Geologists think that Earth is how old?

Another name for cyanobacteria, the earliest evidence of ancient life, is

Sedimentary layer A is found above sedimentary layer B, and the two are separated by a horizontal layer of ash, C. Therefore, the order from oldest to youngest is

The Cenozoic is a(n)

The Triassic period is part of which era?

The Jurassic is a(n)

The smallest units of geologic time are the

The Paleozoic is a(n)

The largest units of geologic time are the

Wood from an ancient stump has a ratio of carbon-14 to carbon-12 that is one-eighth that of new wood. About how old is the stump? (Carbon-14’s half-life is 5730 years.)