Geology & Paleontology Lecture Notes Review

Flashcards covering key vocabulary from the lecture on geology, paleontology, fossil preservation, bias in the fossil record, extinction, and stratigraphy.

Taphonomy

The field of study focusing on the processes of preservation and how they affect the information contained in the fossil record.

Fossilization

The process of transferring objects from the biosphere (living aspect of Earth) into the geological record (lithosphere/rock).

Biosphere

The living aspect of the Earth.

Lithosphere

The rock aspect of the Earth, where the geological record is found.

Bloat and Float

A type of taphonomic process where gases from decomposition cause an animal to float, potentially moving it away from its original depositional environment.

Unaltered Fossilization

A type of fossilization where the original hard parts, and sometimes soft parts, remain present in their original form.

Pleistocene animals

Ice Age animals, commonly found with unaltered fossilization due to freezing in permafrost.

Keratin

A type of tissue (e.g., on a duck-billed dinosaur's beak) that can sometimes be preserved unaltered in fossils.

Amber

Fossilized tree resin that often traps and preserves insects, feathers, or other small animal parts with original material.

DNA Half-Life

The very short time (approximately 520 years) over which DNA breaks down, meaning it is not preserved in very old fossils.

Coprolites

Fossilized feces, providing insights into the diet of ancient animals.

Permineralization

A common type of fossilization where original hard parts remain, and their pore spaces are filled with other minerals, making the fossil heavier.

Fighting Dinosaurs

A rare and famous example of exceptionally preserved fossils from Mongolia, showing a Velociraptor and Protoceratops locked in battle, indicating rapid burial.

Replacement Fossilization

A type of fossilization where the original hard material of an organism is completely replaced by another mineral.

Carbonization

A type of fossilization where compression leaves a thin film or stain of carbon on the rock, often preserving soft tissues or feathers.

Impression Fossilization

A type of fossilization where the original material is absent, but an impression (mold) is left in the sediment, often showing detailed external features like skin patterns.

Bias Against Becoming a Fossil

The extreme improbability for most organisms to be preserved in the fossil record, leading to significant gaps in understanding the history of life.

Fragments

The most common form in which extinct animal remains are found, consisting of small, incomplete pieces.

Articulated (bones)

Fossilized bones found in their correct anatomical order and orientation as they would have been in the living animal.

Rapid Rate of Sedimentation

The quick burial of an organism by a large amount of sediment, essential for the preservation of large, articulated skeletons (e.g., due to sandstorms, floods, mudflows).

Quiet Environment

A stable and undisturbed depositional setting (like a lake bed or lagoon) ideal for preserving entire small animals in articulation without disturbance.

Conglomerate

A sedimentary rock characterized by various sizes of poorly sorted particles, generally not ideal for articulated fossils but occasionally containing isolated hard parts like teeth.

Sandstone

A sedimentary rock made of smaller sand grains, good for finding various sizes of fossils, but the grains can sometimes damage small bones upon excavation.

Mudstone

A sedimentary rock known for excellent preservation, accommodating many fossil sizes and often containing bone beds, though not always articulated.

Lagerstatte

A German term for a sedimentary deposit exhibiting exceptional preservation, often containing numerous articulated fossils, soft tissues, and plant material (e.g., Burgess Shale, Green River formation).

Extinction

The permanent disappearance of a species.

Mass Extinction

A global-scale event characterized by a large number of species dying out within a relatively short geological time frame.

The Big Five

The five largest mass extinction events in Earth's history, including the Ordovician, Devonian, Permian, Triassic, and Cretaceous.

End-Permian Mass Extinction

Considered the worst mass extinction event in Earth's history, where 70-90% of life on Earth perished.

Stratigraphy

The field of geology that studies rock layers (strata), their ordering, distribution, and age relationships.

Steno's Laws

Fundamental principles of stratigraphy established by Nicolas Steno, including original horizontality, superposition, and lateral continuity.

Principle of Original Horizontality

Sediment is originally deposited in flat, horizontal layers.

Principle of Superposition

In an undeformed sequence of sedimentary rocks, the oldest layers are at the bottom and the youngest layers are at the top.

Outer Core

The liquid layer of Earth's core, primarily composed of melted iron and nickel, whose movement causes magnetic polarities.

Magnetic Polarities

The orientation of Earth's magnetic field, which has reversed multiple times throughout geologic history.

Magnetostratigraphy

A stratigraphy technique that uses the trace of magnetic orientation recorded in rocks at the time of their deposition to determine age and correlate layers.

Deep Time

The concept of geological time, spanning hundreds of millions to billions of years, which is often difficult for humans to fully grasp.

Relative Time

A method of dating that determines the sequence of events and the relative age of rock layers (e.g., 'A is older than B') without assigning specific numerical dates.

Numerical Time (Absolute Time)

A method of dating that assigns specific, measurable dates (in years or numerical units) to geological events or rock formations.

Unconformities

Erosional or weathering surfaces in the geological record that represent gaps in time or missing rock layers due to non-deposition or erosion.

Principle of Cross-Cutting Relationships

Any geological feature (like a fault, dike, or erosional surface) that cuts across pre-existing layers or structures must be younger than the features it cuts.

Biostratigraphy

A field of stratigraphy that uses the fossils preserved within rock layers to determine their relative age and correlate rock units between different geographical locations.

Correlation

The process of establishing equivalency in age or stratigraphic position between rock layers or geological events in different locations, often using biostratigraphy.

Geologic Time Scale

A chronological dating system that organizes Earth's history into hierarchical units of time, such as eras, periods, and epochs, based on stratigraphic and paleontological evidence.

Mesozoic Era

A major division of geologic time, often called the 'Age of Dinosaurs', subdivided into the Triassic, Jurassic, and Cretaceous Periods.

Epochs

Subdivisions of geologic periods (e.g., Early, Middle, Late Triassic), which are formal names and capitalized.

Cretaceous Period

A geologic period named from the Latin 'creta' (chalk), referring to the chalk deposits like the White Cliffs of Dover.

Jurassic Period

A geologic period first recognized in the Jura Mountains in Europe.

Triassic Period

A geologic period recognized from Europe for its threefold system, representing a three-part section of rock.