Stratigraphy and Evolutionary Theory in Earth History

A set of flashcards covering key terms and definitions from the lecture notes about stratigraphy and evolutionary theory.

Stratigraphy

The study of rock layers (strata), including their composition, origin, age relationships, and geographic extent.

Lithostratigraphy

A subfield of stratigraphy that classifies rock layers based on their lithologic properties.

Biostratigraphy

A subfield of stratigraphy that uses fossils to date and correlate rock layers.

Chronostratigraphy

A subfield of stratigraphy that focuses on the age of rock layers and their temporal relationships.

Marine Transgression

An event during which sea levels rise, leading to the flooding of coastal land.

Marine Regression

An event during which sea levels fall, exposing previously submerged land.

Unconformity

A gap in the geological record due to erosion or non-deposition of sediment.

Walther's Law

The principle that states that sedimentary facies successions reflect changes in the environment and can be used to interpret past depositional environments.

Fossil record

The history of life as documented by fossils, which provide evidence for evolutionary history.

Great Oxidation Event

A time in Earth's history (\sim2.4 billion years ago) when atmospheric oxygen levels increased due to photosynthesis by cyanobacteria.

Ediacaran Fauna

The first complex multicellular life forms appearing in the fossil record, primarily during the Ediacaran Period.

Abiogenesis

The process by which life arises naturally from non-living matter, such as simple organic compounds.

Natural Selection

The mechanism by which organisms better adapted to their environment tend to survive and produce more offspring.

Speciation

The formation of new and distinct species as a result of evolutionary processes.

Homologous Structures

Anatomical features in different species that share a common ancestry, but may serve different functions.

Analogous Structures

Structures in different species that perform similar functions but do not share a common ancestry.

Paleogeography

The study of historical geography, particularly the geographic distribution of landmasses and oceans over geological time.

Fossilization

The process by which organic material becomes a fossil through mineralization and other geological processes.

Principle of Superposition

In an undeformed sequence of sedimentary rocks, each layer of rock is older than the one above it and younger than the one below it.

Index Fossil

A fossil that is useful for dating and correlating the strata in which it is found, due to its widespread geographic distribution and short temporal range.

Radiometric Dating

A method used to date rocks and other objects based on the decay rates of radioactive isotopes.

Cambrian Explosion

The rapid diversification of most major animal groups that occurred approximately 541 million years ago.

Mass Extinction

A widespread and rapid decrease in the biodiversity on Earth, often resulting in the loss of 75% or more of species within a geologically short period.

Convergent Evolution

The process whereby organisms not closely related independently evolve similar traits as a result of having to adapt to similar environments or ecological niches.

Relative Dating

The process of determining if one rock or geological event is older or younger than another, without dating it numerically.

Principle of Original Horizontality

States that sedimentary layers are originally deposited horizontally.

Principle of Lateral Continuity

States that sedimentary layers extend laterally in all directions until they thin out or are stopped by a barrier.

Principle of Cross-Cutting Relationships

States that a geological feature that cuts across another is younger than the feature it cuts through.

Principle of Faunal Succession

States that fossilized organisms succeed each other in a definite and determinable order, allowing for the relative dating of strata.

Angular Unconformity

An unconformity where horizontally parallel strata of sedimentary rock are deposited on tilted and eroded layers.

Disconformity

An unconformity between parallel layers of sedimentary rocks that represents a period of erosion or non-deposition.

Nonconformity

An unconformity where sedimentary rocks lie directly on top of igneous or metamorphic rocks.

Trace Fossil

Indirect evidence of ancient life, such as tracks, burrows, or coprolites, rather than the organism itself.

Body Fossil

The preserved remains of an organism's actual body or skeleton, such as bones, shells, or teeth.

Geological Time Scale

A system of chronological dating that relates geological strata to time, describing events in Earth's history.

Genetic Drift

Random changes in the frequency of alleles (gene variants) in a population, particularly significant in small populations.

Gene Flow

The transfer of genetic material from one population to another, which can alter allele frequencies in both populations.

Macroevolution

The origin of amphibians from fish is an example of this.

Allopatric speciation

The emergence of new species from geographic isolation.

Theory of Evolution

States that organisms have changed since life originated.

Mountain building.

What event is most likely to lead to allopatric speciation?

Vestigial structures

Human wisdom teeth and tailbones are examples of these, as their functionality has changed over time.

Phyletic gradualism

The gradual accumulation of minor changes that bring about a transition from one species to another.

Kingdom, phylum, class, order, family, genus, species.

Correct taxonomic hierarchy (largest to smallest)

Genetics/Molecular Biology (He did use comparative anatomy, classification, geographic distribution, embryology, and the fossil record).

What evidence did Charles Darwin not use to support the theory of evolution?

Evolution is driven by random mutation and natural selection.

Which statement about evolution is most accurate?

True.

Is an order lower in rank than a class but higher than a family in biological classification?

True.

Can evolutionary trends be reversed?

False.

Does evolutionary change always occur slowly, over long periods of time?

Species.

What defines populations that can interbreed and produce fertile offspring?

True.

Do sharks and dolphins show convergent evolution due to similar features despite being distantly related?

True.

Are a bat's wing and a bird's wing are examples of analogous structures?

Cladistics

The biological analysis in which organisms are grouped together based on derived characteristics.

Microevolution

Evolutionary changes in living populations that take place within a species.

Paleontology

The scientific study of life history as revealed by fossils.

Biogeography

The field that studies the geographic distribution of ancient and present-day organisms, providing strong evidence for evolution.

True.

Did the Grenville Orogeny involve the closing of an ocean basin along the eastern margin of North America?

Sedimentary and volcanic rocks.

What types of rocks compose greenstone belts?

False.

Was Earth a hot, barren, waterless planet during the Archean eon?

False.

Have Precambrian shield areas been tectonically active since the Phanerozoic?

False.

Are most Precambrian rocks devoid of fossils because oceans didn't exist then?

False.

Have oxygen levels in Earth's atmosphere been stable throughout its history?

True.

Did banded iron formations precipitate in oxygen-rich ocean waters?

Laurentia.

What landmass began splitting apart along the Midcontinent Rift approximately 1.1 bya?

Anaerobic organisms

Organisms that need no oxygen to survive.

Snowball Earth hypothesis

States that widespread glaciers covered Earth and froze the seas during the Proterozoic.

Zircon

A mineral that has given scientists the best ages for very early crustal rocks, with the oldest being 4.4 billion years.

Earth's first atmosphere

Likely consisted of hydrogen and helium, the most abundant gases in the universe.

Hadean

The earliest informal interval of geologic time that began with the birth of the planet (approximately 4.6 - 4.0 bya), also described as the time in Earth's history before 4 billion years (4000 m.y.).

Extremely bright Sun.

Which event did not occur in the Hadean (approximately 4.6 - 4.0 bya)?

Granite and gneiss.

What are the most common Archean-age rocks?

Canadian Shield

The exposed part of the North American craton.

Outgassing

The accumulation of an early atmosphere by the release of gases from Earth's interior during volcanism.

Sandstone, shale, and limestone.

What rock types are found along passive continental margins?

Pannotia

The supercontinent that reassembled after the fragmentation of Rodinia.

North America.

Where are rocks that were formerly part of Laurentia mostly found today?

Ophiolites

Slices of ancient oceanic crust composed of mafic-ultramafic complexes, tectonically emplaced onto the continents.

Ultramafic rock.

What was the earliest crust probably composed of?

Subaqueous volcanic eruptions.

What do pillow lavas found in greenstone belts suggest?

Animal burrowing in sediments.

How is the beginning of the Cambrian period recognized in the geologic record?

Grenville orogeny

The final large-scale episode of Proterozoic deformation in Laurentia.

Cyanobacteria

Fossils of these suggest that oxygen-producing organisms had evolved by the Archean.