1. The Rock and Fossil Record
Unit 10.1
The Rock and Fossil Record

2. Fossil = evidence of ancient organism
the remains or impression of a prehistoric organism preserved in petrified form or imprinted in rock.

3. Preserved signs of activity or behavior of an organism
Trace fossils
Preserved signs of activity or behavior of an organism

4. Index fossil
a fossil that is useful for dating the organism and area where it is found.
The Tropites pictured here are dated between 230 and 208 million years ago

5. Relative Age
The geologic age of a fossil organism is defined relative to other organisms rather than in terms of years.
This is based on the law of superposition = older rocks are at the bottom

6. Absolute Age
The geologic age of a fossil expressed in units of time, usually years.
Also known as actual age.

7. Radioactive
isotope
dating
 having an unstable nucleus that decomposes automatically loosing an electron to become stable
This process takes the same amount of time-ALWAYS
The isotope decay is used to determine the age of an object

8. 10.2 Geologic Time

9. Precambrian
The earliest period of time billion and 541 million years ago
Earth was formed
the first single celled organisms were born
about 90 % of Earth’s history

10. Supercontinent All continents massed together
Plate tectonics slowly move them apart

11. cyanobacteria
Single celled organism that obtain their energy through photosynthesis and produce oxygen

12. Paleozoic Era
time of ancient life lasted from 544 to 245 million years
is divided into six periods: Cambrian, Ordovician, Silurian, Devonian, Carboniferous, Permian
Break up of Rodinia
Formation of Pangaea

13. Mesozoic era 248 million to 65 million years ago
is divided into three periods:
Triassic, Jurassic, Cretaceous
Break up of Pangaea begins
Flowering plants begin

14. Cenozoic era
spans about 65 million years, extinction of non-avian dinosaurs to the present
sometimes called the Age of Mammals, because the largest land animals would have been mammals during that time

15. Ice Age the time period that began about 2.6 million years ago
glaciers covered most of Earth.

16. Unit 10.3 Earth: Past, Present, and Future

17. Glacier
a slowly moving mass of ice formed by the accumulation and compaction of snow on mountains or near the poles

18. A cycle when ice sheets melted, and the land rebounded
Interglaciers
A cycle when ice sheets melted, and the land rebounded