Across
- 3. the sudden occurrence of a discharge of volcanic material
- 6. the fourth period of the paleozoic period
- 7. the continuous physical force exerted against an object
- 10. part of the skeletal system
- 11. rock formed from consolidated clay sediments
- 12. the star around which the earth orbits
- 13. the occurrence in which a large number or all of a certain species dies off
- 15. a person who studies fossils
- 16. a group of organisms consisting of similar individuals capable of exchanging genes and interbreeding
Down
- 1. the gradual destruction or diminution of something by wind, water, or other natural agents
- 2. the second period of the paleozoic era
- 4. a change or the process of change by which a species becomes better suited to its environment
- 5. a discharge of electricity
- 8. the process in which bones are replaced by minerals to form rocks
- 9. a long and distinct period of history with a particular feature or characteristic
- 14. the remains or impression of an animal preserved in rock