Across
- 3. this is when organism's are replaced by minerals
- 4. this happens when an insect is caught soft stick tree sap
- 5. 542 million to the present this eon is the eon we live in
- 10. the trace or remains of an organism that lived a long time ago
- 11. scientists believe that this was the death of dinosaurs
- 12. these climates sometime contain almost no bacteria
- 19. this paleontologist found enormous dinosaur nesting ground
- 20. this era was known as the age of the mammals
- 22. a subdivision of geologic period
- 24. in this era marine life began to flourished
- 25. this is an example of an index fossil
- 26. the largest division of geologic time
- 27. a principal that states the geologic change occurs suddenly
- 31. these fossils tell scientists that the sea level was much higher millions of years ago
- 32. a type of fossil that forms when sediments fill in the cavity left by a decomposed organism
Down
- 1. this happens because cold temperatures slow down decaying eg. a mammoth that was found frozen in Siberia still had fresh on him
- 2. a principle that states that geologic processes that occurred in the past can be explained by current geologic processes
- 5. 2.5 billion years ago to 542 million years ago the first organisms with well developed cells appeared
- 6. 3.8-2.5 billion years ago the earliest known rocks on Earth formed during this eon
- 7. this is the era where humans evolved
- 8. the age of the reptiles began in this era
- 9. this eon was around 4.6-3.8 years ago some of the rocks they have found from this eon are meteorites and rocks from the mooon
- 13. there is places where asphalt wells up on the earths surface in thick sticky pools and organisms and trapped
- 14. the death of every member of a species
- 15. the standard method used to divide the Earth's long natural history into manageable
- 16. a mark or cavity made in a shell or other body
- 17. this only gives only a rough sketch of the history of life on Earth
- 18. this is one of the places where Hutton observed results of geologic processes that lead him to find the principal uniformitarianism
- 21. a unit of geologic time into which eras are divided
- 23. a fossil that is found in the rock layers of only geologic age and that is used to establish the age of the rock layers
- 28. a fossilized mark that is formed in soft sediments by the movement of an animal
- 29. this is a person who studies fossils
- 30. a unit of geologic time that includes more two or more periods