Earth History Test Crossword Review

fossils of organisms that were widely distributed but only lived during a short period of geologic time
shorter units of geologic time within each era
the Mesozoic era is known as the age of the _______
time it takes for half of the radioactive atoms in a sample of radioactive element to decay
The law of _______ states that in horizontal layers of sedimentary rock, each layer is older than the layer above it
the parts of an organism most likely to be preserved as fossils
preserved remains or traces of an organism
rock layers lost to erosion where new rock layers meet a much older rock surface
rock dating method that uses the amount of a radioactive isotope in an object
a rocks age compared to the ages of other rocks
term for when magma pushes into bodies of rock and cools and hardens
the era in Earth's history that was by far the longest
during Earth's history, there have been _______ recorded mass extinctions
scientists who study fossils collected from around the world
an organism that no longer exists on Earth