Geology: Relative Age Dating Flashcards

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Questions and Answers

What is relative age dating?

Mapping the layers found in rocks

Studying the erosion of rocks

Determining the age of rocks by comparing them with other rocks and features nearby (correct)

Assigning specific times to events represented by changes in rock type

What does the Law of Superposition state?

The oldest rocks are on the bottom in undisturbed rock layers.

What is an inclusion?

A piece of an older rock that becomes part of a new rock.

What is an unconformity?

A surface where rock has been weathered and eroded away, producing a break in the rock record. Signup and view all the answers

Identify three major types of unconformities.

Nonconformity Signup and view all the answers

What happens in a disconformity?

Younger sedimentary layers are deposited on top of older eroded sedimentary layers. Signup and view all the answers

What occurs in an angular unconformity?

Sedimentary layers are deposited on top of tilted or folded sedimentary layers that have been eroded. Signup and view all the answers

Explain nonconformity in geology.

Younger sedimentary layers are deposited on older igneous or metamorphic rock layers that have been eroded. Signup and view all the answers

What is correlation in geology?

Matching rocks and fossils from separate locations. Signup and view all the answers

What is an index fossil?

A species or organism that existed for a short time, was abundant, and had a widespread distribution. Signup and view all the answers

What are the Latin root words for layers?

Strata, strato, stratum Signup and view all the answers

What is stratigraphy?

The scientific mapping, describing, and interpreting of the layers found in rocks. Signup and view all the answers

What does the Law of Cross-Cutting Relationships state?

Features like canyons and faults that cut across sedimentary layers must have occurred after those layers were deposited. Signup and view all the answers

What is the Law of Inclusions?

The rock fragments that make up sedimentary rocks must be older than the sedimentary rock containing the fragments. Signup and view all the answers

What does the Law of Original Horizontality state?

Sedimentary strata are originally deposited in horizontal layers. Signup and view all the answers

What is the Law of Lateral Continuity?

Sedimentary rocks are laterally continuous over large areas. Signup and view all the answers

What does the Law of Flora/Faunal Succession describe?

Fossils of more archaic organisms are succeeded by fossils of organisms with more modern traits. Signup and view all the answers

Define xenolith.

A 'foreign' piece of country rock trapped inside of an igneous rock. Signup and view all the answers

The _____ is the older, pre-existing rock that is displaced by intrusive igneous bodies.

country rock Signup and view all the answers

Identify types of igneous intrusions.

All of the above Signup and view all the answers

Study Notes

Relative Age Dating

Determines the age of rocks by comparing them to other nearby rocks and geological features.

Law of Superposition

In undisturbed rock layers, the oldest rocks are found at the bottom, and the youngest at the top.

Inclusion

Refers to a piece of older rock encapsulated within a newer rock, typically in sedimentary contexts.

Unconformity

A surface indicating weathering and erosion that creates a gap in the geological record.

Types of Unconformities

Disconformity: Younger sedimentary layers on eroded older horizontal layers.
Angular unconformity: New layers deposited atop tilted or folded and eroded layers.
Nonconformity: Younger sedimentary layers placed over older, eroded igneous or metamorphic rocks.

Correlation

The process of matching rocks and fossils from different locations.

Index Fossil

A fossil from a species that existed for a brief time, was abundant, and had a widespread distribution, aiding in dating geological layers.

Stratigraphy

Involves mapping and interpreting various layers of rock.

Sedimentary Petrology

The study dedicated to understanding sedimentary rocks and their characteristics.

Absolute Age Dating

Involves assigning specific timeframes to geological events indicated by changes in rock types.

Erosion

The geological process of wearing away or transporting sediments through wind, water, or gravity.

Deposition

The process where sediments settle after being transported in a fluid medium.

Nicholas Steno

Recognized as the father of stratigraphy, laying foundational concepts for relative age dating.

Law of Cross-Cutting Relationships

States that geological features like faults and igneous intrusions must be younger than the features they cut through.

Law of Inclusions

Developed by James Hutton, indicating that rock fragments within sedimentary rocks are older than the rocks themselves.

Law of Original Horizontality

Most sedimentary layers are deposited horizontally, and any angularity implies post-depositional processes.

Law of Lateral Continuity

Sedimentary rocks generally extend laterally over large areas until they thin out or encounter a barrier.

Law of Flora/Faunal Succession

Developed by William "Strata" Smith; states that simpler organisms precede more complex ones in the fossil record.

Xenolith

Refers to a fragment of country rock embedded within igneous rock.

Country Rock

The older rock, typically igneous or metamorphic, that is altered or displaced by intrusive bodies.

Types of Igneous Intrusions

Include batholiths, plutons, dikes, sills, and laccoliths, each characterized by their unique formation and structure.

Geological Features

Examples such as igneous intrusions, faults, canyons, and unconformities can disrupt older geological structures and records.

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Description

Test your understanding of relative age dating and key geological principles with these flashcards. Learn about concepts such as the Law of Superposition and inclusions in rock layers. Perfect for geology students or enthusiasts looking to reinforce their knowledge.