fossil record Flashcards
(20 cards)
uniformitarianism
The theory that changes in the earth’s crust during geological history have resulted from the action of continuous and uniform processes.
Catastrophism
The theory that changes in the earth’s crust during geological history have resulted chiefly from sudden violent and unusual events.
paleontology
The branch of science concerned with fossil animals and plants.
relative dating
the process of determining if one rock or geologic event is older or younger than another, without knowing their specific ages—i.e., how many years ago the object was formed.
absolute dating
The process of determining an age on a specified chronology in archaeology and geology.
superposition
any sequence of layered rocks, a given bed must be older than any bed on top of it.
isotope
Isotopes are variants of a particular chemical element which differ in neutron number, and consequently in nucleon number.
radioactive decay
the process by which an unstable atomic nucleus loses energy by radiation.
half-life
the time taken for the radioactivity of a specified isotope to fall to half its original value.
fossil
the remains or impression of a prehistoric organism preserved in petrified form or as a mold or cast in rock.
trace fossil
a fossil of a footprint, trail, burrow, or other trace of an animal rather than of the animal itself.
mold
Mold is a type of fungus that grows indoors and outdoors. It thrives in moist, warm conditions
cast
when an animal, plant, or other organism dies, its flesh decays and bones deteriorate due to chemical reactions; minerals gradually enter into the cavity, resulting in a cast
unconformity
a surface of contact between two groups of unconformable strata.
mass extinction
A mass extinction is usually defined as a loss of about three quarters of all species in existence across the entire Earth over a “short” geological period of time.
Jurassic period
The Jurassic is a geologic period and system that spanned 56 million years from the end of the Triassic Period 201.3 million years ago to the beginning of the Cretaceous Period 145 Mya.
Cretaceous period
The Cretaceous is defined as the period between 145.5 and 65.5 million years ago,* the last period of the Mesozoic Era, following the Jurassic and ending with the extinction of the dinosaurs (except birds).
Devonian period
The Devonian, part of the Paleozoic era, is otherwise known as the Age of Fishes, as it spawned a remarkable variety of fish.
Quaternary period
The Quaternary Period is famous for the many cycles of glacial growth and retreat, the extinction of many species of large mammals and birds, and the spread of humans.
Permian period
The Permian period, which ended in the largest mass extinction the Earth has ever known, began about 299 million years ago. The emerging supercontinent of Pangaea presented severe extremes of climate and environment due to its vast size.
