Fossil Types
What is a fossil?
the preserved remains or traces of living things
What is the Absolute age?
the number of years that have passed since a rock formed
what is the Law of superposition?
To determine the relative age of a rock. It states that in undisturbed horizontal sedimentary rock layers the oldest is at the bottom Each higher layer is younger than the one below it.
What is a mold?
a hollow area in sediment in the shape of an organism or part of an organism
What is the Relative age?
the age of a rock compared to other rocks, i.e. older or younger than
Half-life
the time it takes for a radioactive element for half of the elements to decay
What is a Petrified Fossil?
a solid copy of the shape of an organism
What does Extinct mean?
when an organism no longer exists and will never again on earth
Radioactive Decay
elements that release particles of energy and they break down or decay over time. Atoms of one element break down to form atoms of another element.
What is a Carbon film
an extremely thin coating of carbon on rock
What are eras?
the time period between the Pre -Cambrian and present time period; Paleozoic, Mesozoic and Cenozoic
Eras
the time period between the Pre -Cambrian and present time period; Paleozoic, Mesozoic and Cenozoic
What is a Trace Fossil?
provides evidence of the activities of ancient organisms
What are Periods?
Eras that are subdivided. Many of the names come from places where fossils were discovered.
Uniformitarianism
the key principle that guides scientists when they make inferences about Earth's past and is states that the geologic processed that operate today also operated in the past