Transcript 29. In this geologic cross-section

Monday 19AUG13
2nd - Get your reading guides out and read through Section
1 for your quiz. C
Continue with Section 2 PowerPoint.
Graphing Activity
3rd - 4th - Get your reading guides out and review section 2
for your quiz.
Continue with Graphing Activity.
Section 3 PowerPoint
• Section 3 - Reading Geologic Records
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http://www.stratigraphy.org/index.php/ics-chart-timescale
19. Scientists have divided Earth’s history into a
series of time segments that are collectively referred
to as the geologic time scale .
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20. Each of these
units is defined
based on geologic
and fossil records,
with division
between the units
marking some
major change such
as the appearance
of a new class of
living creatures or
a mass extinction.
http://www.blog.gurukpo.com/wp-content/uploads/2013/08/geological-time-scale.jpg
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Grand Canyon
21. Most of what we
know about our
planet’s history is
based on studies of
the stratigraphic
record - rock layers
and fossil remains
embedded in them.
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Photo: Arizona October 2012 Pamela R. Cox
22. Rock records can provide insights into what
(3) questions?
1. How were geological formations created and
exposed?
2. What role was played by living organisms?
3. How has the compositions of oceans and the
atmosphere changed through geologic time?
Photo: Arizona October 2012 Pamela R. Cox
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23.Scientists use stratigraphic records to
determine two kinds of scales.
24. Relative time scale refers to sequences –
whether one incident occurred before, after, or at
the same time as another.
25. Geologic time scale refers to – observations
from sedimentary rocks.
26. But is discontinuous and incomplete because
plate tectonics are constantly reshaping Earth's
crust.
http://traveltherockies.com/destinations/grand-canyon/grand-canyon-couples-favorite/
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http://www.education.com/study-help/article/earthscience-help-stratigraphic-classification/
27.Explain how plate tectonics are constantly
reshaping the earth.
As the large plates on our planet's surface move
about, they split apart at some points and collide or
grind horizontally past each other at others. These
movements leave physical marks: volcanic rocks
intrude upward into sediment beds, plate collisions
cause folding and faulting, and erosion cuts the tops
off of formations thrust up to the surface.
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http://www.expeditions.udel.edu/extreme08/geology/tectonics.php
What plates are around the United States?
http://www.youtube.com/watch?v=1-HwPR_4mP4Slide 10
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28. Give (3) examples of some basic rules for
determining relative ages of rock layers.
a. older beds lie below younger beds in
undisturbed formations
b. an intruding rock is younger than the layers it
intrudes into
c. faults are younger than the beds they cut
across.
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29. In this geologic crosssection:
a. How did layers E, F, H, I
and J come to be? They
were deposited through
sedimentation.
b. L and K represent
Fault lines
c. What do layers D, C and
B represent? Layers of
sediment added last.
d. What does A
represent? A volcanic
intrusion younger than
Sample geologic cross-section Geologic
the layers it
cross-sections are vertical slices through rock
penetrates.
formations. Earth scientists analyze crosssections to map an area's geological history.
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30. Use the sample geologic cross-section and
explain how fossil records can be used to determine
relative age.
Since fish evolved before mammals, a rock
formation at site A that contains fish fossils is older
than a formation at site B that contains mammalian
fossils.
31. Give an example of how environmental changes
can leave telltale geologic imprints in rock records.
When free oxygen began to accumulate in the
atmosphere, certain types of rocks appeared for the
first time in sedimentary beds and others stopped
forming.
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http://thenewennui.blogspot.com/2012/07/fourteen-fossils.html
32. Researchers study mineral and fossil records
together to trace interactions between
environmental changes and the evolution of living
organisms.
Ammonite fossils
among other
creatures in a
slab, 18 inches by
16 inches and a
stump of
petrified wood
http://www.hansenjewelry.com/minerals_%26_fossils.html
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33. What is radiometric dating and what does it allows
scientists to do?
Radiometric dating measures the decay of radioactive
isotopes in rock samples.
http://www.youtube.com/watch?v=cpnIxlDVmHw
This approach has been used to determine the ages of rocks
more than 3.5 billion years old . Once they establish the
age of multiple formations in a region, researchers can
correlate strata among those formations to develop a fuller
record of the entire area's geologic history.
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http://www.uky.edu/KGS/geoky/beneath.htm