Ancient Crossword Puzzle

Remains of living things
A scientist that studies fossils
A fossil in which minerals replace all or part of an organism
A type of organism that no longer exist anywhere on earth
An igneous rock layer formed when magma hardens beneath earth's surface
The age of rock given the number of years since the rock formed
The geologic principle that states in horizontal and layers of sedimentary rock, each layer is older than the layer above it and younger than the layer below it
An igneous rock layer formed when lava flows onto earth's surface and hardens
Fossils of widely distributed organisms that lived during only one short period
A type of matter in which all the atoms are the same
A record of the geologic events and life forms in earth's history
One of the units of geologic time in which geologic divide eras
The time it takes for half of the atoms of a radioactive element to decay