Flashcards in Fossil Record Deck (20)
a principle that states that geologic processes that occurred in the past can be explained by geological processes
a principle that states that geologic change occurs suddenly
the scientific study of fossils
any method of determining whether an event or object is older or younger than other events or objects
any method of measuring the age of an event or object in years
a principle that states that younger rocks lie above older rocks if the layers have not been disturbed
an atom that has the same number of protons (or the same atomic number) as other atoms of the same element do but that has a different number of neutrons (and a different atomic mass)
the process in which a radioactive isotope tends to break down into a stable isotope of the same element or another element
the time needed for half of a sample of a radioactive substance to undergo radioactive decay
the remains or physical evidence of an organism preserved by geological process
a fossilized mark formed in soft sediment by the movement of an animal
a mark or cavity made in a sedimentary surface by a shell or other body
a type of fossil that forms when sediments fill in the cavity left by a decomposed organism
a break in the geologic record created when rock layers are eroded or when sediment is not deposited for a long period of time
The extinction of a large number of species within a relatively short period of geological time, thought to be due to factors such as a catastrophic global event or widespread environmental change that occurs too rapidly for most species to adapt.
lasting for 55 million years during which dinosaurs and ammonites flourished.
a period of the Mesozoic Era, from 140 million to 65 million years ago, characterized by the greatest development and subsequent extinction of dinosaurs and the advent of flowering plants and modern insects.
a geological time during which a system of rocks formed. The trees are particularly important
a current period of geologic time, which began about 1.8 million years ago. ... The Quaternary period is the name for the time in which we live.