Transcript Linking Asteroids and Meteorites through Reflectance

Conversations with the Earth
Tom Burbine
[email protected]
Quiz
• Monday for M,W, Th class
• Tuesday for T, Th class
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Covers material after last quiz
Chemistry
Global warming
Dinosaur extinction
Geologic time scale
• System of measurement relating stratigraphy to
time that is used to describe the timing and
relationships between events that have occurred
during the history of the Earth.
Stratigraphy
• Stratigraphy – study of rock layers and layering
Original Horizontality
• Layers of sediment are originally deposited as an
even, horizontal layer
• Layers inclined at angles were moved by
disturbances after deposition
Superposition
• Each layer was deposited on top of older
preexisting layers below
Principle of Superposition
http://earthsci.org/fossils/geotime/time/Super.gif
Exercise #3
• Question 1
• What is used to differentiate between different
time periods?
• Question 2
• How long ago did the dinosaurs become extinct?
• Question 3
• How long were there dinosaurs living on the
Earth?
• Index fossils are fossils used to define and
identify geologic periods
• The shorter the lifespan of a species, the more
precisely different sediments can be correlated
K-T layer
• K-T layer is the boundary between the Cretaceous (K)
and Tertiary (T) time periods
• Clay layer that is found all
over the globe
Colorado
Wyoming
Italy
K-T Boundary
• 65 million years ago
• Boundary in the rock
record separating the
Cretaceous and Tertiary
Periods
• Corresponds to one of the
greatest mass extinctions
in history
• ~1 cm global layer of clay
separating the two periods
• A reason for the extinction
was proposed by Walter
Alvarez and Luis Alvarez
in 1980
• Question 4
• Why is a high concentration of iridium evidence
that an asteroid hit the Earth?
Iridium
• Iridium (Ir) is a chemical element with atomic
number 77
• Iridium is one of the least abundant elements
(0.001 ppm) in the Earth's crust
• Iridium is much more abundant in meteorites
(0.5 ppm or higher)
What happened?
• An asteroid roughly 10 km (6 miles) across hit
Earth about 65 million years ago.
• This impact made a huge explosion and a crater
about 180 km (roughly 110 miles) across.
• Debris from the explosion was thrown into the
atmosphere, severely altering the climate, and
leading to the extinction of roughly 60% of species
that existed at that time, including the dinosaurs.
Environmental Damage
• http://www4.tpgi.com.au/users/horsts/climate.htm
• The worst hit organisms were those in the oceans.
• On land, the Dinosauria of course went extinct,
along with the Pterosauria.
• Mammals and most non- dinosaurian reptiles
seemed to be relatively unaffected.
• The terrestrial plants suffered to a large extent,
except for the ferns, which show an apparently
dramatic increase in diversity at the K-T
boundary, a phenomenon known as the fern spike.
• Pterosaurs were flying reptiles
• Dinosaurs lived during the Mesozoic Era, from
late in the Triassic period (about 225 million
years ago) until the end of the Cretaceous (about
65 million years ago).
• Question 5
• What species today are direct descendants of the
dinosaurs?
Archaeopteryx
• Modern birds are considered
be the direct descendants
dinosaurs
• Idea first formulated in 1860s-1870s
to
of
Rahonavis
• http://www.hulu.com/watch/63729/nova-the-fourwinged-dinosaur
Any Questions?