geology 1003 old exam 2 | Luther lsu

True or False: Earth's atmosphere has changed very little since its formation.

false

True or False: Stanley Miller and Harold Urey's experiments showed that the amino acids required for life can be produced without available free oxygen.

true

By the end of the Proterozoic which of the following occurred?

all of the above

3 multiple choice options

How many episodes of Snowball Earth glaciation happened?

2, perhaps 3 (depending on what counts)

3 multiple choice options

Why are paleomagnetic records of low-latitude glaciation important?

If it was cold enough for glaciers at sea level at the equator, then it must have been cold enough for glaciers everywhere else on Earth.

3 multiple choice options

What rock type is evidence that significant portions of Earth's oceans were anoxic during the Snowball Earth glaciations?

banded iron formations

3 multiple choice options

During the Proterozoic Eon large amounts of carbonate rocks (limestone) formed and CO2 levels ___________, which would eventually lead to global _____________.

dropped, cooling

3 multiple choice options

True or False: Stable isotopes like O16/O18 help scientists determine past climate conditions.

true

What feature do we date to find the age of the Earth

Meteorites

3 multiple choice options

Which of these is a feature of a typical, modern plate boundary?

blueschist

3 multiple choice options

Which of these are possible feeding strategies for Archean-aged organisms?

Both Photosynthesis and Chemosynthesis

(only had bacteria/cyanobacteria)

3 multiple choice options

Which of the following statements is not true?

The Jack Hills zircon crystals originally crystallized in the Earth's first komatiite crust.

3 multiple choice options

Earth's first crust had the composition of which type of igneous rock?

Komatiite

3 multiple choice options

What is the next big milestone in Earth history after the melting of the last Snowball Earth glaciations?

The evolution of the first animals.

3 multiple choice options

During the process of differentiation, the _________________ elements migrated toward Earth's core while the __________________ elements rose toward Earth's surface?

Denser, Less dense

3 multiple choice options

The early Earth grew by adding space debris and planetesimals through the process known as?

Accretion

3 multiple choice options

What does the (a) presence of chert, limestone, and BIFs and (b) the absence of clastic sedimentary rocks imply about conditions during the Archean?

There was no land

3 multiple choice options

Are there any fossils in Archean sedimentary rocks?

Yes: microbially-induced sedimentary structures show microbial mats binding sedimentary grains together

2 multiple choice options

When were the "Snowball Earth" glaciations?

During the Neoproterozoic (near the end of the Proterozoic) era of geologic time

3 multiple choice options

Relative to a glacial deposit called a tillite, we might look for striations _________________ (see image above for an example).

below the tillite, on the unconformity surface separating it from the bedrock beneath

2 multiple choice options

The below diagrams depict examples of tiny phosphatized skeletons from the early Cambrian and represents "_____________".

small shelly fossils

3 multiple choice options

__Which of the following was not part of Gondwana?

British isles

3 multiple choice options

Why did animals develop hard parts?

To protect against predators

2 multiple choice options

Which of these time periods is the longest?

Precambrian

3 multiple choice options

define craton, shield, and platform

craton: old continental crust

shield: exposed craton

platform: craton covered by sedimentary rock

Describe the Ordovician Extinction

2 stages

1. global cooling: killed off tropical species

2. global warming: killed off species that adapted to cold weather

briefly discuss the difficulties that geologists face when study Archean life

- few fossils

- rocks deform, metamorphosed

What changes to life occurred during the Cambrian Explosion? Why was fossilization more successful than in the past?

-huge diversity of marine life, appearances of nearly every body plan, incease of predation

-many organisms have hard parts

What are the first vertebrates to move to land, how do these vertebrates change as they grow from eggs to adults, and what animal did they evolve from?

- Tetrapods (amphibians )

- Because theyre amp. They live in the water young and move to land as adults

- Evolved from the lobe finned fish

Describe one feature of plants that evolved in order for them to move to land. (Note 2025: We didn't talk specifically about this, so instead image, "Describe on feature of plants that evolved to allow them to grow taller and/or create soil")

-To grow taller -->developed root system,

- woody tissue to make them stronger

- leaf canopy increases planta ability for photosynthesis = more nutrients --> larger plant

- create soil by the root system

Define differentiation. Describe how density plays a role in differentiation. What are the major layers that formed during this process?

- Crust, mantle, core

- Most likely not on test

List two consequences of forests developing on land during the Middle Proterozoic.

Streamers affect root system

- Wide braided streams are replicated by meandering streams bc roots channels

Canopy --> water

- Leaf litter, inceases anoxia in swamp

What is the significance of banded iron formations?

Banded iron formations (BIFs) are significant because they provide crucial evidence of early Earth's oxygenation, serve as a primary source of iron ore, and offer insights into the planet's early geological history and the evolution of life.

Refer to the image below. At this stage, there is a lot of volcanism. How will this affect the climate? Will more or less limestone form? After this change in the amount of limestone production occurs, how will the climate change again?

- Co2 rises in atmosphere -> hotter

- More limestone -> warm climate = limestone

- When you make limestone you remove co2 from atmosphere meaning it'll get colder again

Briefly discuss how carbon in rocks vs. the atmosphere has an effect on the climate and the rock record.

- Carbon in rocks - low co2 in atmosphere meaning its colder

- Carbon in atmosphere - more co2 in atmosphere meaning its warmer

Briefly discuss the difficulties that geologists face when studying Archean life.

- Rare to find bc there aren't that many organisms and don't fossilize well

Briefly describe the three main types of types of organisms that made their debut in the Cambrian Period as recorded in the fossil record.

- Biomineralized fossils: small shelly fossils replaced by phosphorus

- Non-biomineralized fossils: haven't been replaced by another mineral -> e.g skeleton (still pure / hasn't disintegrated)

- Trace fossils: complex burrowing patters

What is the difference between a prokaryote and a eukaryote? Provide an example of each of these organisms present in the Precambrian.

Prokaryote: simple cells, ex: cyanobacteria

Eukaryote: complex cells, larger nuclei, Ex: human , grypania

Discuss the characteristics Ediacaran fauna and the evidence scientists used to determine these were animals.

- Forms at end of Proterozoic

- Mostly soft plants

- Thin to help with nutrient absorption

- First mobile creatures

- All marine

- No predators

How did burrows differ in the Precambrian and the Paleozoic?

In Precambrian they are horizontal, shallow, simple burrows,

In Pz: much more complex burrows, used for food, protection from predators, home

Why do scientists age date meteorites to determine the age of the Earth?

Because meteorites form at the same time as earth but earth surface was remelted several times due to major impacts in early earth