wednesday november 9, 2011
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WednesdayNovember 9, 2011
(Origin of the Atmosphere and
Oceans )
The Launch PadWednesday, 11/9/11
Briefly describe the following components of Earth’s
structure:crustupper mantlelower mantleouter coreinner core
Brittle, oceanic & continental, thinSolid but mobile, asthenosphereSolid, hot, dense rocky materialLiquid, metallic, iron & nickel, creates magnetic fieldSolid metallic, iron & nickel, extremely
high pressure
Assignment Currently Open
Summative or Formative
Date Issued
Date Due
Date Into
Grade Speed
Last Day
Project – Moon Features F1 10/18 10/21
Quiz 8 S (last 6-wks) 10/26 10/26 10/27 11/10
Quiz 9 S (last 6-wks) 11/2 11/2 11/3 11/17
Video WS – Fearless Planet – Earth Story F2 11/3 11/10
Activity – Draw Earth’s Internal Structure
F3 11/8 11/9
AnnouncementsI will be available
today after school until 4:45 PM.
We may have a Quiz tomorrow.
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Figure 12.6Over 4 billions years ago volcanic activity
was producing Earth’s primitive atmosphere and
oceans.
Stromatolite bacteria mounds
Figure 12.7Earth’s primitive
atmosphere, which consisted mainly of H2O vapor and CO2,
was formed by a process called
“outgassing”, in which gases trapped
in the planet’s interior are released
by volcanic eruptions.
This process continues
today.
Origin of the Atmosphere and Oceans Water vapor
condensed to form
clouds and
rainwater that formed
the oceans.
Origin of the Atmosphere and Oceans
About 3.5 billion years ago,
photosynthesizing bacteria began
to release oxygen.
Origin of the Atmosphere and Oceans
Oxygen levels steadily increased
Origin of the Atmosphere and Oceans Eventually oxygen levels were sufficient for ozone to develop in the atmosphere.
These layered, iron-rich rocks, called banded
iron formations, were deposited during the
Precambrian. Much of the oxygen generated
as a by-product of photosynthesis was readily consumed by
chemical reaction with iron to produce these
rocks.
Origin of the Atmosphere and Oceans Outgassing produced acidic conditions
that caused an accelerated rate of weathering of Earth’s rocky surface.
Origin of the Atmosphere and Oceans
Products of this
weathering were
carried to the oceans,
thus increasing the salinity
of the oceans..
Origin of the Atmosphere and Oceans The oceans also served as a depository for carbon dioxide, which is readily soluble in
water.
CO2 reacts with other substances in seawater to form calcium carbonate (limestone.) Eventually, marine organisms would removed calcium carbonate from the seawater to make their shells. When these organisms died, their remains were deposited on the
seabed in the form of chalk. These chalk beds later became exposed, as in this picture of the White Cliffs of Dover, in southern England.
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