Transcript 1 ppt - DanaFrank

Warm Up: on p.1
What is history?
Briefly describe what you believe is earth’s history.
3rd Quarter Notebook
Date
Session
#
1/12-13
1
Activity
Page
#
Earth History
1
Earth Forces and Composition Review
2
Homework:
Study for test next class period
Review session Friday am
Please take your rainboots, etc. home!!
8.E.2 Understand the history of Earth and its life
forms based on evidence of change recorded in
fossil records and landforms.
8.E.2.1 Infer the age of Earth and relative age of rocks
and fossils from index fossils and ordering of rocks
layers (relative dating and radioactive dating)
8.E.2.2 Explain the use of fossils, ice cores,
composition of sedimentary rocks, faults, and
igneous rock formations found in rock layers as
evidence of the history of the Earth and its changing
life forms
TLW review forces and composition involved in
shaping earth’s history by modeling the rock cycle
with playdoh, closely reading an article &
diagram, complete text questions & completing a
quick write explaining earth’s consistent size.
Using clay and the expo marker, create the rock
cycle on your white board.
Use the expo marker for the arrows. Label the
processes the arrows represent.
Create an accurate model of the different
stations in the rock cycle using the clay.
tape onto
page 2
color code
Label:
oceanic crust, continental crust, mantle, inner core, outer core
Don’t label
these lines
yet!!
Crust
Continental Crust:
thicker, less dense,
older
Oceanic Crust:
thinner, more dense
Mantle:
thickest layer,
hot rock,
convection currents
that move tectonic
plates
Core
Outer Core:
liquid, circulates
around the inner
core, iron & nickel
Inner Core:
solid, iron
The circulation of the
liquid outer core
material around the
inner core causes
earth’s magnetic field
Read and annotate:
1st read: What surprised you
2nd: Relationship between layers.
Crust and Mantle vs. Lithosphere and Asthenosphere
Read and annotate
1st: scan article for
unfamiliar
terms.
2nd: read for what the
author
thought you already knew
3rd: read for surprise
Why do we use two names to describe the same layer
of the Earth? Well, this confusion results from the
different ways scientists study the Earth.
Lithosphere, asthenosphere, and mesosphere (we
usually don't discuss this last layer) represent changes
in the mechanical properties of the Earth. Crust and
mantle refer to changes in the chemical composition of
the Earth.
Lithosphere and Asthenosphere
The lithosphere (litho: rock; sphere: layer) is the
strong, upper 100 km of the Earth. The lithosphere is
the tectonic plate we talk about in plate tectonics. The
Asthenosphere (a: without; stheno: strength) is the
weak and easily deformed layer of the Earth that acts
as a “lubricant” for the tectonic plates to slide over.
The asthenosphere extends from 100 km depth to 660
km beneath the Earth's surface. Beneath the
asthenosphere is the mesosphere, another strong
layer.
Describe the components of the Lithosphere; use
evidence you see in the diagram to support your
answer.
Describe the characteristics of the Mantle, use
evidence you see in the diagram to support your
response.
The earth is broken into plates that
move….how do we know?
Alfred Wegener’s Evidence
Wegener noticed that earth’s continents appeared to
fit together like a puzzle. He hypothesized that they
were once joined as a single landmass – Pangaea
Evidence:
1.Mesosaur fossils in S. America and W. Africa –
nowhere else in the world
2.Climate: tropical plant fossils found in Greenland,
near the arctic circle, and Antarctica. South African
rock formations show evidence of ice sheet
scratches
3.Geology: rock layers in Brazil match those in W.
Africa. Appalachian Mtns have limestone similar to
Scotland’s Highlands
Harry Hess - Sea Floor Spreading
Scientists mapping ocean floor found huge underwater
mountain ranges—Mid Ocean Ridges
1. Ridges form along cracks in the crust. Molten rock
rises through crack, forms new crust, older material is
pushed away from the crack. Ocean trenches found
on sea floor. Oceanic crust sinks under continental
crust and melts into asthenosphere.
2. Drilling samples of sea floor reveal youngest rock is
closed to the ridge, oldest is further away. Oldest
ocean floor is younger than continental crust.
3. Magnetic Reversals of earth’s magnetic field
preserved in rocks.
Magnetic Reversals
•
•
•
Minerals in magma rising through the mid ocean ridge
align themselves with earth’s magnetic pole
As the rock cools, the minerals stay fixed in this position,
like a compass
Earth’s poles periodically reverse. The “stripes” of rock
along the ocean floor record these reversals.
page 1
Why does the size of the earth remain
relatively constant?
Using information reviewed in class today,
explain why the size of the earth remains
relatively constant.
(circumference, diameter)