Geologic History Crossword

the preserved remains or traces of living things - a fossil type
a hollow area in sediment in the shape of an organism or part of an organism - a fossil type
a solid copy of the shape of an organism - a fossil type
fossils in which minerals replace all of an organism or part of an organism such as a dinosaur bone - a fossil type
an extremely thin coating of carbon on rock - a fossil type
provides evidence of the activities of ancient organisms - a fossil type
a process that preserves entire organisms, i.e. tar, tree resin, freezing - a fossil type
scientists that study fossils
the number of years that have passed since a rock formed
the age of a rock compared to other rocks, i.e. older or younger than
when an organism no longer exists and will never again on earth
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
a fossil that is widely distributed and and in existence for a relatively short period in geologic history. They are useful because they tell tell the relative age of the rock in which they are found.
a gap in the geological record that shows where rocks are lost due to erosion/ folding, etc...
it is the time it takes for a radioactive element for half of the elements to decay
elements that release particles of energy and they beak down or decay over time. Atoms of one element break down to form atoms of another element.
the time period between the Pre -Cambrian and present time period; Paleozoic, Mesozoic and Cenozoic
Eras that are subdivided. Many of the names come from places where fossils were discovered
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