9.1 Relative Dating Principles

The number of years that have passed since an event occured

The chronological order of events, determined by placing rocks and structures in their proper sequence or order

A principle which states that in any undeformed sequence of sedimentary rocks, each bed is older than the one above and younger than the one below. Founded by Nicolas Steno

A principle by which layers of sediment are generally deposited in a horizontal or nearly horizontal position.

A principle which states that sedimentary beds originate as continuous layers that extend in all directions until they grade into a different type of sediment or thin out at the edge of a sedimentary basin correlation of rocks can occur over large distances

The geologic principle which states that geologic features that cut across rocks must form after the rocks they cut through.

Fragments of one rock unit that have been enclosed within another

The principle which states that a rock mass adjacent to one containing inclusions must have been there first in order to provide the rock fragments and is therefore the older rock mass The rock mass that contains inclusions is the younger of the two.

Refers to rock layers that were deposited without interruption

A surface that represents a break in the rock record, caused by erosion and nondeposition

An unconformity in which the older strata dip at an angle different from that of the younger beds It indicates that during the pause in deposition, a period of deformation and erosion occurred.

A gap in the rock record that represents a period during which erosion rather than deposition occurred

Older metamorphic or intrusive igneous rocks are overlain by younger sedimentary strata