EASC 1002 Midterm Lab Exam Vocabulary

Comprehensive vocabulary flashcards covering rock types, relative dating principles, strike and dip measurements, cephalopod classifications, and facies relationships for the EASC 1002 Midterm Lab Exam.

Greywacke

A specific rock hand specimen type required for identification in Lab 1 beyond the standard kits.

Pegmatite

A specific rock hand specimen type required for identification in Lab 1 beyond the standard kits.

Andesite with plagioclase phenocrysts

A specific rock hand specimen type required for identification in Lab 1.

Relative dating

A method used to sequence units and deformation to determine the order of geologic events without necessarily determining an absolute age.

Absolute dating

The process of determining an approximate numerical age for an archaeological or geological specimen.

Law of original horizontality

A principle of relative dating stating that layers of sediment are originally deposited horizontally under the action of gravity.

Unconformities

Geologic contacts representing a break in the geologic record where rock layers are missing due to erosion or a period of non-deposition.

Inclusions

A relative dating principle stating that fragments of one rock unit contained within another must be older than the rock unit they are in.

Declination

The angular difference between magnetic north and true north that must be set on a compass before taking measurements.

Strike

The orientation of a planar feature measured as the intersection of a horizontal plane with the tilted surface.

Dip

The angle of inclination of a planar feature measured from the horizontal plane.

Right hand rule (RHR)

The convention used with a compass-clinometer to report strike and dip measurements systematically.

Cephalopod types

Categories of fossils that include Nautiloid, Goniates, Ceratites, and Ammonite.

Walther’s Law

A geological principle stating that the vertical succession of facies reflects environments that were once laterally adjacent to one another.

Transgression

A facies relationship occurring when sea level rises relative to the land and the shoreline moves toward higher ground.

Regression

A facies relationship occurring when sea level falls relative to the land and the shoreline moves seaward.

Lithofacies

A body of rock with specified characteristics that reflect a particular depositional environment, used in stratigraphic correlation.

Biofacies

A body of rock identified by its fossil content, used to complete stratigraphic correlations.

Way-up structures

Geologic features used to identify the original vertical orientation and flow direction of rock samples or diagrams.