Chapter 4 History of the Earth

the time it takes for half of the radioactive atoms to decay is the elements

Radioactive dating works best with what type of rock?

A ____ is a gap in the geologic record where rock layers have been lost due to erosion

A fossil formed when minerals replace all or part of an organism is called a

Geologists use radioactive dating to

____ fossils are helpful to geologists because they reveal the relative ages of the rock layers

What is the age of an intrusion in relation to the rock layers through which is passes?

What has the study of fossils allowed scientists to do?

principle states that the geologic processes that change Earth today changed earth in the past

The relative age of a rock is

Scientists know how groups of animals changed over time by studying

Of the following methods, which led scientists to infer that earth is about 4.6 bil yrs old

Generally only the ____ parts of organisms become fossils