EARTH SPACE SCIENCE - SCIHP2

Natural selection 

✘Natural selection is the process through which populations of living organisms adapt and change over time. 

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✘Individuals in a population are naturally variable, meaning that they are all different in some ways. 

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✘This variation means that some individuals have traits better suited to the environment than others.

Adaptation

Special features an organism has that assists them in surviving in their environment.

The result of the genes the organism inherited from its parents.

Can be naturally selected for as they increase chance of survival.

The 3 Types of Adaptations 

✘We classify adaptations in 3 ways-

✗Physical appearance (Structural)

✗Internal systems (Physiological)

✗Something an organism does (Behavioural)

Structural adaptations 

A structural adaptation is a body part  or physical feature that helps an organism to survive.

Example- a bat has wings for flying.

Physiological adaptations

A physiological adaptation is a feature of the way an organism’s body functions. 

They are innate, meaning they are not learnt by the organism.

Eg. When you exercise, your body automatically makes your heart beat faster so that more blood is supplied to your muscles.

Behavioural adaptations 

A behavioural adaptation is a feature of an organism’s habits, actions or way of life that helps it to survive.

Example- a desert mouse only coming out at night when the air has cooled.

The four spheres

Our earth is divided into 4 interacting systems

-Atmosphere

-Biosphere

-Hydrosphere

-Geosphere

Geosphere

Part of the earth that is made up of rocks and minerals. It starts at the ground and extends all the way down to Earth’s core.

Hydrosphere

the hydrosphere encompasses all liquid, solid (ice), and gaseous water existing on, under, and above the Earth's surface, continuously cycled through the water cycle.

Atmosphere

The atmosphere is the invisible blanket of gases that surrounds Earth, essential for life and climate.

Biosphere

The biosphere is the global sum of all living organisms and their interactions with air, water, and land.

The geosphere of our earth is divided into:

7 sections

The Crust

The crust ranges between 5-70km in depth- this is VERY thin compared to other layers.

Continental crust: 

a layer of solid rock and minerals which forms continents and tectonic plates. 

Less dense than oceanic crust.

Oceanic crust: 

extends 5-10km
beneath the ocean floor. 

Very dense.

The Mantle 

The mantle is about 2,900km thick in total

It makes up 84% of earths volume!

Lithosphere

Solid outer part of the earth - includes the
crust and the upper part of the mantle

From surface to 100km down.

Solid

Asthenosphere

Denser, weaker, and semi-molten layer

From 100km down to about 400km down

Semi-solid

Mesosphere (lower mantle)

From about 400km down to 2900km down

Semi-solid

The Core 

The core is the very dense and hot center of our planet.

Starts at about 2,900km down and goes to its center at about 3,485km down.

Made mostly of iron and nickel.

Outer core

2,200km thick

Temperature ranges between 4,500^oC and 5,500^oC

Liquid

Inner core

1,220km in radius

Temperature range from 5,000^oC to 6,000^oC 

In a plasma state of matter but behaves as a solid 

Continental Drift

220 million years ago (mya) 

only one continent, mainly in the southern hemisphere. 

Called Pangaea.

200 mya 

Pangaea breaks apart 

due to movement of tectonic plates. 

Formed two land masses: 

Laurasia: drifted north, 

Gondwanaland: drifted south.

Continental Drift (150 mya)

(90 AAAISA NEA)

150 mya: Gondwanaland separates into Africa, Antarctica, Australia, India and South America.

60 mya: Laurasia separates into North America ,Europe and Asia.

Continents continued to move, to where they are today.

Why does continental drift occur?

This all occurs due to the movement of tectonic plates, causing what is called, continental drift.

Tectonic means “Building” so tectonic plates are the building plates of earth.

Earth has 7 major tectonic plates

What causes tectonic plate movement?

While the actual cause of tectonic plate movement is not fully understood, it is believed their movement is due to convection currents.

Theory of continental drift:"

In 1915 Alfred Wegener a German scientist proposed that the continents were slowly drifting apart

This is the theory of continental drift

Matching coastlines

Wegener noticed that the coastlines of Africa and South America looked like they fit together.

Other continents also looked like they fit together

Fossil evidence

Fossils of the same plants and animals are found today on widely separated continents

Glacial evidence

There are evidence of glaciers on parts of the earth that used to be on the equator, and tropical rainforests on parts of the earth now located in the arctic.

Paleomagnetism 

Revealed magnetic striping on the ocean floor, confirming that continents had drifted as the Earth magnetic field reversed overtime 

Sea floor spreading 

showed that new crust was forming at mid-ocean ridges proving continents could move apart as Wegener suggested 

Why do the tectonic plates move? 

The main theory is that the hot magma in the asthenosphere rises up and then flows horizontally along under the plates, creating convection currents. These currents then drag the plates above them along. 

Plate Boundaries 

There are 3 main types of tectonic plate boundaries:

Diverging boundaries- plates move apart from each other

Converging boundaries- plates collide with each other

Transform boundaries- plates slide past each other

Subduction 

When oceanic and continental crust collide, the denser oceanic plate subducts beneath the continental plate, forming a deep trench. As it sinks into the hot mantle, friction and heat melt the oceanic crust into magma, causing crust to be destroyed.

Density 

When two continental plates collide, both are pushed upwards because neither is denser than the other. This forms very high mountain systems.

The best-known example of this is where the Indian Plate is colliding with the Eurasian Plate. This has formed the highest mountain range on Earth, the Himalayas.

what is ecology?

Ecology is the study of how organisms interact with each other and with their environment.

To interact means to affect each other, in ways that may assist or harm each other. 

The environment consists of all the factors in an organism’s surroundings that affect it.

Terminology - population ecology

We define a community as all the organisms that occupy a particular place at any particular time.

A population: 

is the members of the same species that occupies a particular place at any particular time. 

Can be measured in terms of abundance – how many individuals there are in total and density – the number of individuals per unit area.

Ecosystems 

An ecosystem is a system formed by a group of living things interacting with each other and their non-living surroundings.

Ecosystems have 3 main components:

Physical surroundings (rocks, soil, water)

Living organisms 

Living and nonliving factors that make up the environment 

Biotic & Abiotic Factors  

Biotic factors are the living factors in the environment. E.g. prey, predators.

Abiotic factors are the non-living/ physical factors in the environment. (e.g. water, air quality, the amount of light, temperature, wind, soil type, humidity of the air, tides, waves, lightning and fires.)

Water 

Water is essential for the chemical reactions in the cells of living things. 

All organisms require water, though not all need to drink it. Some obtain enough water in their food 

Temperature (Endothermic + Ectothermic)

As it increases, this increases the rate of chemical reaction in our cells.

Can influence the life cycles of plants and animals. 

Plants start to grow and bloom when it gets warmer.

Can affect animal hibernation or migration.

Ectothermic animals (whose body temperatures vary with the environment)

Endothermic (generate their own heat and control their heat loss).

Biotic Factors (skip)

Organisms rarely live alone

The living things in an ecosystem form a community. 

The living things in a community have different relationships with each other, they all interact differently.

This is what we will be looking at today 

5 main biotic factors 

1.Competition

2.Predation

3.Mutualism

4.Parasitism

5.Commensalism 

Competition 

If organisms are both trying to obtain the same limited resources, they are said to be in competition.

Competition can occur between members of the same species, and between members of different species.

Predation 

When one organism kills and eats another, the attacker is called the predator and the one being eaten is called the prey. 

This feeding relationship is known as predation. 

Symbiosis (skip)

The next 3 biotic factors are also known as types of symbiosis

Symbiosis is the close and long term interaction of organisms

As we are about to see- sometimes this has benefits, other times it is detrimental/harmful.

Mutualism

Mutualism is a relationship where two organisms live closely together and both benefit.

Parasitism 

Parasitism is a relationship where one organism lives on or in another organism (the host) and feeds off it. 

The parasite cannot survive without the organism in which it lives.

The parasite usually harms the host, but rarely kills it.

Commensalism 

Commensalism is a relationship where one organism benefits and the other is unaffected.

The Ring of Fire

The Ring of Fire is a region around much of the rim of the Pacific Ocean where many volcanic eruptions and earthquakes occur. 

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•The Ring of Fire is a horseshoe-shaped belt about 40,000 km long and up to about 500 km wide.

The Ring of Fire – Plate tectonics 

•The Ring of Fire is a direct result of plate tectonics: specifically, the movement, collision and destruction of lithospheric plates under and around the Pacific Ocean.

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•The collisions have created a nearly continuous series of subduction zones, where volcanoes are created, and earthquakes occur. 

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•Consumption of oceanic lithosphere at these convergent plate boundaries has formed ocean trenches, volcanic island arcs and volcanic belts. 

The Ring of Fire - Volcanoes 

The Ring of Fire contains approximately 850–1,000 volcanoes that have been active during the last 11,700 years (about two-thirds of the world's total).

The Ring of Fire – Earthquakes 

•About 76% of the Earth's seismic energy is released as earthquakes in the Ring of Fire.

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•About 90% of the Earth’s total earthquakes and about 81% of the world's largest earthquakes occur along the Ring of Fire.

How are volcanoes formed?

Volcanoes form where molten rock (magma) from the mantle pushes upwards through weaknesses in the Earth’s surface. 

Magma that reaches the surface is known as lava.

Volcano structure

Stratovolcano

Shape:

• Stratovolcano: Tall, symmetric peak with steep slopes.

  How it is formed:

  • Stratovolcano: Built from alternating layers of viscous lava flows, ash, pumice, and bombs.

    Locations:

    • Stratovolcano: Subduction zones (Andes, Japan, Cascades, Philippines).

Explosions:

• Stratovolcano: Highly explosive due to viscous magma trapping gases; pyroclastic flows, ash columns.

Shield Volcano

Shape: Shield volcano: Broad, gently sloping sides; wide, flattened profile.

How it is formed: Shield volcano: Low-viscosity magma (basalt) creates long lava flows that build a broad shield.

Locations: Shield volcano: Mid-ocean ridges and hotspots (Hawaii, Iceland, Galápagos).

Explosions: Shield volcano: Generally less explosive; mainly effusive lava flows, occasional lava fountains.

Cinder cone

Shape: Cinder cone: Steep, conical hill with a narrow base

How it is formed: Eruptions eject tephra that fall around the vent, forming a small cone.

Locations: On the flanks of larger volcanoes or along rift zones (e.g., western US, Mexico, Chile/Argentina regions).

Explosions: Small-to-moderate explosive events; short-lived eruptions.

Examples:Parícutin (Mexico), Sunset Crater (USA), Cerro Negro (Nicaragua).

What is an earthquake? 

An earthquake is the rapid
movement of the ground
(usually in a wave motion). 

What causes an earthquake?

An earthquake is caused by the rapid release of energy as tectonic plates move. 

Epicenters and Foci 

•Earthquakes usually occur along a fault.

•The focus is the place where an earthquake starts. Usually many hundreds of kilometers deep in the Earth.

•The epicenter is the point on the Earth’s surface directly above the focus. 

Where do earthquakes occur? 

Earthquakes generally start at the edges of the tectonic plates.

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Earthquakes do not just happen at transverse boundaries but happen at all plate boundaries. 

Convergent
boundaries
(subduction zones)
create the strongest
earthquakes.

How do earthquakes occur in Australia? 

While most earthquakes occur along tectonic plate boundaries, a small number of earthquakes occur along faults (cracks) in the normally stable interior of plates.

Seismic Waves 

The movement of the ground in an earthquake occurs in a shaking back-and-forth motion called a wave.

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Three main types of seismic waves can be detected:

1.P-wave

2.S-wave

3.Surface Waves

Primary & Secondary Waves 

•Primary waves (P-waves) are longitudinal waves that travel fast through the Earth.

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•Secondary waves (S-waves) are transverse waves that travel slightly slower than P-waves through the Earth.

Surface Waves 

•Surface waves are the slowest waves and cause the most destruction.

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•Surface waves travel along the crust near the surface. 

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•They travel more slowly than P-waves and S-waves, but they can be much larger. 

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•They are particularly destructive if the earthquake is near the Earth’s surface.

Detecting earthquakes 

•Earthquakes are measured using a seismometer.

•The heavy mass attached to the pen stays in one place. The other parts move around it with the movements of the earthquake. 

•Produces a drawing (seismogram) displaying the movement caused by the earthquake.

Magnitude

Magnitude is the energy released by an Earthquake.

The strength, or magnitude, of an earthquake is measured using the Richter scale. 

Earthquakes can cause:

•Damage to buildings

•Landslides

•Tsunamis

•Liquefaction