ASBOG Field Geology and Mapping 2

Question 1

When measuring strike using the right-hand rule, the geologist holds their right hand along the strike line with fingers pointing in which direction?

Accepted Answer

So the thumb points in the dip direction

Answer

The right-hand rule states that when you align your right hand along the strike with the thumb pointing in the dip direction, fingers curl in the direction of dip.

Question 2

A geologist records a fold whose axial plane dips 30° and whose hinge line plunges 20°. This fold is best described as:

Accepted Answer

Inclined plunging

Answer

An inclined plunging fold has an axial plane that dips at an intermediate angle and a hinge line that plunges in the same vertical plane.

Question 3

On a geologic map, a contact that is concentric with topographic contours and closes on itself typically represents:

Accepted Answer

An intrusive body or dome

Answer

Circular to elliptical contacts that parallel topographic contours indicate an intrusive body such as a pluton or a structural dome.

Question 4

Which approach is MOST appropriate when mapping in areas with poor outcrop exposure?

Accepted Answer

Use float, soil color, and vegetation patterns to infer lithology

Answer

Indirect evidence such as float, soil characteristics, and vegetation changes helps infer subsurface geology where outcrops are absent.

Question 5

The apparent dip of a bed is always _____ the true dip, except when the cross-section is cut perpendicular to strike.

Accepted Answer

Less than

Answer

Apparent dip is always less than true dip because you are measuring across an oblique section rather than perpendicular to strike.

ASBOG - Association of State Boards of Geology Practice Test

ASBOG - Association of State Boards of Geology Practice Test

ASBOG Field Geology and Mapping 2