1.2 C: Geology = the Changing Earth 1.2 Early Life

Question 1

What is Cameron Falls known for?

Answer 1

A popular sightseeing spot in Waterton Lakes National Park featuring ancient sedimentary rock

Cameron Falls is located in southwestern Alberta.

Question 2

What type of rock is highlighted at Cameron Falls?

Answer 2

Alberta’s oldest sedimentary rock

The rock shows layers of sediment compressed into solid rock.

Question 3

What do the properties of sediments and fossils in sedimentary rock reveal? In Canada around when were these deposited?

Answer 3

Evidence about the type of environment that existed when they were deposited 1.5 billion years ago.

Question 4

Where did the sediments that formed the layers at Cameron Falls likely originate?

Answer 4

At the mouth of a river flowing into an ancient ocean.

Question 5

What do similar Precambrian sedimentary rock formations indicate?

Answer 5

That several large rivers deposited sand, clay, and silt into an ancient ocean.

Question 6

What is sedimentary rock?

Answer 6

Rock formed from compressed layers of pre-existing rock or organic matter.

Question 7

Define ‘fossil’.

Answer 7

The evidence or remains of ancient life preserved in Earth’s crust.

Question 8

What are ‘strata’?

Answer 8

The layered bands within sedimentary rock.

Question 9

Fill in the blank: A sandwich of sedimentary rock at Cameron Falls is currently _______ km thick.

Answer 9

1

Question 10

What was the early Earth environment like?

Answer 10

Hostile with frequent volcanic eruptions, poisonous gases, and extremely hot oceans over 100°C

The atmosphere contained little oxygen.

Question 11

What did scientists initially believe about life in extreme conditions?

Answer 11

Life under extreme conditions would have been impossible

This belief was based on the harsh environment of early Earth.

Question 12

What recent discoveries have changed the perception of life in extreme conditions?

Answer 12

Discovery of a group of extreme bacteria-like organisms that tolerate heat and live on poisonous gases

These organisms are known as Archaea.

Question 13

Where was one of the first discoveries of Archaea made?

Answer 13

In the boiling waters of hot springs in Yellowstone National Park

This discovery indicated that life can thrive in extreme environments.

Question 14

At what temperature were similar creatures found near deep-sea thermal vents?

Answer 14

150°C

This highlights the adaptability of life in extreme heat.

Question 15

Fill in the blank: The oceans on early Earth were extremely _______.

Answer 15

hot

More than 100°C.

Question 16

True or False: The early Earth’s atmosphere had a high concentration of oxygen.

Answer 16

False

The atmosphere contained little oxygen.

Question 17

What gases were prevalent in the early Earth’s atmosphere?

Answer 17

Methane and hydrogen sulfide

These gases contributed to the hostile conditions.

Question 18

What is the world’s oldest evidence of life?

Answer 18

3.8 billion years ago

This evidence includes fossilized remains that suggest life existed during this time.

Question 19

What type of organisms are considered the earliest life forms?

Answer 19

Single-celled bacteria

These organisms are believed to have appeared approximately 3.8 billion years ago.

Question 20

What is a stromatolite?

Answer 20

A layered structure formed by microbial mats

Stromatolites are often associated with ancient microbial life.

a calcareous mound built up of layers of lime-secreting cyanobacteria and trapped sediment, found in Precambrian rocks as the earliest known fossils, and still being formed in lagoons in Australasia.

Question 21

What are cyanobacteria?

Answer 21

Microscopic, photosynthetic, single-celled bacteria

Cyanobacteria are significant for their role in producing oxygen and contributing to the Earth’s atmosphere.

Question 22

Fill in the blank: Life may have existed before _______ years ago, but there is no fossil evidence to support this.

Answer 22

3.8 billion

Question 23

True or False: There is a consensus in the scientific community about how and when life began on Earth.

Answer 23

False

There is still plenty of debate among scientists regarding the origins of life.

Question 24

What are deep-sea thermal vents?

Answer 24

Locations that release intense volcanic heat and hydrogen sulfide gas

Question 25

Which organisms thrive near deep-sea thermal vents?

Answer 25

Archaea organisms

Question 26

What gas do Archaea feed on near thermal vents?

Answer 26

Hydrogen sulfide

Question 27

True or False: Hydrogen sulfide is safe for humans.

Answer 27

False

Question 28

What may Archaea organisms represent in terms of Earth's history?

Answer 28

The closest living relatives of Earth's earliest life

Question 29

How long ago did the layers of rock at Cameron Falls start to form?

Answer 29

15 billion years ago

Question 30

What type of environment surrounded Cameron Falls during its formation?

Answer 30

A large shallow mud flat

Question 31

What type of fossil evidence indicates the presence of cyanobacteria?

Answer 31

Stromatolites

Question 32

Where did cyanobacteria live in ancient times?

Answer 32

In the tropically warm shallow waters along the coast of ancient landmasses

Question 33

Fill in the blank: The organisms living near deep-sea thermal vents are known as _______.

Answer 33

Archaea

Question 34

What are cyanobacteria?

Answer 34

Microscopic, photosynthetic single-celled bacteria ## Footnote They are among Earth's first photosynthetic organisms.

Question 35

How do cyanobacteria contribute to the formation of limestone?

Answer 35

By growing and dying one layer on top of the other, depositing layers of calcium carbonate ## Footnote Calcium carbonate is the main ingredient of limestone and our bones.

Question 36

What are stromatolites?

Answer 36

Large mounds formed by layers of calcium carbonate from cyanobacteria ## Footnote Stromatolites can be 10 to 30 cm tall and are remnants of ancient cyanobacterial activity.

Question 37

What type of fossil are stromatolites an example of?

Answer 37

Trace fossil ## Footnote They are not the actual cyanobacteria but represent evidence of their existence.

Question 38

What impact does the atmosphere have on the evolution of life?

Answer 38

It affects the evolution of future life and has spinoff effects on the planet's geology ## Footnote This relationship is explored in investigations regarding Earth's oxygen-rich atmosphere.

Question 39

Fill in the blank: Stromatolites are the remains of _______.

Answer 39

calcium carbonate layers

Question 40

True or False: Cyanobacteria are multicellular organisms.

Answer 40

False ## Footnote Cyanobacteria are single-celled organisms.

Question 41

What geological phenomena will the next investigation explore?

Answer 41

The impact of Earth's oxygen-rich atmosphere ## Footnote This will include its effects on geological processes.

Question 42

What does the presence of banded iron formations indicate about Earth's early atmosphere?

Answer 42

It suggests the presence of oxygen in Earth's atmosphere during the Precambrian Era

Question 43

What role did cyanobacteria play in making Earth livable?

Answer 43

Cyanobacteria were one of the only early producers of oxygen ## Footnote They significantly contributed to the development of an oxygen-rich atmosphere, essential for other forms of life.

Question 44

Where is the earliest direct evidence of cyanobacteria found?

Answer 44

Isua Rock in Greenland ## Footnote This evidence dates back 3.7 billion years.

Question 45

What complex molecule did cyanobacteria use to trap the Sun's energy?

Answer 45

Chlorophyll ## Footnote Chlorophyll is essential for photosynthesis, allowing organisms to convert sunlight into energy.

Question 46

What process uses the Sun's energy to make glucose from carbon dioxide and water?

Answer 46

Photosynthesis ## Footnote This process is crucial for the production of energy in plants and cyanobacteria.

Question 47

What is the by-product of photosynthesis?

Answer 47

Oxygen ## Footnote Oxygen is released into the atmosphere as a result of the photosynthesis process.

Question 48

For how long were cyanobacteria the dominant form of life on Earth?

Answer 48

Two billion years ## Footnote Despite their microscopic size, they had a significant impact on Earth's atmosphere and ecosystems.

Question 49

How did cyanobacteria impact Earth's atmosphere?

Answer 49

They are largely responsible for creating Earth's atmospheric oxygen ## Footnote This transformation was critical for the evolution of aerobic life forms.

Question 50

True or False: Cyanobacteria were the first organisms to use chlorophyll.

Answer 50

True ## Footnote This adaptation allowed them to harness solar energy for photosynthesis.

Question 51

What significant ice age is referred to as 'Snowball Earth'?

Answer 51

A time period late in the Precambrian Era when icecaps covered most of the planet for nearly ten million years

Question 52

What happened to the oceans during 'Snowball Earth'?

Answer 52

The oceans froze solid except for small pockets of water that remained liquid due to heat escaping from Earth's mantle

Question 53

What evidence of glacial activity is found in late Precambrian rocks?

Answer 53

Evidence of glaciers advancing and retreating

Question 54

Where can evidence of Precambrian glacial activity be found?

Answer 54

In rocks all over the world, including Alberta's Rocky Mountains

Question 55

What do some scientists believe was the result of the stresses placed on organisms during the deep freeze of 'Snowball Earth'?

Answer 55

An explosion in species diversity leading to the first complex creatures

Question 56

By the end of the Precambrian Era, what percentage of Earth's history had passed?

Answer 56

Nearly 90%

Question 57

What were the first producers that transformed the atmosphere?

Answer 57

Cyanobacteria

Question 58

What indirect evidence of cyanobacteria's existence is found in the geological record?

Answer 58

Stromatolite mounds and banded iron deposits

Question 59

What direct evidence of early life is found in the Rocky Mountains?

Answer 59

Fossil imprints

Question 60

What types of features shared the shallow waters with stromatolites?

Answer 60

Multicellular creatures like small jellyfish, worm-shaped animals, and ferns

Question 61

What major section of geological time was initiated by an explosion of new and bizarre creatures?

Answer 61

The Paleozoic Era

Question 62

Fill in the blank: The first producers, ________, transformed the atmosphere.

Answer 62

cyanobacteria