The Mazama ash has been dated at numerous locations in the western US to 6900 years old. This means that if an archaeologist finds the Mazama ash in a stratified context, he or she knows that everything above it is less than 6900 years old, and everything below it is more than 6900 years old. The Mazama ash is an example of a:
A) colluvial sediment.
B) soil horizon.
C) marker bed.
D) sedimentary deposit that has been disturbed, resulting in reversed stratigraphy.

Question

Quizplus · Accepted Answer

The Mazama ash serves as a marker bed because it provides a specific time reference (6900 years old) that can be used to date other layers in a stratified context. Marker beds are identifiable layers of rock or sediment that have been spread over a wide geographical area by a specific event and can be used to date the layers of sediment/rock above and below them.

The Mazama Ash Has Been Dated at Numerous Locations in the Western