Transcript Earth & Ocean Formation

Beginnings
1. Earth’s formation
2. Earth’s timeline
Earth’s Formation
The Universe - formed 10-15 billion years ago
Currently referred to as the ‘Big Bang‘
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current theory is that the universe was formed from something
smaller than an atom
the atom exploded and everything was blown outward with great
heat and speed
Earth’s Formation
Our Solar System was formed 4.6 billion years ago
The Earth is assumed to be the same age
http://www.talkorigins.org/faqs/faq-age-of-earth.html
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At this time, Earth had a surface
~ known from radiometric dating of meteorites (uranium and potassium
We think water condensed on the planet 3.9 billion years ago
~ known from radiometric dating of sedimentary rocks that
formed by processes requiring water
Earth’s Formation
Where did oceans come from?
Old Theory:
a) H2O came from big comets during period of
heavy bombardment
a) H2O locked up in minerals released from
differentiation (cooling and melting of magma) and
heating processes
Earth’s Formation
Where did oceans come from?
(cont’d)
New Theory:
a) Oceans are still forming and H2O comes from many small
cometessimals that continually bombard the Earth
a) H2O came from big comets during period of heavy
bombardment
a) H2O locked up in minerals released from differentiation
and heating
Earth’s Timeline
Mother Earth formed 4.6 billion years ago..
What has happened during this time?
Earth’s Timeline
(cont’d)
Divide by 4.6 billion by 100 million years - makes Earth
46 years old
0-3 yrs
3 yrs
8-11 yrs
22-23 yrs
31 yrs
39th yr
41rst yr
no record
dated from rocks in Canada, Africa
and Greenland
1st living cells - primitive bacteria
oxygen production by cells begins
atmosphere has enough oxygen to
support life
first invertebrates-hard shelled fossils
primitive fish and corals
Earth’s Timeline
(cont’d)
41-42 yrs
43 yr
44 yr
45 yr
land plants, fish
reptiles, dinosaurs, sharks
dinosaurs dominate
dinosaurs die
1 yr ago
plants and flowers proliferate
7 mos. ago
25 days ago
6 days ago
1/2 hour ago
1 minute ago
insects, mammals, birds proliferate
first humans
homosapiens
1st recorded civilization
industrial revolution
 change Earth and relationship
with Earth for all time…
Earth
1. Coordinates
2. Earth’s Water
3. Earth’s Structure
Coordinates
Earth
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Highest mountain is Mt. Everest at 8840m above sea level
Lowest trench is the Mariana Trench (Pacific) at 11,000m
below sea level
Think of earth like a basketball - the
bumps would be the mountains and
the dimples would be the trenches.
Earth has a huge mass!!!
Coordinates
(cont’d)
Latitude and Longitude
Latitude
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Parallel to the equator
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Expressed as degrees N or S of the equator where equator = 0
Coordinates
(cont’d)
Latitude and Longitude
(cont’d)
Longitude
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Lines of longitude are meridians
Longitudinal lines are at a right angle to
latitudinal grid
0° longitude is known as the prime meridian
Goes right through Royal Observatory in
Greenwich, England
Greenwich Mean Time = ‘Universal Time’,
when sun is directly above 0 longitude
• Expressed as degrees E or W of prime meridian
where prime meridian = 0
Earth’s Water
How Earth's water reservoirs are connected
Connected by 2 processes:
evaporation and precipitation
See fig 1.18 (Intro 7e) or 2.13 (Fund. 4e)
Earth’s water reservoirs:
Oceans 97.2%
Lakes, rivers and inland seas 0.017%
Glaciers 2.14%
Atmosphere 0.001%
Ground H20 0.61%
Biosphere 0.005%
WORLDS WATER SOURCES:
Earth’s Structure
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Layered system (like an onion, concentric regions)
~ differentiation of mineral material
Not only Earth’s mineral
material, but also:
1. hydrosphere
2. biosphere
3. atmosphere
Earth’s Structure
(cont’d.)
Classification according to chemical composition
4 concentric regions of
mineral material:
1. crust
2. mantle
3. outer core - molten
4. inner core - solid
Earth’s Structure
(cont’d.)
Classification according to chemical composition
1. Crust
Two types:
continental g granite – composed of
silicates rich in Na, K & Al
ocean g basalt – composed of
silicates rich in Ca, Mg & Fe
• represents 0.4% of Earth’s mass
• extends down to 75 km
Earth’s Structure
(cont’d.)
Classification according to chemical composition
2. Mantle
Three parts:
uppermost/middle/innermost
• Composed of Mg-Fe silicates
• represents 68% of Earth’s mass
• extends down from base of
crust to ~2,900 km
Earth’s Structure
(cont’d.)
Classification according to chemical composition
3. Core
Two parts:
Outer
Inner
• Composed of Fe & Ni
• Represents 28% of Earth’s mass
• Extends down from base of
mantle ~ 6400km
Earth’s Structure
(cont’d.)
Classification according to physical properties
(factor in temperature and pressure)
4 concentric regions:
1. lithosphere - rigid outer shell (crust & uppermost mantle)
• 100 - 150km thick
• does not change shape
Earth’s Structure
(cont’d.)
2. Asthenosphere - soft, flows over geologic time under the weight of
the lithosphere (small fraction of middle mantle)
• lithosphere ‘floats on top’
• zone where magma formed
• 200 – 350km thick
• easily deformed, can be pushed down by overlying lithosphere –
“plastic” – tar or asphalt
Earth’s Structure
(cont’d.)
Classification according to physical properties
3. Mesosphere - rigid but not as hard as lithosphere
• higher temp than asthenosphere, but not molten because of
compression pressure
• 4950km thick
Earth’s Structure
(cont’d.)
Classification according to physical properties
4. Core - outer is molten, inner is solid
Earth’s Structure
(cont’d.)
Isostacy
Principle that dictates how different parts
of the lithosphere stand in relation to each
other in the vertical direction
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Continental crust less dense (granitic) therefore rises higher
relative to ocean crust (basaltic)
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Continents move up and down depending on weight on top (i.e.
from glaciers - ‘isostatic rebound’)
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Continents pop up after glaciers melt
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Canada and Scandinavia rising at a rate of 1m/100yrs
because the glaciers are receding
Earth’s Water
(cont’d.)
Five oceans:
1.
Atlantic – shallowest, greatest number of adjacent seasregional seas: i.e. Gulf of Mexico, Caribbean, Mediterranean,
North), has the largest freshwater input (i.e. Amazon, Congo,
Mississippi)
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Pacific – largest, deepest
3.
Indian – smallest, muddiest
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Arctic – covers N. Pole, saltiest
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Southern Ocean – coldest, most productive
(Some) OCEANS’ FACTS:
 Our planet is actually the Ocean Planet - 77% of the Earth’s surface is covered
by oceans and seas. However, less than 10% has been investigated.
 Oceans provide more than 70% of oxygen we breathe
 80% of world’s plant and animal species live in oceans
 More than 60% of the current human population (5.8 billion) lives in the coastal
zones (~60 km wide), the areas representing only 8% of the Earth surface!
 ‘Poorest of the poor’ - 1.1 billion people ‘survive’ on less than 1$/day
 1 billion people rely on fish as the only daily source of protein
 Global climate change and the humans’ well being depend on the conditions and
health of the oceans;
 Poverty, hunger, diseases as well as casualties from natural disasters can be
alleviated by improving the health of the environment and by sustainable use and
management of the coasts and oceans!