Formation of the Earth

Question 1

Pangea

Answer 1

• Supercontinent that consisted of all present landmasses before they broke up and drifted to present positions
• Alfred Waegner – early 1900’s
• Continental drift theory and Pangaea theory
• questioned and doubted
• confirmed in 1968 with Glomar Challenger trip
• drilled holes in seafloor, examining sediment samples and fossil records

Question 2

Formation of the Earth

Answer 2

• Earth formed 4.6 billion years ago
• Gas and dust came together to form clumps which we now call earth
• Pressure compressed layers and heated inside
• Volcanos poked through, sent gases into atmosphere
• Water vapors condensed, fell as rain, bringing chemicals to it, creating seawater
• -> First Life in the ocean
• Organic compounds in a “soup” combined through lightning to form bacteria
• photosynthetic bacterial cells produced O2
• -> O2 supported more complex life forms as bacteria eventually evolved into sponges and corals

Question 3

Ancient Seas

Answer 3

• Panthalassa
• Major ocean surrounding Pangaea
• Tethys Sea
• -> Ancient smaller marine body
• -> Now covered by the Mediterranean Sea, the Indian Ocean, and parts of Indonesia, Iraq, and Turkey

Question 4

The Word Ocean

Answer 4

• Greek word “okeanos” = river
• greeks believed the ocean was one great river flowing around earth
• Covers 60% of northern hemisphere
• Covers 80% of Southern hemisphere
• Covers 70% of the earth
• Earths water: 98% seawater, 1.8% ice caps/glaciers, 0.2% lakes/rivers
• Average depth is 3800m
• 1/2 population lives within 200 miles of coastline
• 1/3 of oil comes from below seafloor
• provides 2% of worlds direct food

Question 5

Structure of the Earth and Ocean

Answer 5

• Earth’s crust is made of plates that float on a mantle
• As magma bubbles up, plates move and carry continents with them
• African continent is moving north, closing off the Mediterranean Sea
• Atlantic Ocean is widening at 3 cm/year and the Pacific Ocean is getting smaller at 4 cm/year

Question 6

Mid Ocean Ridge (MOR)

Answer 6

• Chain of underwater volcanic mountains
• Ex: Mid Atlantic Ridge
• Ex: East Pacific Rise
• Sea floor rock gets older the further away you move from the MOR
• Molten rock bubbles up thru rift
• New sea floor is created and spreads away from MOR
• Presence of hydrothermal vents and black smokers

Question 7

Trenches

Answer 7

• Spot where 2 plates of earth collide and 1 dips under the other back into the earth (subduction)
• Mariana Trench in Australia (36,000), Puerto Rico Trench in Atlantic (28,000 feet)

Question 8

Life on a MOR

Answer 8

• Iceland; island country located on a section of the mid-atlantic ridge
  Benefits:
• springs supply hot water for irrigation of crops in summer
• steam generates electricity for every home
• Hot water to swim in
• Steam powered greenhouses with fresh veggies
  Downside:
• Frequent earthquakes
• Highly active volcanos

Question 9

Features of the ocean

Answer 9

Continental shelf:

• smooth with gentle slope (2 degrees)
• 0-600 feet deep
• 8% of total area of ocean
• provides 80-90% of world’s seafood
• ends at shelf break

Continental slope:

• boundary between continental masses and the true ocean basin
• 600-10,000 feet deep
• Very steep (25 degrees)

Continental rise:

• build-up of sediment at base of continental slope
• narrow, ranging up to 62 miles in width
• steeper than the shelf, average angle of 4 degrees

Abyssal plain:

• 10,000-36,000ft deep
• Flat, featureless and sediment covered
• Some life; small in size - big eyes to absorb light
• Covers 50% of earth