geosc 40 “the sea around us” rachel carson, 1951. book on environmental awareness. her writing...
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GEOSC 40
“The Sea Around Us”
Rachel Carson, 1951. Book on environmental awareness. Her writing reflects a passion and knowledge of the marine environment. She recognized research issues and foresaw environmental problems that are critical today.
Extra Credit Option bookreport / essay
Define OceanographyStudy of the ocean and its basins; a multidisciplinary science involving aspects of physics, chemistry, geology and biology.
Why are Oceans important to Man?Transportation
Defense
Recreation
Archeology
Fisheries
Minerals
Water Supply
Power Supply
Biomedicines
Global Climate
Natural Hazards
Pollutants
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BackPfiesteria piscicida toxins
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Hydrologic Cycle
Primary forces involved are solar radiation & gravity!
Solar energy drives evaporation and transpiration of land plants.
Gravity drives precipitation, infiltration and flow of streams and groundwater to oceans.
Atmospheric net transport is sea to land.
Define OceanographyStudy of the ocean and its basins; a multidisciplinary science involving aspects of physics, chemistry, geology and biology.
Where did Earth’s water originate? What is the origin of Earth?
Earth’s Ocean covers 71% of its surface area.
60.7:39.3sea:land
80.9:19.1sea:land
Origin of Earth and Life
• 15 billion Years Ago (15 Ga) the Big Bang to form the Universe.
• Simple atoms began to form during the following millions of years.
• After billions of years clusters of galaxies formed.
• Spheres of hot gasses (nebula) within galaxies ultimately formed individual solar systems.
Coma Berenices Galaxy 62 MLY away
Solar System Formation:Hot gasses of solar nebula begin the cool (5 Ga = 5 billion years ago) for our Sun.
Spinning sphere takes on a disk shape and heavy atoms coalesce into the center, forming a protosun.
Within the next 100 million years the accretion of atoms is so intense that nuclear fusion reaction begin, which form heavier elements, heat and light energy.
One day the Sun, like other past stars, will explode, or supernova.
Formation of Earth:4.7 Ga small asteroid, dust and gases in our solar system began to condense into planets.
Heavier materials were attracted closer to the sun than light gaseous materials. The plants close to the sun today (Mercury, Venus, Earth and Mar) are called terrestrial planets.
Jovian planets (Jupiter, Saturn, Uranus, Neptune, Pluto) are farther from the sun and made of the lighter gases compounds.
Materials that first aggregated to form the Earth, underwent the process called density stratification. Heavier elements went to the center and lighter stayed to the surface to form the cooler solid crust.
The Moon• Where did our moon come
from? – A collision >4.5 billion years
ago by either a– Huge asteroid, or – Mars size planet. – The material ejected from Earth
stayed in its gravitational field and aggregated.
• Why is the Moon important to life on Earth?– Tides – Gravity stabilizes the wobble of
Earth’s axis relative to the sun,– “If we had no Moon”.
Where did Earth’s water come from?
• 1) Outgassing of water from the Earth’s interior by volcanic activity. This alone could have filled the oceans in 0.5 billion years.
• 2) Bombardment by icy comets.
What may have been the Origin of Life on Earth?
Early Earth did not contain oxygen in its atmosphere, we refer the early atmosphere as reducing as opposed to oxidizing in its chemical nature.
One theory in the scientific community is that organic (carbon containing) compounds became more complex and organized until the first cells evolved from this “organic soup”. This is called the “Biosynthesis Theory”. Stanley Miller, 1953 apparatus
A second theory takes the biosynthesis idea further, and suggests that the processes needed to have protection from the violent (high UV) and cool surface, conditions. Deep-sea geothermal vents are proposed to be the location where life began.
The third theory, Panspermia, is that Earth may simply have been inoculated with life from an extraterrestrial source. There is evidence of meteorites with “life signs” and there are other planets or moons with water.
Compromise theories too!
Surface of Mars, once believed to have water at its surface, now only underground.
Surface of Europa (moon of Jupiter)
Fossilized microbes; 3.8 Ga in oldest rocks.
Geological History
Consider Earth as a 46 year old person:
Birth = first microbes (Prokaryotes) 3.6 Ga
21 y = first oxygen producing microbes 2 Ga
28 y = first advanced cells (Eukaryotes)
36 y = first multi-celled animals
Last 25 days = first humans
Last minute = industrial revolution 1850s
Last second was 2.5 years ago.