Geologic Cross-Section Relative Dating (08 Ordering)

Vocabulary flashcards defining the rock units, features, and relative age ordering rules from the geological cross-section diagram in question 08.

Geologic cross-section (08 Ordering)

A visual diagram illustrating rock strata, an intrusion, and structural relationships used to sequence geological events from the youngest at the top to the oldest at the bottom.

Youngest event

The most recently occurring geological event, designated to be ordered at the top of the sequence.

Oldest event

The earliest occurring geological event, designated to be ordered at the bottom of the sequence.

Layer S

The uppermost horizontal rock layer exposed at the ground surface, incised by a central erosional valley or canyon.

Layer G

The horizontal pebble- or clast-bearing rock stratum located directly beneath Layer S.

Rock unit R

An igneous rock body that cuts across layers B, T, N, and H, containing xenoliths/inclusions and bordered by contact metamorphism.

Inclusions (in Unit R)

Fragments of pre-existing rock layers (such as H, N, and T) that are incorporated inside igneous body R.

Layer C

The uppermost dipping rock layer in the tilted sequence on the left side of the cross-section, overlying Layer K.

Layer M

The lowermost dipping rock layer within the tilted sequence on the left side of the cross-section, underlying Layer K.

Layer B

The deepest dipping rock layer visible in the stratified sequence on the bottom-right side of the cross-section, positioned beneath Layer T.