CLUES TO EARTHS PAST Crossword

Remains, imprints, or traces of prehistoric organisms.
Remains of species that existed on Earth for a short period of time.
The time taken for any specified property to decrease by half.
Living thing such as animal, plant and human.
Somethings age, to the comparison to the ages of other things.
A thin film of carbon residue is left, forming a silhouette of the original organism
A hard part of something being dissolved and leaving behind a cavity.
Gaps in rock sequences are called _____________.
The solid, nonmetallic mineral matter of which rocks are made of.
The age, in years, of a rock or other object.
A method of dating geological or archeological specimens by determining the relative proportions of particular radioactive isotopes present in a sample.
A fossil of a footprint, trail or burrow.
Belonging to or forming the outer surface or structure of something.
Sometimes conditions allow ________ _________ of organisms to be preserved for millions of years.
A scientist who studies fossils.
Plant matter accumulating, over millions of years, these deposits become completely carbonized, forming ____.
The process in which something is being broken down.
A person, animal, or group living in a place or environment.
Rock formed when sediments are cemented and compacted.
An expert in or student of geology.