f r Flashcards
a principle that states that geologic processes that occurred in the past can be explained by current geologic processes
uniformitarianism
a principle that states that geologic change occurs suddenly
catastrophism
the scientific study of fossils
paleontology
any method of determining whether an event or object is older or younger than other event or objects
relative dating
a principle that states that younger rocks lie above older rocks if the layers have not been disturbed.
superposition
any method of measuring the age of an event or object in yeas
absolute dating
an atom that has the same number of protons
isotope
the process in which a radioactive isotope tends to break down into a stable isotope of the same element or another element
radioactive decay
the time needed for half of a sample of a radioactive substance to undergo radioactive decay
half-life
the remains or physical evidence of an organism preserved by geological processes
fossil
a fossilized mark that is formed in soft sediment by the movement of an animal
trace fossil
a mark or cavity made in a sedimentary surface by a shell or other body
mold
a type of fossil that forms when sediments fill in the cavity left by a decomposed organism
cast
a surface of contact between two groups of unconformable strata
unconformity
s a widespread and rapid decrease in the biodiversity on Earth
mass extinction
The Jurassic Period was the second segment of the Mesozoic Era. It occurred from 199.6 to 145.5 million years ago
Jurassic period
The Cretaceous Period was the last and longest segment of the Mesozoic Era
Cretaceous period
The Devonian is a geologic period and system of the Paleozoic, spanning 60 million years from the end of the Silurian, 419.2 million years ago
Devonian period
The Quaternary Period is divided into two epochs: the Pleistocene 2.588 million years ago to 11.7 thousand years ago
Quaternary period
The Permian period lasted from 299 to 251 million years ago* and was the last period of the Paleozoic Era
Permian period
