Geologic History of the Earth

[kingwinner]

I was working on my test review multiple choice questions in my textbook and encountered some that I am not sure about the answer. I hope someone can help me so I won't be studying the wrong answers!

 

Choose the best answer:

 

1) The geologic time scale is a

a. scale for weighing rocks

b. calendar used by geologist

c. rock record of the earth's past

d. collection of the same kind of rocks

I would eliminate a and d, but I am not sure if the correct answer is b or c...

 

2) An event that geologists would use in dividing the geologic time scale into smaller units is

a. the eruption of a volcano

b. a change in rock color

c. a change in sediment type

d. the arrival of an ice age

I really have no idea...

 

3) An important invertebrate in the Paleozoic Era was the

a. ammonite

b. trilobite

c. ostracoderm

d. stromatolite

Is the answer b?

===============================

4) Areas of exposed Precambrian rocks that may represent ancient continents are called

a. shields

b. fossils

c. outcrops

d. cratons

Is the answer a? or d?

 

5) During the Mesozoic Era, new crust was added to western North America in the form of

a. shields

b. terranes

c. cratons

d. geosynclines

This one I have no idea...

 

6) The Colorado Plateau was uplifted during

a. Precambrian time

b. the Paleozoic Era

c. the Mesozoic Era

d. the Cenozoic Era

Is the answer d?

 

Thank you for your help!

[Eclogite]

1) The geologic time scale is a

a. scale for weighing rocks

b. calendar used by geologist

c. rock record of the earth's past

d. collection of the same kind of rocks

I would eliminate a and d, but I am not sure if the correct answer is b or c...

Which is more associated with time, calendar or record?

 

2) An event that geologists would use in dividing the geologic time scale into smaller units is

a. the eruption of a volcano

b. a change in rock color

c. a change in sediment type

d. the arrival of an ice age

I really have no idea...

I am not surprised. This is a poorly phrased question. I would say, all of the above.

A volcanic eruption will spread lava or ash that is (a) very distinctive (;) can be dated © is often widespread (especially the ash)

A change in rock colour may indicate a change in environment. On the down side it may be a change in postdepositional environment and so be a poor indicator of time zones.

The change in sediment type can be helpful. Many of the major divisions of the geologic time scale are based upon this.

An ice age, with its attendant glacial deposits, can be an excellent dividing point.

3) An important invertebrate in the Paleozoic Era was the

a. ammonite

b. trilobite

c. ostracoderm

d. stromatolite

Is the answer b?

Another badly phrased question. Ammonites are found from the Silurian (Lower Paleozoic) up to the Mezozoic. Trilobites are mainly Lower Paleozoic. Ostracoderms are vertebrates, so they can be discounted. Stromatolites were mainly important in the Pre-Cambrian, but they persisted into the Paleozoic.

So, I would say a) and ;), but if I had to choose one, I would go with :) as you did.

4) Areas of exposed Precambrian rocks that may represent ancient continents are called

a. shields

b. fossils

c. outcrops

d. cratons

Is the answer a? or d?

I understand your confusion. Another, in my opinion, badly phrased question. I would opt for craton. A shield is a form of craton in which the ancient rocks are exposed at the surface. In other cratons they may be buried under newer sediments.

 

5) During the Mesozoic Era, new crust was added to western North America in the form of

a. shields

b. terranes

c. cratons

d. geosynclines

This one I have no idea...

!

Yes you do. Are shields old crust or new crust? Are terranes old crust or new crust? Are cratons old crust or new crust? See where we are heading?

 

6) The Colorado Plateau was uplifted during

a. Precambrian time

b. the Paleozoic Era

c. the Mesozoic Era

d. the Cenozoic Era

Is the answer d?

I have no idea. My educated guess would be d): it looks new. All that deep eorsion is geologically recent. I haven't ever studied North American geology. Use google to check. Let me know what you find.

[kingwinner]

Posted by mistake...see the next reply

[kingwinner]

Thanks for your help! :)

 

4) Areas of exposed Precambrian rocks that may represent ancient continents are called

a. shields

b. fossils

c. outcrops

d. cratons

 

It says areas of "exposed" Precambrian rocks.......

Then, would the answer be a? (since if cratons are exposed, they are called shields)

 

5) During the Mesozoic Era, new crust was added to western North America in the form of

a. shields

b. terranes

c. cratons

d. geosynclines

I would guess b, but is d also possible?

 

2) An event that geologists would use in dividing the geologic time scale into smaller units is

a. the eruption of a volcano

b. a change in rock color

c. a change in sediment type

d. the arrival of an ice age

We are to chose only 1 answer, which (a,b,c,d) do you think would be the best answer?

[Eclogite]

Sorry, I missed the 'exposed'. That would definitely be 'shields'.

 

Terrane is a term that was not in use when I studied geology. I would have leant towards (d), but in checking wikipedia for a discussion of terranes I read this:

The concept of terranes developed from studies in the 1970s of the complicated Western or Canadian Cordilleran ("backbone") orogenic margin of North America, virtually a geological lasagna that had remained an inexplicable irreducible complexity, until the new science of plate tectonics illuminated the ability of crustal fragments to "drift" thousands of miles from their origin and fetch up, crumpled, against an exotic shore. Such terranes are dubbed accreted terranes by geologists.

 

My perception had been that terranes were craton fragments. While they may be such, clearly in terms of the question they are adding 'new crust to North America'. It's just that the new crust is old crust! Again, I can't help but find fault with the structure of the question.

 

I could make an impassioned and eloquent argument (with detailed examples) for each of the four divisors of geologic ages. If I have to chose one I shall go for Ice Age - it does include a time term after all.

[kingwinner]

3) Stromatolite is a bacteria=>an animal

 

And all animals, including bacteria, are fall into either vertebrates or invertebrates, right? From my knowledge, a bacteria is not a vertebrate, so Stromatolite is an invertebrate, therefore a possible answer to question 3 under the context of "invertebrate". Because if Stromatolite is a vertebrate, I can eliminate this answer right away...since 3) An important invertebrate in the Paleozoic Era was the...

 

I don't know a lot about biology...

[Eclogite]

Bacteria are not strictly animals. Stromatolites are the fossil remains of cyano-bacteria. For a couple of billion years they dominated life on the Earth. So they are neither vertebrates or invertebrates, since they are not animals. So you can eliminate them.

[MortenS]

3) Stromatolite is a bacteria=>an animal

 

And all animals, including bacteria, are fall into either vertebrates or invertebrates, right? From my knowledge, a bacteria is not a vertebrate, so Stromatolite is an invertebrate, therefore a possible answer to question 3 under the context of "invertebrate". Because if Stromatolite is a vertebrate, I can eliminate this answer right away...since 3) An important invertebrate in the Paleozoic Era was the...

 

I don't know a lot about biology...

 

It is a long time since everything was classfied into plants and animals.

Some years ago, the five-kingdom classification scheme was common, but this is increasingly being replaced with a three-domain classification scheme.

 

5 kingdom classification: 
Kingdom Monera (procaryotic organisms: Archaebacteria and Eubacteria)
Kingdom Protista (single celled eukaryotic organisms)
Kingdom Animalia 
Kingdom Fungi
Kingdom Plantae

3-domain classification 

Domain Arcaea
Domain Bacteria
Domain Eukarya
    Kingdom Protista
    Kingdom Fungi
    Kingdom Animalia
    Kingdom Plantae
    

Invertebrates are everything within Animalia that is not vertebrates.

Bacteria is thus neither vertebrates nor invertebrates.

[LOC]

If I were to answer, I'd choose:

 

2. Ice Ages. Because the other options are better for distinguishing formations and members. I do agree the question is poorly phrased.

 

3. Ammonite. It's an important index fossil, if I remember correctly.

 

4. Shields.

 

5. Terranes. Accreted terranes are important to the geologic history of North America and not only for the western U.S., but also for everything south of Wyoming.

 

6. Cenozoic. The Plateau was uplifted during the Tertiary sometime between 3 and 6 million years ago, though a more precise date may be available.

[kingwinner]

Which is more associated with time, calendar or record?

1) To tell you the truth, they are both related to time in my opinion...:) I am really not sure about the answer...the answers b and c both make perfect sense to me...

[kingwinner]

I don't know why my replies are keep getting repeated, I just clicked edit and save

[Eclogite]

1) To tell you the truth, they are both related to time in my opinion...:hihi: I am really not sure about the answer...the answers b and c both make perfect sense to me...

Calendars contain days, months and years - all aspects of time.

Records contain........., well just about anything.

[kingwinner]

Calendars contain days, months and years - all aspects of time.

Records contain........., well just about anything.

But the geologic time scale recrods and sequent a number of events based on the rock record.........

[Boerseun]

Aaaaaaahhh...

 

...you gotta love geology...

 

(remember your hardhat)

 

:hihi: :hihi: :hihi: :shrug: :shrug: :evil: :lol: ;) ;)

[LOC]

After doing a little more digging around, the important fossil in the Paleozoic IS the trilobite (although it seems that the graptolite was even more important than the trilobite). Ammonites are most important in the Mesozoic.