Earth and Space

3. a solid inorganic substance of natural occurrence
6. discharge of electricity
10. the process by which organic matter exposed to minerals over a long period is turned into a stony substance
11. one species disappear completely
12. this mass extinction is the disappearance of more than 50% of fish, sponges and corals
14. a specialist in paleontology
15. during this mass extinction 50% of animals species disparaged
17. any of the pieces of hard, whitish tissue making up the skeleton in humans and other vertebrates
18. is the mass extinction when 96% of marine species and 75% species disappeared

1. remains or impression of a prehistoric organism preserved in petrified form or as a mold or cast in rock Sun the star around which the earth orbits
2. what makes the sedimentary rock? Pressure the continuous physical force exerted on or against an object by something in contact with it
4. the sudden occurrence of a violent discharge of steam and volcanic material
5. this mass extinction lost 70% of marine species
7. the action or process of adapting or being adapted
8. rock formed from consolidated clay sediments
9. a long and distinct period of history with a particular feature or characteristic
13. the process of eroding or being eroded by wind, water or other natural agents
16. during this mass extinction is the disappearance of the dinosaurs