogenic nuclide exposure age dating

Answer

Radiocarbon (14C) dating

Answer

Optically stimulated luminescence (OSL) dating

Answer

Uranium-series dating

Question 4

What is the primary distinction between an alluvial fan and a debris fan in semi-arid mountain terrain?

Accepted Answer

Alluvial fans are dominated by water-laid sediments; debris fans by mass movement deposits

Answer

Alluvial fans are depositional while debris fans are erosional surfaces

Answer

Alluvial fans form only in humid climates; debris fans only in alpine environments

Answer

Alluvial fans are steeper than debris fans

Question 5

What does a river's longitudinal profile describe, and what is a knickpoint?

Accepted Answer

The elevation change along the river from headwaters to mouth; a steep reach or waterfall where the graded profile is interrupted

Answer

The cross-sectional shape of the channel; a point where channel width suddenly increases

Answer

The gradient of the floodplain; a location where the floodplain narrows

Answer

The sinuosity of the river; a sharp meander bend

Question 6

Which glacial depositional landform is an elongated, streamlined hill of till that formed parallel to ice flow direction?

Accepted Answer

Drumlin

Answer

Esker

Answer

Kame

Answer

Kettle