Study Guide Lect 2

Neptunism

A geological theory proposed by Abraham Werner in 1787, stating all rocks were formed from a primeval ocean.

Catastrophism

A theory by Baron George Cuvier suggesting rocks formed through catastrophic events such as volcanism and earthquakes.

Uniformitarianism

A theory developed by James Hutton that became the backbone of geological thought, asserting that processes observed today have always worked in the same way.

Stratification

The layering of rock sequences, can include igneous, sedimentary, and metamorphic rocks.

Contact

The interface between different lithologies.

Lithology

The physical and chemical characteristics of a rock type.

Formation

A definable stratigraphic unit of rock that has a name and distinctive boundaries.

Stratigraphic sequence

All the vertical changes in rock formations at a specific location.

Hiatus

A significant break in deposition indicating missing geologic time.

Unconformity

Occurs when there is a break in deposition due to the passage of significant geologic time.

Transgression

Geological process involving the rise of sea level and the inundation of land areas.

Regression

The geological process where sea level falls, causing land to be exposed.

Biostratigraphy

Correlation using fossils to determine the age and equivalency of rock layers.

Index fossil

Fossils that were abundant, easily recognizable, and existed for a relatively short geologic timeframe, useful for dating rock layers.

Superposition

The principle that older layers of rock are found below younger layers in a stratigraphic sequence.

Photochemical Dissociation

The breakdown of water vapor by the sun to produce ozone during the Archean eon.

Stromatolites

Layered sedimentary formations created by the activities of cyanobacteria.

Cyanobacteria

Photosynthetic bacteria that play a crucial role in the production of oxygen and the formation of stromatolites.

Polymers

Molecules made up of long chains of monomers; examples include DNA and RNA.

Epeiric sea

Shallow seas that cover continental landmasses.

Paleomagnetism

The study of ancient Earth's magnetic field to determine past plate movements.

Cratonic sequence

A cycle of transgression and regression during the Paleozoic, outlined by Lawrence Sloss.

Sauk Sequence

The first major transgression onto the North American Craton from the late Proterozoic to early Ordovician.

Feedback

The system of solving problems through the ongoing process of assessment and adaptation in scientific research.

Lateral gradation

Changes in lithology that occur horizontally due to varying depositional environments.

Taconic Orogeny

A mountain-building event during the Ordovician caused by the subduction of the Iapetus oceanic plate beneath the Laurentian plate.

Mountain-building episodes

Events related to tectonic forces that result in the uplift of mountain ranges.

Absolute age dating

Techniques used to determine the actual age of a rock or fossil.

Transgressions and regressions

Refers to the rise and fall of sea levels and their impact on sediment deposition.

Glacial melting effects on sea level

The rising of sea levels due to the melting of glaciers during warmer periods.

Fossil correlation

The comparison of two stratigraphic columns using fossils to establish age equivalency.

Range zone

The time span during which a particular index fossil existed in the geological past.

Erosion

The process by which surface materials are worn away and transported elsewhere.

Deposition

The process by which sediments settle out of the transporting medium (water, air, etc.).

Conformable stratigraphic sequences

Sequences of rock layers that show no significant breaks in deposition.

Index fossils

Fossils that are used to define and identify a particular time period in geological history.

Importance of stromatolites

Among the oldest known fossils, important for understanding early life and the Earth's atmosphere.

Origin of life requirements

Presence of appropriate elements and an energy source to promote the synthesis of organic molecules.