Clues to Earth's Past Crossword

Remains, imprints, or traces if prehistoric organisms that can tell when and where organisms once lived and how they lived.
Fossils in which the spaces inside are filled with minerals from groundwater.
Thin film of carbon residue preserved as a fossil.
A type of body fossil that forms in rock when an organism with hard parts is buried.
A type of body fossil that forms when crystals fill a mold or sediments wash into a mold and harden into a rock.
Remains of species that existed on Earth.
States that in undisturbed rock layers.
The age of something compared with other things.
Gap in the rock layer that is due to erosion or periods without any deposition.
Age, in years, of a rock or other object; can be determined by using properties of the atoms that make up materials.
Release of nuclear particles and energy from unstable atomic nuclei.
Time needed for one half of the mass of a sample of a radioactive isotope to decay.
Process used to calculate the absolute age of rock by measuring the ratio of parent isotope to daughter product in a mineral and knowing the half-life of the parent.
Principle stating that Earth processes occurring today are similar to those that occurred in the past.