Chapter 1 Intro

Lecture 1

how much does the ocean cover?

how much does the ocean cover?

70.8% of earth

Are there other planets with liquid H2O?

no, but Jupiter’s moon Europa has a spidery network of fluid filled cracks of liquid H2O beneath the icy surface.

What moons have liquid oceans?

Ganymede and Callisto (Jupiter’s) have oceans beneath the icy crust. Enceladus (Saturn’s moon has some).

How much of the planet is water?

97.2% of Earth’s surface is water

What role do oceans play?

stable environment, influence climate and weather. lungs of our planet (produce O2), political boundaries

what are the oceans?

Pacific, Atlantic, Indian, Antarctic

Pacific ocean

largest ocean, half of Earth’s ocean space, deepest, largest geographic feature, named in 1520 by Ferdinand Magellan in honor of fine weather paci=peace

Atlantic ocean

half size of pacific, shallower than it, separates old world and new world, named after atlas, one of titans of Greek mythology

Indian ocean

smaller than atlantic, same depth, primarily in S hemisphere.

Arctic ocean

7% size of pacific ocean. shallowest in world, permanent layer of sea ice few m thick. named after Arctic region, beneath N constellation Ursa major (big dipper).

Southern (Antarctic) ocean

circumnavigates Antarctica, is really parts of pacific, atlantic, and indian oceans which lie S of 50 degree latitude

what is sea vs ocean?

they are used interchangeably, but a sea is smaller and shallower than oceans. they are salt water, (caspian sea is large lake with high salinity). enclosed by land, sargasso sea is defined by surrounding ocean currents. they are connected to ocean

Ancent 7 seas

Adriatic, Mediterranean, Persian Gulf, Black, Caspian, Indian, Red

how deep is the average ocean?

3682 m (12, 080 feet)

how high is the average continental elevation?

840 m (2756 feet)

what is the deepest ocean trench

Mariana Trench at 11,022 m (36, 161 feet)

what is the highest continental mountain

Mt. Everest at 8850 m (29, 035 feet)

Pacific navigators

no human evolution on Pacific islands. major island groups are Polynesia, Melanesia, Micronesia, nesia-island

when does archeological evidence suggest island occupation?

4000-5000 BC. Thor Heyerdahl sailed on a balsa raft the Kon Tiki to demonstrate migration of S Americans to Pacific Ocean islands

Phoenecians

first from W. Hemisphere to develop navigation arts around 2000 BC. Explored Mediterranean Sea, Red sea, indian ocean. First circumnavigation of Africa. reached british isles.

Herodotus

produced inaccurate world map around 450 BC

Claudius Ptolemy

produced fairly accurate world map around 150 AD. included lines of latitude and longitude. Erroneously updated original circumference estimation.

Middle ages exploration

destruction of library of Alexandria in 642 AD. Arabs dominant navigators of Mediterranean sea. traded with E. Africa, India, SE Asia. learned to use Indian Ocean monsoon winds for travel

Vikings exploration in N. Atlantic Ocean

settled Iceland and Greenland in 9th and 10th centuries AD. Leif Eriksson designated part of E Canada Vinland (now Newfoundland) in 995 AD. settlements abandoned by 1450 AD because of climatic cooling

Age of discovery

1492-1522

Who is Captain James Cook

undertook 3 scientific voyages: Endeavour, Resolution, Adventure. mapped pacific islands, measured ocean characteristics, marine chronograph (longitude)

What is oceanography?

scientific study of all aspects of marine environment

geological oceanography

studies sea floor structure, features, and the change over time

chemical oceanography

studies chemical composition and properties of sea water, such as pollutants

physical oceanography

studies waves, tides, currents, ocean atmosphere relationship, and transmission of light and sound

biological oceanography

studies ocean life forms

scientific method

collect info, formulate hypothesis, test, formulate theory, repeatedly test

nebular hypothesis

all bodies in the solar system formed from nebula (cloud of gases and space dust mainly H and He)

how does the nebular hypothesis work

as the nebular matter that formed the sun contracted, a small percent was left behind in eddies, flattened into disks, became gravitationally unstable, and broke into smaller clouds called protoplanets

protoplanets

small concentrations of matter formed by eddies

proto earth

atm. was largely H and He, larger than current earth, homogeneous composition, tons of meteorites. Moon formed from collision with large asteroid

how did the atm. form

sun became condensed and hot, core initiated process of thermonuclear fusion. cooling and contracting in size, radioactive heat deep in core, protoearth partially melted due to bombardment and heat by radioactivity, and density stratification

density stratification

result of gravitational forces in layering materials as a function of density. Iron and nickel settled to core, less dense formed concentric spheres

how are layers defined

chemical composition, physical properties

chemical composition of layers

crust: low density, silicate materials. mantle: mainly iron and magnesium. Core: high density, mainly iron, and nickel

layers by physical properties

lithosphere, asthenosphere, mesosphere, outer core, inner core

lithosphere

cool, rigid shell, includes crust and upper mantle, 60 miles thick (100km), brittle (when force applied, it fractures

asthenosphere

hot, plastic, high viscosity, important for movement of lithospheric plates, base of lithosphere 100 km to 700 km (430 miles) deep. partially melt portions of most rocks

oceanic crust

basalt (dark igneous rock), 3.0 g/cm cubed, 5 miles thick

continental crust

granite (light colored igneous rock) 2.7 g/cm cubed, 22 miles thick.

isostatic adjustment

The movement of the solid part of the earth until it is in balance. vertical movement of earth’s crust,

isostatic rebound

rising of crust formerly weighed down by glacier ice

outgassing

the process in which a non-metallic material such as a polymer, adhesive, rubber, or potting compound / epoxy will release a gas when exposed to heat and or a vacuum

formation of oceans

outgassed water fell as rain, permanent oceans formed 4 bya. Salinity developed from dissolved rock elements. Early acidic rain dissolved more crustal minerals.

earliest life forms

3.5 billion year old bacteria fossilized in ocean rocks. Basic building blocks of early life

oxygen importance

21% of atm, humans require o2 to burn (oxidize) food to release energy. ozone protects from UV.

Early oxygen

little free oxygen on early earth, helped originate life. atm oxygen was produced by photosynthetic activity or outgassing from mantle 2.5 bya.

stanley miller’s experiment

lab experiment in 1952 showed organic molecules came from inorganic. organic made up of CHNO.

how were organic molecules formed

uv light, electrical spark, h2o, co2, h, methane, and ammonia. “Primordial soup”

were heterotrophs or autotrophs first

heterotrophs, they required external food supply. autotrophs evolved later, as well as chemosynthesis. this supports the idea that life originated on the deep ocean floor without light

great oxidation event

2.45 bya the earth’s atm became oxygen rich. increased o2 and ozone eliminated anaerobic bacteria’s food supply of organic molecules and killed them. cyanobacteria adapted and thrived

age of earth

earth is 4.6 billion years old which we know due to radiometric dating