Historical Geology Review

These flashcards cover key concepts and principles of Historical Geology, including geochronology, dating methods, and geological principles.

What is geochronology?

Geochronology is the science of determining the age of rocks, fossils, and sediments using signatures inherent in the rocks themselves.

What distinguishes absolute geochronology from relative geochronology?

Absolute geochronology uses radioactive isotopes to assign specific ages, while relative geochronology uses fossils, paleomagnetism, and stable isotope ratios to determine the age in relation to other objects.

What does the Law of Superposition state?

The Law of Superposition states that in any undisturbed sequence of rocks, the oldest layer is at the bottom and the youngest layer is at the top.

Define isotopes.

Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons.

What is the principle of intrusion?

The principle of intrusion states that an intrusive rock body is always younger than the rocks it invades.

What is radiometric dating?

Radiometric dating is a method used to determine the age of rocks and fossils by measuring the concentration of radioactive isotopes and their decay products.

What is a half-life?

A half-life is the amount of time required for half of the original parent atoms in a radioactive sample to decay into daughter atoms.

Define the concept of 'missing time' in the rock record.

Missing time refers to gaps in the geological record where no sediments were deposited or previous sediments were eroded away, leaving a period of time unrecorded.

What is the principle of faunal succession?

Faunal succession is the principle that fossils succeed one another in a definite, irreversible, and determinable order, allowing for relative dating of rock layers.

Explain the difference between relative and absolute dating with an example.

Relative dating provides an age in relation to other objects (e.g., saying you are older than your sibling), while absolute dating assigns a specific number as the date of an object (e.g., stating your exact age in years).