1. Fossils
SOL #10

2. Fossil
Remains, impression, or other evidence preserved from preexisting life
Hard parts of organism are more likely to fossilize than soft parts
Most are found in sedimentary rock

3. Types of Fossils Mineral replacement Carbon film Mold & cast
Minerals in soil replace soft parts in bones, teeth, or shells
Carbon film
Carbon imprint of item left behind
Mold & cast
Imprint in ground that gets filled in by sediment to form a cast
Original remain
Soft parts of item preserved
Trace fossil
Evidence of an organism (footprints)
Trails & burrow
Type of trace fossil

5. Index Fossils
Fossils from species that were only around for a short period of time

6. Dating Fossils Relative age Absolute age
Comparing ages (X is older than Z)
Law of superposition-undisturbed layers of rock=older on bottom, younger on top
Absolute age
Age in # of years
Radioactive decay

7. Radioactive Decay Break down of isotopes Alpha/Beta decay Half life
Beta loose electron: alpha loose 2 n & 2 p
Half life
Time it takes for ½ atoms to decay
Radiocarbon Dating
Using C-14 to determine age of item

9. Unconformities Gaps in rocks
Due to erosion or periods of time where no deposition occurred

10. Fossils in VA
Mainly in Coastal Plains, Valley & Ridge, and App. Plateau
Most are marine org.
Paleozoic, Mesozoic, & Cenozoic Eras