Across
- 4. explosion The relatively rapid appearance, around 542 million years ago, of most major animal phyla, as demonstrated in the fossil record. This was accompanied by major diversification of other organisms.
- 7. The scientific study of prehistoric life.
- 8. sea vents A fissure in a planet's surface from which geothermally heated water issues.
- 9. of superposition A key axiom based on observations of natural history that is a foundational principle of sedimentary stratigraphy and so of other geology dependent natural sciences
- 10. tectonics A scientific theory that describes the large-scale motion of Earth's lithosphere.
Down
- 1. A period of time marked by distinctive character, events, changes on earth, etc.
- 2. theory Several key organelles of eukaryotes originated as symbioses between separate single-celled organisms.
- 3. generation an obsolete body of thought on the ordinary formation of living organisms without descent from similar organisms.
- 5. dating The science of determining the relative order of past events, without necessarily determining their absolute age.
- 6. The amount of time required for a quantity to fall to half its value as measured at the beginning of the time period.