Chapter 19.1

Question 1

extinct

Answer 1

Species is one that has died out

Question 2

paleontologist

Answer 2

Researchers who study fossils to learn about ancient life

Question 3

relative dating

Answer 3

Places rock layers and their fossils in a temporal sequence

Question 4

index fossil

Answer 4

Distinctive fossils used to establish and compare the relative ages of rock layers and the fossils they contain

Question 5

radiometric dating

Answer 5

Relies on radioactive isotopes, which decay, or break down, into stable isotopes at a steady rate

Question 6

half-life

Answer 6

Time required for half of the radioactive atoms in a sample to decay

Question 7

geologic time scale

Answer 7

Geologist and paleontologists have built a time line of Earth’s history

Question 8

eons

Answer 8

Divided into eras

Question 9

hadean, archean, proterozoic, phanerozic

Answer 9

The names for Eons

Question 10

era

Answer 10

Subdivided into periods, which range in length from nearly 100 million years to just under 2 million years.

Question 11

paleozoic, mesozoic, cenozoic

Answer 11

Eras

Question 12

period

Answer 12

Division of geologic time into which eras are subdivided

Question 13

cambrian, ordovican, silurian, devonian, carboniferous, permian, triassic, jurassic, cretaceous, paleogene, neogene, quaternary,

Answer 13

Periods

Question 14

plate techtonics

Answer 14

Movement as a result of solid “plates” moving slowly, as little as 3 cm a year, over Earth’s mantle

Question 15

climate change

Answer 15

Temperature increases or decreases according to the earth’s position