ASBOG Field Geology and Mapping 4

Question 1

During field mapping, a geologist finds that the same formation appears twice on a traverse crossing a valley. Which structure MOST likely explains this repetition?

Accepted Answer

Thrust fault or overturned fold

Answer

Repetition of the same formation in the same order across a traverse typically indicates a thrust fault or tight fold that has duplicated the section.

Question 2

A Brunton compass is used to measure the trend and plunge of a lineation. After sighting along the lineation downhill, the geologist reads 035° and 28°. This is reported as:

Accepted Answer

Trend 035°, plunge 28°

Answer

Lineations are described by trend (azimuth of horizontal projection) and plunge (inclination below horizontal), written as trend/plunge.

Question 3

Which of the following best describes the purpose of a pace-and-compass traverse in geologic mapping?

Accepted Answer

To locate position and record observations where GPS is unavailable or unreliable

Answer

A pace-and-compass traverse allows the geologist to track position and record observations in areas where GPS signals are poor or unavailable.

Question 4

On a standard USGS 7.5-minute topographic map used for geologic mapping, what does a brown dashed line typically represent?

Accepted Answer

An unpaved road or trail

Answer

On USGS 7.5-minute topographic maps, brown dashed lines represent unpaved roads, jeep trails, or foot trails.

Question 5

A geologist maps a pluton and finds that the surrounding sedimentary rocks are recrystallized adjacent to the contact. This metamorphic aureole suggests:

Accepted Answer

The pluton intruded the sedimentary rocks and baked them

Answer

A metamorphic aureole indicates contact metamorphism, confirming that the pluton intruded the host rocks after they were deposited.

ASBOG - Association of State Boards of Geology Practice Test

ASBOG - Association of State Boards of Geology Practice Test

ASBOG Field Geology and Mapping 4