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Flashcards in Fossils Deck (24)
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1

What is a fossil

Any preserved trace left by an rganisms that lived in the past

2

What are types of fossil

Burrows
Teeth
Bones
Footprints

3

How are fossils formed

Formed when hard body parts or organisms such as bone or teeth are buried by drifting sand, deposited by rivers, volcanic ash

4

Requirements for fossil formation

1. Quick burial
2. Presence of hard body parts
3. Absence of decay microorganisms
4. Long period of being left undisturbed

5

Where are fossils often found?

1. Near lakes and rivers due to build up of sediment when flooding occurs
2. In caves because limestone may be deposited around dead organisms or the roof of the cave may collapse
3. Or found by chance or excavation of a site

6

What are artefacts

Objects that have been deliberately made by humans

7

Examples of artefacts

Stone tools
Beads
Carvings
Cave paintings

8

How does the fossil record provide evidence for evolution

It provides evidence of which organisms lived on earth in the past and establishes links between species to determine commmon acenstry

9

What are the two types of dating

Absolute dating
Relative Dating

10

What is absolute dating?

Finding the actual date of a specimen

11

What is relative dating?

Tells us if the sample is older or younger than the other

12

What is potassium argon dating

It is dating volcanic rock next to the fossil not the fossil itself

13

What is the P-A dating based on?

Based on the decay of radioactive potassium 40 to form calcium and argon

14

What is P-A dating half-life?

Potassium has a half-life of 1.25-1.3B years so, over a period of 1.25B years, half the original potassium -40 would have decayed

15

How can P-A age fossils?

The ratio of potassium 40 to argon 40 determines the age in a rock sample, the ratio of argon compared to potassium the older it is

16

What is the limitations of P-A

1. Not all rocks are suitable because not all rocks are volcanic
2. Can only date a rock sample, not the fossil itself
3. Only date samples past 200 000 years
4. Must be suitable rock of the same age as the fossil

17

What is radio carbon dating based on?

Based on the decay of radioactive isotope of carbon -14 to nitrogen

18

What is the half-life of R-C dating?

Half life is 5730 years, so over a period of 5730 years there will be half the original carbon 14 amount

19

How can R-C dating help to date fossils?

The ratio of carbon -14 to carbon 12 can help to determine the age of the fossil

20

What is the limitations of R-C dating?

1. Required 3 grams of organic material
2. After 70 000 years the quantity of carbon -14 is too small to be used, can only date back than 60,000 years

21

What is stratigraphy

The study of layers

22

What are the principles of stratigraphy

1. Principle of rock strata
2. Principle of correlation of rock strata

23

What is the principle fo rock strata

Assumes layers of the rock, the layers at the top are the younger than the below

Distortions in the earth's crust do occur and the sequence of rock layers can be different

24

What is the principle of correlation of rock strata

Have to match layers of rock from different areas to determine the youngest and oldest

This can be done by examining the rock and studying the fossils it contains

Particular fossils are widely distributed and were present on Earth for only a short time which can be used as index fossils