Name the time in Earth's history: Clue #1: 4.6 billion to 542 million years ago Clue #2: no Oxygen in air Clue #3: Very primitive single celled and multi-cellular life forms
What is Precambrian?
Name the time in Earth's history: Clue #1: end of era caused by an asteroid colliding with Earth #2: Age of Reptiles; Clue #3: Known as "middle life" it includes the age of the dinosaurs
What is the Mesozoic era?
Name the time in Earth's history: Clue #1: 65 million years ago to today Clue #2: fossils are in the top layer
What is the Cenozoic era?
What characteristics should an index fossil have?
located in 1 layer, spread over multiple geographic sites/areas
The law that states that in horizontal layers of sedimentary rock, the oldest layers are at the bottom, and the layers get younger towards the top
What is the Law of Superposition?
Name the time in Earth's history: Clue #1: Humans first appeared
What is the age of mammals?/Cenozoic Era
A diagonal crosscut through horizontal layers is older or younger than the rock that it cuts through?
What is younger?
A gap in the sequence of rocks in a geologic column
What is an uncomformity
The first trace of life on earth can be traced back to how many billion years ago?
3.8 billion years ago.
When organisms began using photosynthesis 2.5 billion years ago, what happened as a result?
Oxygen increased in the atmosphere
What is a scientist who studies fossils called?
Paleontologist