Clues to Earth's Past Crossword

Preserved remains or evidence of ancient living things
The idea that conditions and organisms on Earth change in quick, violent events
a method used by geologists to fill in the missing gaps in an area's rock record by matching rocks and fossils from separate locations
a fossil copy of an organism made when a mold of the organism is filled with sediment or mineral deposits
the fossilized carbon outline of an organism or part of an organism
the numerical age, in years, of a rock or object
the time required for half of the amount of a radioactive parent element to decay into a stable daughter element
a fossil representative of a species that existed on earth for a short period of time, was abundant, and inhibited many location
a piece of an older rock that becomes a part of a new rock
atoms of the same element that have different numbers of neutrons
a scientist who studies fossils
the principle that in undisturbed rock layers, the oldest rocks are on the bottom
the preserved evidence of the activity of an organism
the impression of an organism in a rock
the process by which an unstable element naturally changes into another element that is stable
the age of rocks and geologic features compared with other nearby rocks and features
a principle stating that geologic processes that occur today are similar to those that occur in the past
a surface where rock has eroded away, producing a break, or gap, in the rock record