Geology Lesson 9b: Absolute and Geologic Time

Atoms of AA decay to atoms of BB with a half-life of 100,000 years. If there are 20,000 atoms of AA to begin with (and 0 atoms of BB), how long will it take for there to be 2,500 atoms of AA

300,000 years

What is the oldest eon?

Hadean

which geoscientists was the first to introduce the idea of geological (or deep) time

James Hutton

Which of the following radioactive isotopes is most useful for dating a very young sample (<20,000 years) of wood

carbon-14

Which geologic era do you live in

cenozoic

If you wanted to search for really, really old (billions of years old) rocks to date, would you go looking for continental rocks or ocean rocks?

continental rocks

order the divisions of geologic time from the longest to the shortest

eons, eras, periods, epochs

_________ are atoms with the same atomic number but different mass numbers

isotopes

The Phanerozoic eon is divided into three eras. What are they?

mesozoic, cenozoic, paleozoic

What scientific avenue of investigation gave scientists the best estimate of Earth's actual age?

radiometric dating