Earth's History and Changing Climate

Flashcards reviewing key concepts from lecture notes on Earth's history, relative and absolute dating, fossils, and the geologic timescale.

Who is the author of "The Theory of Earth"?

James Hutton

What is the main idea behind The Theory of Uniformitarianism?

Earth is very old and the same processes that operate today have operated throughout Earth’s long history. "The present is the key to the past."

Define Sedimentation.

Process by which solid particles settle out of a liquid or gas and accumulate on a surface

Define Plate Tectonic Movement.

Motion of the large, rigid plates that make up the Earth's lithosphere, which float on the semi-fluid asthenosphere beneath them.

List at least three components of Volcanic Activity.

Intruding magma, gas emissions, lava flows, ash eruptions, pyroclastic flows, volcanic debris

What is the rock cycle?

A series of processes that transform one rock type into another.

Name the three main types of rocks created in the rock cycle.

Sedimentary, metamorphic, and igneous rocks

Describe Biological Evolution.

The process by which living organisms change over successive generations through the gradual accumulation of heritable variations.

What is the rock record?

The geological history of Earth as preserved in layers of sedimentary rocks, igneous rocks, and metamorphic rocks.

What dating method places geological events in their order of occurrence?

Relative Dating

What dating method uses radiometric techniques to determine the number of years since a geologic event happened?

Absolute Dating

Define Outcrop.

Exposed bedrock on the surface of the Earth.

Define Strata.

Layers of rock or sediment that have been deposited over time.

Explain the Law of Superposition.

Unless sedimentary rock layers have been disturbed, the oldest rock layer is on the bottom.

Explain the Law of Original Horizontality.

Sedimentary rock layers were initially deposited flat on the ocean floor.

Explain the Law of Cross-Cutting Relationships.

Faults and igneous intrusions are younger than the layers they cut across.

Explain the Law of Inclusions.

Inclusions are older than the rock they are in.

What are unconformities?

Surfaces that represent a gap in the geologic record.

Describe a Nonconformity.

Younger sedimentary rocks overlay older, eroded igneous or metamorphic rocks.

Describe an Angular Unconformity.

Younger sedimentary rocks are deposited on tilted or folded layers of older sedimentary rocks.

Describe a Disconformity.

A gap in the geologic record between parallel layers of sedimentary rocks.

What is rock correlation?

A method used by geologists to establish the relationship between rock layers at different locations.

Define Fossils

Any preserved evidence of past life, typically found within sedimentary rocks, that provides information about ancient organisms and environments.

What is a Body Fossil?

Fossils that preserve parts of an organism's actual body.

Define Trace Fossils.

Indirect evidence of ancient life.

What are Coprolites?

Fossilized feces

What are Gastroliths?

Fossilized gizzard stones

How do Molds and Casts form?

Organism's remains decay and leave behind an impression in sediment (mold); mold later gets filled with minerals, creating a cast.

How do Petrified Fossils Form?

Organic material is replaced with minerals, turning it into stone.

How do Carbon Films form?

Organic material in an organism is compressed and heated, leaving behind a thin residue of carbon.

Give an example of Preservations related to fossils.

Organisms trapped in amber or frozen in ice.

What are Molecular Fossils?

Remnants of once-living organisms that have undergone chemical transformations over geological time scales.

What is the fossil record?

The collection of all known fossils, which are the preserved remains or traces of organisms that lived in the past.

What are index fossils?

Fossils of organisms that lived during specific time periods and have a wide geographic distribution.

State the Principle of Fossil Succession.

Fossil organisms succeed one another in a definite and determinable order, and therefore, any time period can be recognized by its fossil content.

What are Fossil Assemblages?

A collection of fossils found within a particular geological deposit or stratum.

Describe Transitional Fossils.

Intermediate forms that exhibit traits of both ancestral and descendant groups.

List four types of Bias that can occur in the fossil record.

Preservation bias, taphonomic bias, temporal bias, sampling bias

Define Isotope.

Atoms of an element which have different numbers of neutrons in their nuclei.

What is radioactive decay?

A spontaneous process by which an unstable isotope releases radiation to become more stable.

Describe Alpha Decay.

An atomic nucleus emits an alpha particle (a helium-4 nucleus consisting of two protons and two neutrons), resulting in the transformation of the original nucleus into a different nuclide.

Describe Beta Decay.

Emission of energetic beta particles (electrons or positrons) resulting in the transformation of the original nucleus.

Describe Gamma Decay.

An unstable atomic nucleus releases gamma rays, resulting in the transformation of the original nucleus.

Define Half-life.

The time it takes for half of the atoms in a sample of a substance to undergo radioactive decay.

Define Luminescence.

The emission of light by a substance when it is stimulated by energy sources such as heat or light.

What is Optically Stimulated Luminescence (OSL) Dating used for?

To determine the age of sediments and geological deposits, as well as archaeological artifacts buried in sedimentary contexts.

What is Thermoluminescence (TL) Dating typically used for?

Materials such as pottery, ceramics, and burnt stones in archaeological contexts.

What is Dendrochronology?

A dating technique that uses the analysis of tree rings to determine the age of wooden objects or structures.

What is the purpose of a Tree Core?

A cylindrical section of wood extracted from the trunk of a tree for dendrochronological analysis.

What is Cross-Dating?

Dendrochronologists compare ring patterns with the master chronology.

What is Dendroclimatology?

Subfield of dendrochronology, focuses on using tree-ring data to reconstruct past climate conditions.

What is Varve Chronology used for?

Establish precise and detailed chronological sequences of sedimentary deposits, particularly in glacial and lake environments.

What is the Geologic Timescale?

A chronological framework that divides Earth's history into distinct intervals based on major geological and biological events.