rock and fossil Flashcards
unifornitarianism
the idea that the same geologic processes have been at work throughout earth’s history. Suggests the earth is very old and was challenged by many early scientist.
catatrophism
idea tat geologic change occurs suddenly, suggests that the earth could only be a few thousand years old.
paleontology
the scientific study of fossils
relative dating
any method of determining whether an event or object’s older or younger tan other events or objects
absolute dating
any method of measuring the age of an event or object in years.
superposition
a principle that states that younger rocks lie above older rocks if the layers have not been disturbed.
isotope
an atom that have the same number if protons as other atoms of the same element do but that has a different number if neutrons.
radioactive decay
the process in which a radioactive isotope tends to break down into a stable isotope of the same element or another element.
half life
the times needed for half of a sample of a radioactive substance to undergo radioactive decay
fossil
the remains or physical evidence of an organism preserved by geologist process.
trace fossil
a fossilize mark that is formed in soft sediment by the movement of an animal
mold
a mark or cavity made in sediment surface by a shell or other body.
cast
a type of fossil that forms when sediment fill in the cavity left by a decomposed organism
unconformity
a break in the geologic record created when rock layers are eroded or when sediment is not deposited for a long period of time.
mass extinction
usually caused by major climate change
