AntA01 Lecture 3 – Archaeological Methods
- Survey – go looking for bones and fossils
- Why people did what they did in the past is impossible to know
Where did people live?
- Archaeological sites: an area where people conducted a certain behaviour such as a village or
even like a butchery site
- Artifacts: any artifact made by those in our lineage
- Ecofact: animal bone remains, plant remains, something that tells us about the environment
- Features: things that you cannot pick up and take to the lab eg: the remains of a fire pit or the
remains of a barn – for this you need to take lots of pictures and notes etc.
- How you find archeological sites
- We know humans need certain things to survive eg: fire and water
- Oral traditions – people whose ancestors know where they lived etc. such as troy
- This man looked at the remains of Troy and found that after 6 layers he found the city of Troy as
told in the story in the Iliad.
- Take your PhD boots and walk for miles looking for something
- It is hard to get permits to dig so its something that you need to look into
- For villages that you find that are underground, there are certain things that you can use to help
see it eg: electrical Resistivity Survey, Proton Magnetometry, etc.
- Focus on areas with certain rocks and things and analyze them chemically to look at the
signature to see if this is the right area to excavate in
What materials did they leave behind?
- Maintain the provenience: an artifacts 3D position which shows it position to every other
- Assemblage: all the artifacts found in the same provenience
- You stop digging when you reach the change in color of soil which marks a new strata
DFM: site struction
- Intricate map of where people were living
- Blue- where people threw their refuse
- Red is where they dumped their clay - It is important to note all the little things because you destroy the site while excavating so you
can never go back.
When did human activities occur?
- Relative Dating: first 150 yrs, archeologists used this
- Absolute dating methods: newer methods
Dates in the Distant Past
- BP means years before 1950 AD since this is when they invented radio carbon dating (this tells
you that they used radio carbon dating to find this)
- If you see something that states an absolute date (eg: 1942) this should be seen with skepticism
since it is usually a range or average.
- Whatever is in the bottom is older than what is on the top
- However, there are exceptions such as glaciers, volcanoes, earthquakes, mountain building,
rodents (bring things from different layers around)
- Concept that things come into fashion and go out of fashion because something more
fashionable comes about
- Image shows different styles of grave stones from 1720 to 1820
- Each row shows 100% and column shows style of grave stone
- This map is called a battleship map
- This is relative not absolute
- Things like coins have dates, journals diaries, books, newspaper these give us the absolute
dates of the objects
- However, these things only give us the maximum age of the area since things can be passed
down through generations so a coin found to be 2000 years old might be in a house abandoned
only 100 years ago.
- Every year a tree lays down a new ring – each ring come out in different thicknesses depending
on the quality of life of the tree during that year.
- If you find a relatively recent deceased tree then you can take a archeological piece of wood and
then take a living tree and match the piece of wood to the rings on the living tree - This can go back 1200-1500 years
- Carbon 12 is the most abundant, most stable and most common.
- Isotope is carbon 13 so it weighs a little more
- Carbon 14 – the one we are interested in – it is extremely rare and it decays
- All living things have carbon
- Carbon 14 is only created in the upper atmosphere. Nitrogen in the atmosphere is bombarded
with cosmic rays which add this extra electron to make it carbon 14. Then the C14 tries to get rid
of the electron which causes it to decay back to N14.
C14 has a decay rate so that it doesn’t matter how much it has, it will always lose half its amount in that
- Carbon half life is 5,730 yrs
- Half-life measured through mass spectrometer
- MAKE SURE YOU UNDERSTAND THIS FOR MIDTERM
- This works for anything that has carbon in it
- How do we know how much carbon was there initially?
- There is a constant amount between C12 and C14 ratio so it doesn’t matter what the initially
was, you can calculate the age by looking at this ratio
- When you see a radio carbon date tell you how much carbon is missing – so never assume this
to be 100% accurate
- The problem with this is that it only work with living things and also only work till 50,000 years
ago because you run out of carbon 14
Potassium Argon Dating
- A lot of the very old fossils are found in Africa where there are many volcanoes
- For this we can use potassium a