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Join us in this oceanography class to delve into Earth's oceans, origins, and scientific methods. Learn about the interconnected global ocean, density stratification, and the formation of Earth's atmosphere and oceans. Discover the layers of Earth and its chemical and physical properties. Explore the age of Earth, geologic time scales, and the origins of life in oceans. Enhance your knowledge of Earth's internal structure and the processes that have shaped our planet. Expect engaging discussions and fascinating insights into our home planet!
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CHAPTER 1 Introduction to Planet “Earth”Instructor: C. Charles Dong
Personal Card Name E-mail • Classes taking this semester • Science/Math Background • Future Major/Career • Expectation of Class Expected Grade/Goal
Oceanography • Geological Oceanography • Chemical Oceanography • Physical Oceanography • Biological Oceanography
Outline • General Information: earth, oceans • Scientific Methods • Origin of Earth, Ocean, Atmosphere • Internal Structure of Earth
Overview • 70.8% Earth covered by ocean • Interconnected global or world ocean • Oceans contain 97.2% of surface water Fig. 1.3ab
The four principal oceans • Pacific • Atlantic • Indian • Arctic Plus: • Southern or Antarctic Ocean
Comparison of elevation and depth • Average depth 3729 m (12,234 ft) • Average elevation 840 m (2756 ft) • Deepest ocean Mariana Trench 11,022 m (36,161 ft) • Highest continental mountain Mt. Everest 8850 m (29,935 ft)
Exe. 01-01 • Name principle oceans on the earth. • Do you think if “earth” is misnamed for our planet? Why?
Scientific method • Observations • Hypotheses • Testing and modification of hypotheses • Theory • Probably true versus absolutely true • Science is continually developing because of new observations
Scientific method Fig. 1.9
Density is defined as: Mass of unit divided by Volume of unit = m / V Example: A rock has a mass of 5000 Kg Its volume is 2 m3 = m / V = 5000 Kg / 2 m3 = 2500 Kg/m3 Density
Density stratification • Protoearth experiences density stratification • Density = how heavy something is for its size • Density stratification causes high density material to sink while low density material rises • High density material = rock material and metals • Low density material = gases
Origin of the Solar System and Earth • Cloud of gas and space dust (nebula) began to contract about 4.6 billion years ago The Nebular Hypothesis
Origin of the Solar System and Earth • Protoplanets were created from the nebula • Protoearth was initially homogenous: • Larger in size than today’s Earth • Had lots of volcanic activity • No continents or oceans • No life
Origin of Earth’s atmosphere • Partial melting resulted in outgassing about 4 billion years ago • Similar to gases emitted from volcanoes • Mainly water vapor • Carbon dioxide, hydrogen • Other gases such as methane and ammonia
Origin of Earth’s oceans • Water vapor released by outgassing • Condensed as rain • Accumulated in ocean basins • About 4 billion years ago • Ice Comets were also important to adding water to the Earth system
Ocean salinity • Rain dissolves rocks • Dissolved compounds (ions) accumulate in ocean basins • Ocean salinity based on balance between input and output of ions • Ocean salinity nearly constant over past 4 billion years
Exe. 01-02 • Please describe how our solar system, the atmosphere and ocean were formed on the earth? • What is density stratification? • Why is sea water salty?
Earth’s internal structure • Highest density material at center (core) • Lowest density material at surface (crust) • Earth layered • Chemical composition • Physical properties
Chemical composition • Crust • Low-density, mainly silicate minerals • Mantle • Mainly Fe and Mg silicate minerals • Core • High-density, mainly Fe and Ni
Layered Earth Fig. 1.14
Physical properties • Lithosphere • Asthenosphere • Mesosphere • Outer core • Inner core
Physical properties • Lithosphere • Cool, rigid, brittle • Surface to about 100 km (62 miles) • Asthenosphere • Warm, plastic, able to flow • From 100 km to 700 km (430 miles)
Lithosphere • Oceanic crust • Underlies ocean basins • Igneous rock basalt • Average thickness 8 km (5 miles) • Relatively high density • 3.0 g/cm3
Lithosphere- Crust and Uppermost mantle fused together. • Continental crust • Underlies continents • Igneous rock granite • Average thickness 35 km (22 miles) • Lower density • 2.7 g/cm3
Asthenosphere • Upper mantle • Plastic—deforms by flowing • High viscosity—flows slowly
Exe. 01-03 • In terms of chemical property, how many layers does the earth have? List them. • In terms of physical property, how many layers does the earth have? List them.
Life in oceans • Earliest life forms fossilized bacteria in rocks about 3.5 billion years old • Marine rocks • Life originated in oceans?
Stanley Miller’s experiment • Organic molecules formed by ultraviolet light, electrical spark (lightning), and mixture of water, carbon dioxide, hydrogen, methane, and ammonia
Age of Earth • Radiometric age dating • Spontaneous change/decay • Half-life • Earth is about 4.6 billion years old
Geologic time scale Fig. 1.H
Exe. 01-04 • How old is the earth? When did life start on the earth? How do we know these?
Summary • General Information: earth, oceans • Scientific Methods • Origin of Earth, Ocean, Atmosphere • Internal Structure of Earth