Lecture 1 a THE OCEAN WORLD Chapter 1

Lecture 1 a: THE OCEAN WORLD Chapter 1

OCEAN FACTS • From Greek word Okeanos = outer sea • Body of salty water that occupies Earth’s depressions (below sea level) • 71% of Earth’s surface covered by ocean • 97% of the Earth’s total water • Covers 361 million square kilometers of Earth’s surface • Weighs 141 billion metric tons

OCEAN FACTS • Av. depth = 3. 8 km, average land elevation = 840 m • Depth tiny compared to distance to center of the earth • Av. temperature = 3. 9°C (39°F) • Av. salinity = 35 ppt (3. 5%) • 0. 02% of Earth’s mass • Most large cities on coast – 50% of humans live within 150 miles of the coastline

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THE 5 OCEANS Can be referred to as the world ocean

PACIFIC OCEAN • Largest ocean covering 30% of Earth’s surface • Av. depth 4. 3 km • Deepest part = Mariana Trench 10. 9 km • Volcanically very active www. eoearth. org

ATLANTIC OCEAN • 2 nd largest ocean • Covers 20% of Earth’s surface • S-shaped basin • Av. depth 3. 3 km • Second youngest ocean – 130 million years old • Getting larger! www. eoearth. org

INDIAN OCEAN • 3 rd largest ocean • Covers 14% of Earth’s surface • Av. depth 3. 9 km • Lies in tropics – warmest surface temperatures and very salty (32 -37 ppt) • Landlocked and open to Southern Ocean www. eoearth. org

SOUTHERN OCEAN • Below 60°S • 4% of Earth’s surface • 4 -5 km deep • Very strong ocean currents • Dangerous to navigate www. eoearth. org

ARCTIC OCEAN • Smallest ocean • Covers 3% of Earth’s surface • Av. depth 1 km (shallowest) • Nearly landlocked • Covered in ice www. eoearth. org

OCEAN VERSUS SEA • Seas are smaller and shallower • Saltwater composition • Enclosed by land • Connected to the ocean • e. g. Mediterranean, Caribbean

WHAT IS OCEANOGRAPHY? • The study of the ocean/marine environment • Marine Science

MARINE GEOLOGISTS/GEOLOGICAL OCEANOGRAPHERS • Composition of Earth • Seafloor sediments • Plate movement esp. earthquake prediction

PHYSICAL OCEANOGRAPHERS • Waves and currents • Ocean-atmosphere interactions • Predict long term climate change

MARINE BIOLOGISTS/BIOLOGICAL OCEANOGRAPHERS • Distribution and behavior of marine organisms • Pollution impacts • Fisheries

CHEMICAL OCEANOGRAPHERS • Dissolved solids and gases • Relationship to geology and biology • Aid in climate change predictions

OTHER RESEARCH AREAS Astronomy: - tidal forces - origin of life Geography: - weather and climate Engineering: - design and construction of structures used in or on ocean - oil platforms, harbors, shipyards Archaeology: - interactions between humans and the sea - shipwrecks, earthquake disasters

THE SCIENTIFIC METHOD Need to prove or disprove

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OCEAN EXPLORATION • Early civilizations voyaged for trade and exploration • Egyptians: – Library at Alexandria (founded 3 rd century B. C. ) stored information on explorations – Principle of celestial navigation – Circumference of the Earth, and system of longitude and latitude • Polynesia colonized thousands of years ago from Southeast Asia • China (1400’s) explored Indian and Atlantic Oceans

EUROPEAN EXPLORERS • Henry the Navigator – explored west coast of Africa • Christopher Columbus – never saw North American mainland, but his stories caused other explorers to follow • Ferdinand Magellan – died en route but remaining crew circumnavigated the globe

Fig. 1. 17 First voyage around the world, only 18 of the 260 sailors survived, took 3 years

VOYAGES AND SCIENCE James Cook (UK), British Royal Navy • HMS Endeavour (1768) – assert British presence in South Seas, greatly contributed to scientific oceanography – Verification of calculations of planetary orbits – Charting of New Zealand the Great Barrier Reef, Tonga and Easter Islands – Initiation of friendly relations with many native populations – Sampling marine life, land plants and animals – Recording data concerning the ocean floor and geological formations

• The United States Exploring Expedition launched in 1838 was a naval and scientific expedition. • The HMS Beagle, on which Charles Darwin served as a naturalist, voyaged to South America and some Pacific Islands. • (BELOW) HMS Challenger expedition of 1872 -1876 was the first oceanic expedition dedicated to scientific research. Fig. 1. 26

HMS CHALLENGER • 4 year voyage: – Life exists below 549 m (Azoic hypothesis), sampled down to 8000 m! – Discovered 4717 new species – Numerous salinity, temperature and density measurements – physical description of ocean – Ocean currents – Distribution of sediments – Location of coral reefs

OCEAN EXPLORATION IN THE 20 th CENTURY • Polar exploration – reached both the North and South Poles • Atlantis – confirmed presence of Mid-Atlantic Ridge • Trieste – a blimp-like bathyscaphe which descended into the Mariana Trench • Glomar Challenger - drilling ship, samples collected confirmed evidence for seafloor spreading

Echo sounders Deep sea drilling Submersible