1.2 C: Geology = the Changing Earth 1.2 Early Life Flashcards
What is Cameron Falls known for?
A popular sightseeing spot in Waterton Lakes National Park featuring ancient sedimentary rock
Cameron Falls is located in southwestern Alberta.
What type of rock is highlighted at Cameron Falls?
Alberta’s oldest sedimentary rock
The rock shows layers of sediment compressed into solid rock.
What do the properties of sediments and fossils in sedimentary rock reveal? In Canada around when were these deposited?
Evidence about the type of environment that existed when they were deposited 1.5 billion years ago.
Where did the sediments that formed the layers at Cameron Falls likely originate?
At the mouth of a river flowing into an ancient ocean.
What do similar Precambrian sedimentary rock formations indicate?
That several large rivers deposited sand, clay, and silt into an ancient ocean.
What is sedimentary rock?
Rock formed from compressed layers of pre-existing rock or organic matter.
Define ‘fossil’.
The evidence or remains of ancient life preserved in Earth’s crust.
What are ‘strata’?
The layered bands within sedimentary rock.
Fill in the blank: A sandwich of sedimentary rock at Cameron Falls is currently _______ km thick.
1
What was the early Earth environment like?
Hostile with frequent volcanic eruptions, poisonous gases, and extremely hot oceans over 100°C
The atmosphere contained little oxygen.
What did scientists initially believe about life in extreme conditions?
Life under extreme conditions would have been impossible
This belief was based on the harsh environment of early Earth.
What recent discoveries have changed the perception of life in extreme conditions?
Discovery of a group of extreme bacteria-like organisms that tolerate heat and live on poisonous gases
These organisms are known as Archaea.
Where was one of the first discoveries of Archaea made?
In the boiling waters of hot springs in Yellowstone National Park
This discovery indicated that life can thrive in extreme environments.
At what temperature were similar creatures found near deep-sea thermal vents?
150°C
This highlights the adaptability of life in extreme heat.
Fill in the blank: The oceans on early Earth were extremely _______.
hot
More than 100°C.
True or False: The early Earth’s atmosphere had a high concentration of oxygen.
False
The atmosphere contained little oxygen.
What gases were prevalent in the early Earth’s atmosphere?
Methane and hydrogen sulfide
These gases contributed to the hostile conditions.
What is the world’s oldest evidence of life?
3.8 billion years ago
This evidence includes fossilized remains that suggest life existed during this time.
What type of organisms are considered the earliest life forms?
Single-celled bacteria
These organisms are believed to have appeared approximately 3.8 billion years ago.
What is a stromatolite?
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.
What are cyanobacteria?
Microscopic, photosynthetic, single-celled bacteria
Cyanobacteria are significant for their role in producing oxygen and contributing to the Earth’s atmosphere.
Fill in the blank: Life may have existed before _______ years ago, but there is no fossil evidence to support this.
3.8 billion
True or False: There is a consensus in the scientific community about how and when life began on Earth.
False
There is still plenty of debate among scientists regarding the origins of life.
What are deep-sea thermal vents?
Locations that release intense volcanic heat and hydrogen sulfide gas
Which organisms thrive near deep-sea thermal vents?
Archaea organisms
What gas do Archaea feed on near thermal vents?
Hydrogen sulfide
True or False: Hydrogen sulfide is safe for humans.
False
What may Archaea organisms represent in terms of Earth’s history?
The closest living relatives of Earth’s earliest life
How long ago did the layers of rock at Cameron Falls start to form?
15 billion years ago
What type of environment surrounded Cameron Falls during its formation?
A large shallow mud flat
What type of fossil evidence indicates the presence of cyanobacteria?
Stromatolites
Where did cyanobacteria live in ancient times?
In the tropically warm shallow waters along the coast of ancient landmasses
Fill in the blank: The organisms living near deep-sea thermal vents are known as _______.
Archaea
What are cyanobacteria?
Microscopic, photosynthetic single-celled bacteria
They are among Earth’s first photosynthetic organisms.
How do cyanobacteria contribute to the formation of limestone?
By growing and dying one layer on top of the other, depositing layers of calcium carbonate
Calcium carbonate is the main ingredient of limestone and our bones.
What are stromatolites?
Large mounds formed by layers of calcium carbonate from cyanobacteria
Stromatolites can be 10 to 30 cm tall and are remnants of ancient cyanobacterial activity.
What type of fossil are stromatolites an example of?
Trace fossil
They are not the actual cyanobacteria but represent evidence of their existence.
What impact does the atmosphere have on the evolution of life?
It affects the evolution of future life and has spinoff effects on the planet’s geology
This relationship is explored in investigations regarding Earth’s oxygen-rich atmosphere.
Fill in the blank: Stromatolites are the remains of _______.
calcium carbonate layers
True or False: Cyanobacteria are multicellular organisms.
False
Cyanobacteria are single-celled organisms.
What geological phenomena will the next investigation explore?
The impact of Earth’s oxygen-rich atmosphere
This will include its effects on geological processes.
What does the presence of banded iron formations indicate about Earth’s early atmosphere?
It suggests the presence of oxygen in Earth’s atmosphere during the Precambrian Era
What role did cyanobacteria play in making Earth livable?
Cyanobacteria were one of the only early producers of oxygen
They significantly contributed to the development of an oxygen-rich atmosphere, essential for other forms of life.
Where is the earliest direct evidence of cyanobacteria found?
Isua Rock in Greenland
This evidence dates back 3.7 billion years.
What complex molecule did cyanobacteria use to trap the Sun’s energy?
Chlorophyll
Chlorophyll is essential for photosynthesis, allowing organisms to convert sunlight into energy.
What process uses the Sun’s energy to make glucose from carbon dioxide and water?
Photosynthesis
This process is crucial for the production of energy in plants and cyanobacteria.
What is the by-product of photosynthesis?
Oxygen
Oxygen is released into the atmosphere as a result of the photosynthesis process.
For how long were cyanobacteria the dominant form of life on Earth?
Two billion years
Despite their microscopic size, they had a significant impact on Earth’s atmosphere and ecosystems.
How did cyanobacteria impact Earth’s atmosphere?
They are largely responsible for creating Earth’s atmospheric oxygen
This transformation was critical for the evolution of aerobic life forms.
True or False: Cyanobacteria were the first organisms to use chlorophyll.
True
This adaptation allowed them to harness solar energy for photosynthesis.
What significant ice age is referred to as ‘Snowball Earth’?
A time period late in the Precambrian Era when icecaps covered most of the planet for nearly ten million years
What happened to the oceans during ‘Snowball Earth’?
The oceans froze solid except for small pockets of water that remained liquid due to heat escaping from Earth’s mantle
What evidence of glacial activity is found in late Precambrian rocks?
Evidence of glaciers advancing and retreating
Where can evidence of Precambrian glacial activity be found?
In rocks all over the world, including Alberta’s Rocky Mountains
What do some scientists believe was the result of the stresses placed on organisms during the deep freeze of ‘Snowball Earth’?
An explosion in species diversity leading to the first complex creatures
By the end of the Precambrian Era, what percentage of Earth’s history had passed?
Nearly 90%
What were the first producers that transformed the atmosphere?
Cyanobacteria
What indirect evidence of cyanobacteria’s existence is found in the geological record?
Stromatolite mounds and banded iron deposits
What direct evidence of early life is found in the Rocky Mountains?
Fossil imprints
What types of features shared the shallow waters with stromatolites?
Multicellular creatures like small jellyfish, worm-shaped animals, and ferns
What major section of geological time was initiated by an explosion of new and bizarre creatures?
The Paleozoic Era
Fill in the blank: The first producers, ________, transformed the atmosphere.
cyanobacteria
