Unit 2 Flashcards
Cenozoic Era
- The Cenozoic Era, spanning 65 million years, is Earth’s third documented era.
- The era marked the shift of continents, creating vast oceans and influencing climate and marine life.
- The Pleistocene Epoch saw glaciers covering central North America, leading to the formation of the Great Lakes.
- The Cenozoic Era also marked the extinction of giant mammals, allowing smaller species to thrive.
- The period saw the emergence of early primates, including early humans, and the emergence of various species.
- Plant life flourished during this period, with nearly every plant having roots in the Cenozoic Era.
- The era also saw the proliferation of marine life, including the formation of the Great Lakes in southern Canada.
- As forests thinned, grasses spread over North America, and savannas covered the land in the middle of the continent.
Mesozoic Era
- The Mesozoic Era, also known as the age of reptiles, spanned from 252 million years ago to 66 million years ago.
- Divided into three time periods: the Triassic, the Jurassic, and the Cretaceous.
- The Earth was much warmer during this period, with no polar ice caps and equatorial oceans too warm to support sea life.
- The period saw the breakup of Pangaea into seven continents, with North America breaking away from Africa’s northwest coast.
- The era saw a flourishing diversity of animals, including massive lizards and iconic dinosaurs.
- Most fossils found in Alberta date back to the Mesozoic period.
- Lush plant life emerged during this era, providing food for dinosaurs growing up to 100 tons.
Paleozoic Era
- Period from 542 million years ago to 251 million years ago.
- Breakup of one supercontinent and formation of another.
- Widespread spread of plants and first tetrapods colonizing land.
- Life flourished in the seas, with first land animal development.
- Plants evolved on land without leaves.
- Coral reefs provided shelter for fish and shelled creatures.
- Many continents broke apart and formed new ones.
- Volcanic activity decreased to normal levels.
- Atmosphere changed to support life.
- Sea levels rose, causing shallow seas in North America.
- Appalachian Mountains on east coast of Canada formed.
- By end of Era, Pangaea formed.
Precambrian
- The Precambrian period, spanning about seven-eighths of Earth’s history, spanned from the first formation of the planet (4.6 billion years ago) to 570 million years ago.
- Between 4 billion and 2.5 billion years ago, continental shield rock began to form, forming about 70% of continental landmass.
- By 2.5 billion years ago, enough shield rock had formed to initiate geologic processes like plate tectonics.
- Water from comets and hydrated minerals condensed in the atmosphere, cooling the planet and filling the first oceans with liquid water.
- Life began in the oceans about 3.5 billion to 2.8 billion years ago.
- The earliest living organisms were microscopic bacteria, appearing as early as 3.4 billion years ago.
- The first multi-celled animals, known as the Ediacarans, appeared around 600 million years ago, resembling modern life-forms.
What are the 6 main parts the earth is made out of
The atmosphere
The crust
The Asthenosphere
The mantle
The outer core
The inner core
The Atmosphere
Allows for life on the planet Earth.
Contains 78% nitrogen and 21% oxygen
Contains 5 layers:
Exosphere, Lonosphere, Mesosphere, Stratosphere (contains the ozone layer), and Troposphere (where weather occurs)
The crust
The outermost portion of the Earth
The crust floats on the Asthenosphere and are broken up into continental plates
The Oceanic crust is thinner than the continental crust.
The Mantle
The Asthenosphere
The “upper” mantle. This liquid rock is what the crust of the Earth rests on. This allows the solid crust of the earth to “float” on the earth.
Lower Mantle
A thick layer of molten rock. Heat travels through this current which moves the rock. These are called convection currents.
Is 84% of the Earth’s volume.
The Outer Core
A liquid layer that surrounds the Inner
Core of the Earth.
Is made up of Nickel and Iron, same materials as the Inner
Core
Over time layers of the outer core cools and are added to the Inner Core. 1mm per year added
The Inner Core
A solid ball made of Iron and Nickel.
It is 70% the size of the moon
Radiates heat to the upper layers of the earth
Who is Alfred Wegener
1915 a man named Alfred Wegener came up with the theory of continental drift
Believed all the continents are in constant motion and collide into one another
Scientists did not believe him because he did not explain what forces made the continents
move
Continental Drift theory
What where Wegeners 4 pieces of evidence
- Coastlines
The edges of continents looked like they could fit together - Fossils
Fossils of the same animal exists across continents. This means the
continents needed to be connected for the animals to travel across - Mountains
There are mountains similar in age and structure on both sides of the Atlantic. This means they must have been formed together at one point in time - Glaciers
The Ice sheets covered parts of southern Africa, India, Australia and South
Africa about 250 million years ago. This means they must have been connected
Tuzo Wilson
- In 1960, Wilson expanded Wegener’s theories.
- By 1968, plate tectonics emerged.
- Theory posits Earth’s crust is divided into tectonic plates.
- Plates move due to mantle convection currents.
- Constant pressure causes mountains, trenches, and earthquakes.
Convergent Boundary
When Tectonic plates collide, the older heavier plate slides under the newer
lighter plate. This process is called Subduction. The lighter plate gets pushed into the sky creating mountains
Divergent Boundary
Plates moving away from each other. This creates Mid-Ocean Ridges. Small mountain ranges stretching along the ridge under the water.
Transform Boundary
When two plates move adjacent to each other. This area is prone to many earthquakes but does not necessarily create
mountain ranges
What is a hot spot
Third Way, Mountains/Volcanoes Form
Weak spot on the Earth’s Crust. Allows magma to push through and form mountains. Usually occurs under the ocean where the Plates are thinner
what causes earthquakes
Earthquakes are the result of sudden movement along faults within the Earth. The movement releases stored-up ‘elastic strain’ energy in the form of seismic waves, which propagate through the Earth and cause the ground surface to shake.
What is the Pacific Rim of Fire
The area around the Pacific Plate that contains 75% of the world’s volcanoes
90% of earthquakes and 81% of the world largest Earthquakes occur here
What causes volcanic activity
Deep within the Earth it is so hot that some rocks slowly melt and become a thick flowing substance called magma. Since it is lighter than the solid rock around it, magma rises and collects in magma chambers. Eventually, some of the magma pushes through vents and fissures to the Earth’s surface.
Indigenous rock
Igneous rock, a type of rock formed from molten magma, forms the crust of Earth, which is thin and resembles the skin of a balloon. This igneous rock, such as granite, basalt, and obsidian, is formed when the crust cracks open, causing earthquakes and lava eruptions.
