ASBOG - Association of State Boards of Geology Field Geology and Mapping Questions and Answers 2

Question 1

When measuring a planar feature's orientation in the field using a Brunton compass, what two measurements are recorded?

Accepted Answer

Strike and dip

Answer

Latitude and longitude

Answer

Azimuth and plunge

Answer

Bearing and inclination

Question 2

On a geologic map, what does a hachure pattern (short lines pointing downslope) on a contact indicate?

Accepted Answer

A thrust fault with the upper plate moving in the hachured direction

Answer

A younger rock unit overlying an older one due to normal faulting

Answer

A nonconformity where igneous or metamorphic rock underlies sedimentary rock

Answer

An overturned fold limb

Question 3

A geologist measures multiple joint orientations in a rock outcrop and plots them on a stereonet. What does a tight cluster of poles represent?

Accepted Answer

A consistent joint set with nearly uniform orientation

Answer

A widely dispersed set of randomly oriented joints

Answer

A fold axis plunging at a steep angle

Answer

A shear zone with mylonitic fabric

Question 4

What is the purpose of a stratigraphic measured section in field geology?

Accepted Answer

To systematically document lithology, thickness, and vertical succession of rock units at a specific location

Answer

To determine the absolute radiometric age of rock units

Answer

To map the lateral extent of a single rock formation across a region

Answer

To collect geochemical samples for ore deposit evaluation

Question 5

When mapping in an area with poor outcrop, what remote sensing technique is most useful for identifying linear features that may represent faults or fractures?

Accepted Answer

Satellite-based synthetic aperture radar (SAR) or multispectral imagery

Answer

Ground-penetrating radar (GPR)

Answer

Seismic refraction surveys

Answer

Electrical resistivity tomography

Question 6

In describing sedimentary rocks in the field, a geologist notes 'graded bedding' in a sandstone sequence. What does this indicate about the depositional process?

Accepted Answer

Deposition from a waning turbidity current, with coarser grains settling first

Answer

Repeated cycles of wind deposition and erosion

Answer

Bioturbation mixing sediments of different sizes

Answer

Cross-bedding formed by migration of subaqueous dunes