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Chapter 2 The Dynamic Earth. Lesson 1 The Earth Forms. Earth travels at about 107,000km per hour Earth contains everything it needs to keep people alive A Life Support System. The Solid Earth. Not always welcoming to life Earth first formed Gas & rocky debris circling sun crashed together
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Lesson 1The Earth Forms • Earth travels at about 107,000km per hour • Earth contains everything it needs to keep people alive • A Life Support System
The Solid Earth • Not always welcoming to life • Earth first formed • Gas & rocky debris circling sun crashed together • 4.6B years ago • Energy heated Earth to high temperatures • Surface of earth was moltenor liquid rock
Major Layers of Earth • Earth eventually began to cool • Molten surface hardened to solid rock • Interior (core) kept some of the original heat
Major Layers of Earth • Crust – surface layer of rock & soil • Continental crust • Oceanic crust • Mantle – rock layer below the crust, surrounds the core; can soften • Core – round hot center
Gases & Liquids • Earth continued to cool • Gases escaped from millions of volcanoes and vents • Formed a layer of air around the earth • Gases cooled and some formed the oceans
Gases & Liquids • Earth still not inhabitable • Volcanic eruptions from beneath the earth’s surface were violent • Air was toxic, or poisonous to life • Rocky meteorites & icy comets battered Earth’s surface • Suns’ rays were damaging and dangerous
The First Life on Earth • Life finally appeared on the Earth in the oceans. • Tiny, single-celled living things that resembled bacteria • Some of these organisms could exist without oxygen • Feeding on chemicals in the environment • Using hydrogen to make their own food
The First Life on Earth Similar organisms……today • Similar bacteria-like organisms exist today • Known as Extremophiles • Thrive in the harshest environments A view of a hydrothermal vent (top photo). The super-heated black water pouring from the vent provides high-energy chemicals that sustain the tubeworms (bottom photo) and other organisms that thrive in this unlikely habitat. Credit: Woods Hole Oceanographic Institution
Kingdom Archaebacteria • Methanogens • Harvest energy by converting H2 and CO2 into methane gas. • Anaerobic; found at bottom of swamps & intestinal tracts of humans and cows • Extreme halophiles • “Salt-loving” bacteria; live in high salt concentrations • Use salt to generate ATP • Found in Great Salt Lake & the Dead Sea • Thermoacidophiles • Found in extremely acidic with high temperatures • Temperatures up to 230°F and pH < 2 • Found in hot springs Yellowstone National Park, near volcanic (land) or hydrothermal (ocean floor) vents
Cyanobacteria • About 2 -2.7M years ago; First bacteria • Blue-green algae formed in shallow seas • Produced own food using energy from the sun • Released oxygen as a waste product • Toxic gases: Methane/ammonia Oxygen • Earth was now ready to support many different forms of life
Cyanobacteria • First organisms on Earth to use sunlight to make their own food; aka blue-green algae.
Lesson 2Land, Water and Air Earth’s Life Support System Three Major Parts • Lithosphere • Solid surface & interior (moving) • Hydrosphere • Liquid layer; Earth’s water • Atmosphere • Layer of air surrounding Earth • Life can be found in all 3 layers • Collectively known as Earth’s Biosphere
The Lithosphere • Earth’s solid and interior surface • Consists of: crust, mantle and core • Surface cracked; and began moving • Theory is called Plate Tectonics • Explains theory of Continental Drift, how continents move over time. • Today, Earth contains: • 12 major plates • Hundreds of smaller ones.
Plate Tectonics • One of the most important theories in geology • Alfred Wegener, a German scientist • Proposed a hypothesis in 1915 • Suggested that all continents had once been joined as one and broke apart to drift to their current locations • The Origin of Continents and Oceans, pub 1915. • Named this movement continental drift. • By 1960, other scientists added to his ideas.
Plate Tectonics • Movement of Earth’s plates created today’s land features. • Mountains formed when plates bump into each other and push upward • Plates slide past one another they catch and create tension • Tension is released in the form of an earthquake • Volcanoes form along the edges of plates where plates move apart or collide
Plate Tectonics • Plate movement created Earth’s continents • Plates are not continents • Plates carry both continental & oceanic crust • Ex. NA + Atlantic Ocean part of NA Plate • Ex. Hawaii, Alaska, CA & Pacific ocean = Pacific Plate • Plate movement also responsible for tsunamis
Plate Tectonics • Called Pangaea (from the Greek for "all the Earth")
The Hydrosphere • The hydrosphere is the liquid water component of the Earth. It includes theoceans, seas, lakes, ponds, rivers and streams. The hydrosphere covers about 70% of the surface of the Earth and is the home for many plants and animals.
The Hydrosphere • The hydrosphere, like the atmosphere, is always in motion. • The characteristics of the ocean which affects its motion are its temperature and salinity. • Warm water is less dense; moves up toward the surface • Colder water is more dense; sinks towards the bottom. • Salty water is also more dense and thus tends to sink • Fresh or less salty water is less dense or lighter and thus tends to rise toward the surface.
Earth’s Oceans (97% of Hydrosphere) • The ocean serves two main purposes in the climate system. • First, it is a large reservoir of chemicals that can contribute to the greenhouse effect in the atmosphere and energy absorbing 90% of the solar radiation which hits the surface. This reservoir changes very slowly limiting how fast the climate can change. • Second, it works with the atmosphere to redistribute the energy received from the sun such that the heat in the tropics, where a lot of energy is received from the sun, is transferred toward the poles, where heat is generally lost to space.
The Atmosphere • Air that surrounds Earth; contains a mixture of gases -- Mostly nitrogen & oxygen • Made up of 4 Layers • Troposphere (0-16km); where weather occurs • Stratosphere (16-50km); contains ozone layer • Mesosphere (50-80km) • Thermosphere (80-480km) • Farther away from Earth: Colder & thinner
Ecosystem Recycling Energy flows through an ecosystem one way Water & Minerals are recycled and reused
Lesson 3Cycles of Life • All matter cycles...it is neither created nor destroyed... As the Earth is essentially a closed system with respect to matter, we can say that …. all matter on Earth cycles .
Cycles of Matter • Energy is crucial to an ecosystem • All organisms need more than energy to survive. • They also need water, minerals and other life-sustaining compounds. • Although common on Earth, organisms can’t use them unless they are in a chemical from that they can take up and process.
Cycles of Matter • Unlike the one-way flow of Energy, Matter is recycled within and between ecosystems. • Elements, chemical compounds and other forms of matter are passed from one organism to another and from one part of the biosphere to the next through biogeochemical cycles.
Cycles of Matter • Matter can cycle through biosphere because biological systems do not use up matter, they transform it. • The Law of Conservation of Matter
The Hydrological (Water) Cycle • Most of earth’s water is stored in the oceans, but solar energy continually evaporates this water, and winds distribute water vapor around the globe. • For billions of year, there has been the same amount of water on Earth • Less than 1% can be used for drinking
Water • Water is crucial to life • Makes up 70-90% of cells • Provides the aqueous environment for most of life’s chemical reactions. • Key factor that regulates the productivity of terrestrial ecosystems. • Very little is trapped within living things.
The Water Cycle Evaporation Transpiration Condensation Precipitation Runoff Seepage Root Uptake
The Carbon Cycle • Photosynthesis and cellular respiration form the basis of the carbon cycle. • Decomposers release CO2 into atmosphere • break down organic compounds. • CO2 Levels Rising • Last 150 yrs, risen almost 30%; 50% in last 40yrs. • Human activities responsible for the increase: • Burning of fossil fuels and vegetation • Destruction of vegetation (rainforest)
The Nitrogen Cycle • All organisms need nitrogen to make proteins and nucleic acids. • Nitrogen gas makes up about 78% of the atmosphere. • Most plants can use nitrogen only in the form of nitrate. • Organisms rely on bacteria that convert gas into useable form. • Nitrogen Fixation - process of converting nitrogen gas to nitrate. • Nitrogen-fixing bacteria - convert nitrogen gas into ammonia nitrite nitrate which plants can use. • Bacteria live in soil and in the roots of legumes • Mutualistic relationship
The Nitrogen CycleRecycling Nitrogen • Ammonification – the process by which decomposers break down the corpses and wastes of organisms and release the nitrogen they contain as ammonia. • Nitrification – bacteria in the soil take up ammonia and oxidize it into nitrites (NO-2) and nitrates (NO-3) • Denitrification –anaerobic bacteria breakdown nitrates and release nitrogen gas back into atmosphere.
Phosphorus Cycle • Helps living things grow & develop • Abundant phosphorus stimulates plant and algal productivity. • One of the main elements found in bones & teeth • Found in rocks, bottom of shallow oceans • Absorbed from the soil by plants, passed on to animals and returned to soil via animal waste.
Sulfur Cycle • Sulfur compounds are important determinants of the acidity of water. • Particulates may also act as critical regulators of global climate. • Sulfur cycle is complicated by a large number of possible oxidation states.
Lesson 4Climate and Weather • Life on earth is inextricably linked to climate through a variety of interacting cycles and feedback loops. In recent years there has been a growing awareness of the extent to which human activities, such as deforestation and fossil fuel burning, have directly or indirectly modified the biogeochemical and physical processes involved in determining the earth's climate.
Weather vs. Climate • Weather • Moment by moment conditions of the atmosphere • Climate • The long-term average of weather conditions in a particular place.
Where does weather come from? • Several things coming together • Sun • Air • Water (especially Oceans) • Solid Earth
Sun • Plays the largest role in weather production • Warms the ground, air & water • Drives • Temperature changes • The water cycle • Air movement • Does not strike all parts of the world equally
Sun • What part of the earth receives the most direct sunlight? • The Equator (imaginary line that circles the Earth halfway between the North & South poles) • Why is the sunlight at the poles weaker? • Because it comes at an angle; Earth is tilted • Reason why the tropics (near the equator) are warmer than the poles.
Amount of Sunlight • Depends upon the time of day and the time of year. • Northern Hemisphere tilts toward sun • Spring/Summer - North of the equator (Canada, Europe) • Winter-Southern Hemisphere (Australia)
Air on the Move • Air moves in response to temperature differences • Air circulates around the globe in a regular pattern • Sunlight at the equator creates warm air masses • Atoms move faster & air expands • Warm air is less dense; rises and moves toward poles • At poles air cools and sinks back down toward the equator • As the Earth spins it causes the winds to turn. • Known as the Coriolis effect
The Coriolis Effect • Results in 3 major patterns of global air, known as prevailing winds • Trade winds • Prevailing westerlies • Polar easterlies
The Coriolis Effect • Prevailing winds do not cause every wind; some form because of local temperatures as well • Ex.) Differences in temp between a cold ocean and warmer land creates sea breezes. • Huge temperature differences in the atmosphere create jet streams, which are powerful rivers of air that can cause big changes in the weather.
