Fossil Records Flashcards
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
is the science of determining the relative order of past events without necessarily determining their absolute age
absolute dating
is the process of determining an age on a specified chronology in archaeology and geology. Some scientists prefer the terms chronometric or calendar dating, as use of the word “absolute” implies an unwarranted certainty of accuracy.
superposition
for all linear systems, the net response caused by two or more stimuli is the sum of the responses that would have been caused by each stimulus individually.
isotope
each of two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei, and hence differ in relative atomic mass but not in chemical properties; in particular, a radioactive form of an element.
radioactive decay
is the process by which an unstable atomic nucleus loses energy by emitting radiation, such as an alpha particle, beta particle with neutrino or only a neutrino in the case of electron capture, or a gamma ray or electron in the case of internal conversion
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
is a fungus that grows in the form of multicellular filaments called hyphae. In contrast, fungi that can adopt a single-celled growth habit are called yeasts.
cast
an object made by shaping molten metal or similar material in a mold.
unconformity
a surface of contact between two groups of unconformable strata.
mass extinction
is a widespread and rapid decrease in the biodiversity on Earth. Such an event is identified by a sharp change in the diversity and abundance of multicellular organisms.
Jurassic period
was 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
was the last and longest segment of the Mesozoic Era. It lasted approximately 79 million years, from the minor extinction event that closed the Jurassic Period about 145.5 million years ago to the Cretaceous-Paleogene (K-Pg) extinction event dated at 65.5 million years ago
Devonian period
is a geologic period and system of the Paleozoic, spanning 60 million years from the end of the Silurian, 419.2 million years ago (Mya), to the beginning of the Carboniferous, 358.9 Mya. It is named after Devon, England, where rocks from this period were first studied.
Quaternary period
is divided into two epochs: the Pleistocene (2.588 million years ago to 11.7 thousand years ago) and the Holocene (11.7 thousand years ago to today). The informal term “Late Quaternary” refers to the past 0.5–1.0 million years.
Permian period
is a geologic period and system which spans 47 million years from the end of the Carboniferous Period 298.9 million years ago, to the beginning of the Triassic period 251.902 Mya. It is the last period of the Paleozoic era; the following Triassic period belongs to the Mesozoic era
