Exam 1 requirements

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Exam 1 requirements
GE 146 Plate tectonics Exam I (January 31)
requirements are posted on the course
website- http//www.geo.lsa.umich.edu/jritsema
Pages 1 through 14 of This Dynamic Earth
Section of 1.1 of "Historical Perspective" The
Scientific Method Geologic Time Pages 4-8 of
Chapter 1 entitled "Building a planet" from
"Understanding Earth See me after class if you
are missing copies of any of the hand-outs !!!
FINAL PAPER DUE April 18 instead of April 13
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Symposium on friday
Origins The Universe, Earth, and Life 110-630
pm, Modern Languages Building Auditorium 3
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Symposium friday
110 PM Introduction to the symposium Terrence
J. McDonald, Dean of the College of LSA
120 From before the Big Bang through the first
million years Katherine Freese, U-M Department
of Physics 150 The first million years through
the first 9 billion years Douglas O. Richstone,
U-M Department of Astronomy 220 The next 4
billion years making Earth a habitable
planet Stephen E. Kesler, U-M Department of
Geological Sciences 340 The tree of life
Darwinian chemistry as the evolutionary force
from cyanic acid to living molecules and
cells Nils G. Walter, U-M Department of
Chemistry 410 The tree of life exploring
evolutionary pathways through fossil
evidence Daniel C. Fisher, U-M Museum of
Paleontology 440 The tree of life exploring
evolutionary pathways from extant life Yin-Long
Qiu, U-M Department of Ecology and Evolutionary
Biology 510 Questions and discussion 530 13.7
billion years the summary Gordon Kane, U-M
Department of Physics
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Earth Watch

• Each time we meet, I would like 2 students to
  give a short presentation on a
• natural disaster (related to Plate Tectonics)
  that occurred in the past 20 years.
• Earthquakes, volcanic eruption,
• Tectonic setting reason that the natural
  disaster occurred
• Was it unexpected?
• How significant was this event compared to
  similar events elsewhere?
• What effect did the event have on the population?
• What was the response?
• Examples
• 2004 Sumatra earthquake and Asian tsunami
• 1994 Northridge earthquake
• 1995 Kobe (Japan) earthquake
• 1980 Mount St Helens eruption
• 1991 Mt Pinatubo (Philippines) eruption
• Your talk should last about 12-15 minutes, show
  about 10-15 power point slides

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Earth Watch
I put down your names, but forgot to save changes
to my power-point file 1/24 student1 student2
1/26 student3 student4 1/31 EXAM1 2/2 student
5 student6 2/7 student7 student8 2/9 student9
student10 2/14 student11 student12 2/16 studen
t13 VIDEO 2/23 EXAM2 2/28 Spring
break 3/2 Spring break 3/7 student14 VIDEO 3/9
student15 student16 3/14 student17 student18 3
/16 student19 student20
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Impacts on Earth and Geologic time
Geologic history is defined by how earth has
formed and evolved, and how the fossil record has
changed. Impact events play a major role, as we
shall discuss later
Figure 23.4
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Geologic time
HADEAN
Planet accretion
ARCHEAN
Continents formed
PROTEROZOIC
Primitive life
PHANEROZOIC
Evolutionary Big Bang
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Geologic time another class exercise

• Earth formed 4.567 Ba
• Suppose, we scale Geologic Time down
• to one year 365 days, and suppose
• Earth formed on mid-night January 1,
• and that now it is midnight of December 31.
• On what dates did we have
• First evidence for life (3500 Ma)
• The evolutionary Big bang (530 Ma)
• Dinosaurs extinction (65 Ma)
• On what date and at what time did we have
• First appearance of Homo Sapiens (120,000 years
  ago)
• Your birth (for simplicity, say it was 100 years
  ago)

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Earths differentiation I
Early in Earths history
Today
Differentiation of Early Earth rendered a
layered planet (much like an onion) comprised
of a dense (primarily iron), core, a light crust,
and a residual mantle in between
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Earths differentiation II
The energy released when a Mars-sizeobject
impacts Earth (this causedMoon formation) is
equivalent to100,000,000 megaton nuclear
bombs (one megaton bomb destroys a city)
Early in Earths history
Today

• Differentiation (due to Earths hot interior)
• early Earth is hot due to violent impacts and
• and the abundance of radio-active element (K40,
  U)
• the outer half of the earth is molten (magma
  (molten rock) ocean)
• the interior is hot and very soft it can easily
  flow

Differentiation the heavy stuff goes down, the
lighter stuff goes to the surface
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Earth as a layered planet I
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Earth as a layered planet II
Earths core Iron (Fe) and Nickel (Ni), which
are muchdenser than other elements, sank to
forma central core. It begins at 2900 km
depth. The core is liquid. Currents in the core
are responsible for the generation of
Earths magnetic field The inner-core is solid.
Scientists are stilldebating when it formed in
Earths history.
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Earth as a layered planet III
Earths crust The lighter elements (O, Si, Al),
floatedtowards the surface of the magma
oceanand formed the crust.The oldest crustal
rocks are 4.3 By. The crust is about 10 km thick
beneath the oceans and about 30-40 km beneaththe
continents. The thickest crust (70 km) isfound
beneath the Andes and the Himalayas.
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Earth as a layered planet IV
Earths mantle Between the core and the crust is
the mantle.It forms the bulk of the solid Earth,
and hasintermediate density. The mantle
rangesfrom 40 to 2900 km depth.
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Earth differentiation III

• Earths composition
• From the 100 elements 8 elements make up 99 of
  Earths mass.
• In fact, only 4 elements make up 90 of Earths
  mass.
• These are
• (1) Iron (Fe) 35
• (2) Oxygen (O) 30
• (3) Silicon (Si) 15
• (4) Magnesium (Mg) 13
• The core is almost entirely made out of Iron. The
  lighter elements form the crust
• (Note that crustal rocks on which we are standing
  are almost 50 oxygen).

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Earth differentiation IV oceans and atmosphere

• Two ideas
• (1) Air and water come from volatile-rich
• comets that impacted the Earth, which
• (we know now) consists of water-ice and
• frozen CO2.
• (2) The Wet-Earth hypothesis
• Planetisimals that aggregated into Earth
• contained ice, water and other gases.
• They were originally locked in minerals,
• but escaped as Earth melted during
• heavy bombardments.

Mostly Hydrogen (H), which escaped into outer
space Carbon-dioxide (CO2) Nitrogen (N) water
vapor (H2O) other gases (methane, CH4)