Unit 4 Flashcards
Geologic Time Scale, Relative and Absolute Age Dating, Fossils and Fossilization Processes, Precambrian Era, Paleozoic Era, Mesozoic Era, Cenozoic Era.
A scientist who studies fossils to learn about organisms that lived long ago.
Paleontologist
Remains; impression, track; or other evidence or ancient organisms.
Fossil
Fossils of widely distributed organisms that lived during only one short period.
Index Fossils
Mark or track of an ancient animal preserved in sedimentary rock.
Trace Fossil
A type of fossil consisting of an extremely thin coating of carbon on rock.
Carbon Film Fossil
Remains of living things that have been replaced by minerals and thus turned to stone.
Petrified Fossil
A space in a rock that has the shape of the remains of a living thing that once occupied that space.
Fossil Mold
A model in the shape of a living thing or its remains.
Fossil Cast
Method of describing the age of one object or even compared to another object or even.
Relative Age
Age in years of a geologic even fossil, or rock, usually found by radioactive test.
Absolute Age
An igneous rock layer formed when lava flows onto Earth’s surface and hardens.
Extrusion
An igneous rock that forms when magma hardens beneath Earth’s surface.
Intrusion
A place where an old, eroded rock surface is in contact with a newer rock layer.
Unconformity
The process at work today happened the same way in the past.
Principle of Uniformitarianism
In undisturbed layers, older rocks will be under younger rocks.
Superposition
Over time, elements breakdown by releasing particles and energy.
Radioactive Decay
The time it takes for half of the radioactive atoms to decay.
Half-Life
A random change in a gene.
Mutation
Theory, based on scientific evidence, that describes how organisms change over many generations.
Evolution
Condition in which there are no more living members of a species.
Extinct
An organism that has not suffered extinction- still living.
Extant
Animals with backbones- fish, amphibians, reptiles, mammals, birds.
Chordate
An animal without a backbone.
Invertebrate
Role that a species plays in a living community or ecosystem.
Niches
Organisms that cannot live in high oxygen environments.
Anaerobes
Event in geologic history when many species of organisms died out over a short period of time.
Mass Extinction
Largest division of geologic time, lasting many hundreds of millions of years.
Eon
Division of geologic time lasting several hundreds of million of years; shorter than an eon, longer than a period.
Era
Unit of geologic time lasting tens of millions of years, part of an era, and longer than an epoch.
Period
Smallest division of geologic time; lasts several million years.
Epoch
