Fossils Unit LO 1-11 Quiz

Question 1

Uniformitiasm vs Catastrophism

Answer 1

Newer idea that earth is old and everything now happened in the past.
Earth is young and created from catastrophes.

Question 2

Outrcrop and Strata

Answer 2

Exposed bedrock on the surface of the Earth.
Layers that have been deposited over time.

Question 3

Faults and intrusions

Answer 3

Something cuts through a rock layer, igneous rock being forced up into another rock layer

Question 4

Stratigraphic Column

Answer 4

Layers that are in the same relative order in a sequence that must have been in line with each other.

Question 4

5 lays of relative dating and what they mean

Answer 4

1. Law of Superposition - oldest layers on bottom, younger as you go up
2. Law of Original Horizontality - Layers are almost always originally horizontal
3. Law of cross-cutting - faults and intrusions are younger than the layers that they cut across
4. Law of inclusions - inclustions are older than the rock that they are in
5. Law of Unconformities - Surface that represents a gap in the rock formation (either rock was not depositied or there was erosion)

Question 5

Steps to an unconformity

Answer 5

1. Deposition of a sediment
2. Rocks are tilted (deformation)
3. Erosion occurs, removing rocks and creating an uneven surface
4. More rocks layers are deposited straight onto the slanted, eroded layer, causing an unconformity

Question 6

Why are rock records incomplete?

Answer 6

various weathering things such as erosion cause rocks to move locations, leaving some areas without rocks that would have originally been there.

Question 7

Body vs Trace fossils

Answer 7

Body fossils are fossils that preserve part of an organism’s actual body (bone, teeth, shell, feathers etc.) providing evidence on the organism’s actual structure. Preservation types include models, casts, carbon films, petrified, and preserved in something.

Trace fossils are fossils that provide indirect evidence of life (footprints, tracks, burrows, etc.) that reveal behavior or interactions of organisms. Preservation types include gastroliths, tracks, trails, and burrows.

Question 8

Molds and casts

Answer 8

Molds - when a shell is buried then dissolves, it leaves a mold
Casts - when sediments and minerals fill the open space below a shell

Question 9

Carbon film

Answer 9

organic matter in an organism is compressed and heated, leaving behind a thin residue of carbon

Question 10

Preservation fossils

Answer 10

when an organism completely is inside of something (sap from tree, ice, tar)

Question 11

Petrified fossils

Answer 11

when organic materials is replaced with minerals, turning it into a stone

Question 12

What environmental conditions favor fossil preservation?

Answer 12

Areas that are below freezing are good areas for fossils to be preserved in ice. Tar and amber also preserve fossils. Some bog environments that are low-oxygen and acidic can naturally mummify animals into fossils. Also, really hot areas can dry out organisms, also causing them to mummify.

Question 13

Four charactaristics of index fossils

Answer 13

Widespread around the Earth
Easily identifiable
From species that lived for a short time-span
Abundant

Question 14

Index fossil example and how they help uncover the past

Answer 14

Trilobites are an example of an index fossil because they only live for around 2 geological time periods, where others live much longer. They are also easy to identify. This can be used to provide critical information about the past because you can see what organism lives when based on where they are around the trilobite and also how long they lived.

Question 15

Principle of fossil succession

Answer 15

fossil organisms succeed one another in a definite and determinable order, and therefore, any time period can be recognized by its fossil content.

Question 15

Explain how the fossil record is a biased representation of past life on earth.

Answer 15

The fossil record is a biased representation of past life on Earth because some organisms (like ones with shells or living in certain environments) are more likely to be fossilized, whereas others could rarely be fossilized because they don’t have the right conditions.

Question 15

Theory of evolution

Answer 15

species adapt over time in response to their environment

Question 16

Natural selection

Answer 16

organisms that are more adapted to the environment are more likely to survive, others may die off.

Question 17

Explain how the Principle of Fossil Succession and the Theory of Evolution help scientists explain the fossil record.

Answer 17

The principle of fossil succession and the theory of evolution help scientists explain the fossil record because when you put the fossils in order, you can see slight changes which can form one organism adapting to its environment (evolution), confirming the fossil record order.

Question 18

Explain how fossils are used to date/correlate rock layers.

Answer 18

Fossils are used to date/correlate rock layers because if you know how old a fossil is, the rock layer that it is in must be very close in age, maybe a little bit older. You can also figure out which layers went on top of which by seeing how old the fossils that are in them are.

Question 19

Distinguish between relative age and absolute age dating.

Answer 19

Relative age dating tells you how old somehting is in general in relation to the things it is being compared to (which is older), however absolute dating tells you a very exact age of something.

Question 20

Rock Correlation

Answer 20

a method used to establish the relationship between rock layers at different locations. You identify and match specific rock layers or sequences of rock layers in different outcrops or drill cores based on their lithology, fossil content, or other characteristics.