Biology
Ecology Notes
Dating the layers:
1) Hyraceum (OK)
- Dssie poo.
- Dassie urine and faeces are formed in mounds.
- Carbon dating gives accurate dates. (lower & middle layers)
- This preserves plants, pollen and many other creatures.
- Allows a researcher to go back roughly 4000 yrs from present.
2) Dendrochronology (OK)
- Uses tree rings.
- Tree rings are laid down seasonally based on conditions affecting
the trees and therefore treesthat were alive at the same time period
have same pattern.
- Uses computer programs to map the ring patterns of trees all over
- Fragments of fossil tree can be sectioned and their age read using a
backward stepping library of rings patterns from all trees.
- Makes use of the oldest orgaism on the planet the Bristlecone Pine,
over 4000 yrs old.
- Method allows to go back 135000 yrs.
3) Relative Dating
- Relies on the fact that all fossil deposits are layered.
= TOP layers are the youngest & lower layers get older and older
- These fossils are called TYPE fossils…
= Fossils that occur ONLY in one layer of the fossil record to identify
the layers that we are looking at.
=
- The layer is then dated to the age that we know that fossil represents
from other, more reliably dated layers in which that fossil occurs.
4) Radio Carbon Dating (ABSOLUTE)
- A half-life method using the half-life of carbon 14.
- Carbon 14 is a radioactive isotope of Carbon 12.
- C14 decays into C12 and the quantity can be measured & worked
backwards to the point where the carbon was laid down.
- This type of dating is accurate for short-term time lines of
approximately 1 M years.
After that it becomes inaccurate.
Ecology Notes
Dating the layers:
1) Hyraceum (OK)
- Dssie poo.
- Dassie urine and faeces are formed in mounds.
- Carbon dating gives accurate dates. (lower & middle layers)
- This preserves plants, pollen and many other creatures.
- Allows a researcher to go back roughly 4000 yrs from present.
2) Dendrochronology (OK)
- Uses tree rings.
- Tree rings are laid down seasonally based on conditions affecting
the trees and therefore treesthat were alive at the same time period
have same pattern.
- Uses computer programs to map the ring patterns of trees all over
- Fragments of fossil tree can be sectioned and their age read using a
backward stepping library of rings patterns from all trees.
- Makes use of the oldest orgaism on the planet the Bristlecone Pine,
over 4000 yrs old.
- Method allows to go back 135000 yrs.
3) Relative Dating
- Relies on the fact that all fossil deposits are layered.
= TOP layers are the youngest & lower layers get older and older
- These fossils are called TYPE fossils…
= Fossils that occur ONLY in one layer of the fossil record to identify
the layers that we are looking at.
=
- The layer is then dated to the age that we know that fossil represents
from other, more reliably dated layers in which that fossil occurs.
4) Radio Carbon Dating (ABSOLUTE)
- A half-life method using the half-life of carbon 14.
- Carbon 14 is a radioactive isotope of Carbon 12.
- C14 decays into C12 and the quantity can be measured & worked
backwards to the point where the carbon was laid down.
- This type of dating is accurate for short-term time lines of
approximately 1 M years.
After that it becomes inaccurate.
