Vocab for Science

4. an animal without a backbone.
5. A record of the geologic events and life forms in Earth's history.
7. a vertebrate whose temp is determined by its environment
11. a vertebrate whose body temp is regulated by heat and has skin covered with hair or fur
12. when many types of livng things become extinct
14. an animal with a backbone.
15. a vertebrate whose body temperature is determined by the temperature of its environment, and that lives its early life in water and its adult life on land
16. One of the three long units of geologic time between the Precambrian and the present.

1. The process of determining the age of an object using the half-life of one or more radioactive istopes.
2. The preserved remains or traces of an organism that lived in the past.
3. The age of a rock given as the number of years since the rock formed.
6. The age of a rock compared to the ages of other rocks.
8. The geologic principle that states that in horizontal layers of sedimentary rock, each layer is older than the layer above it and younger than the layer below.
9. A gap in the geologic record that shows where rock layers have been lost due to erosion.
10. The process of determining the radioactive istopes.
13. One of the units of geologic time into which geologists divide eras.