Transcript Review - cloudfront.net

Review
• What are the 5 ways to absolute age
materials?
Review - Isotopes
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(SPECIAL ATOMS)
Atoms that belong to the same element but have
different atomic masses are isotopes of one
another.
Isotopes of the same element have the same # of
protons and electrons but a different # of neutrons.
All elements have isotopes.
Isotopes are the reason why atomic masses are
decimals and not whole #’s.
Some isotopes are radioisotopes, which means
they are unstable and their nucleus breaks apart.
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Release energy.
Turns the isotope into an atom of a different element.
Review
Atom A has 7 protons, 7 neutrons and 7 electrons.
Atom B has 8 protons, 7 neutrons and 6 electrons.
Atom C has 8 protons, 7 neutrons and 7 electrons
Atom D has 7 protons, 8 neutrons and 7 electrons.
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Which 2 atoms from the list above
are isotopes of the same element?
How do you know this?
Add to table of contents:
• Fossil Lab
• Fossils
Pg. 48
Pg. 49
• Open Earth Science Textbook to page 197
Fossils
Pg. 49
• Fossils – the remains of animals or plants that
lived in a previous geological time.
Fossils are an important part of relative
and absolute aging of rocks.
We already learned which type of rock fossils
are most likely to found in. What was it?
• How fossils form:
1. Mummification – in dry areas where bacteria
don’t survive.
2. Amber – insects trapped in sticky tree sap.
3. Tar seeps – animals get stuck in sticky tar.
LaBrea Tar Pits in California
1910
• Today
Only 1 human has ever been found in
the LaBrea Tar Pit a 9,000 year old
woman(17-25 yr old)
Don’t Write
• On February 18, 2009, George C. Page Museum formally
announced the 2006 discovery of 16 fossil deposits which
had been removed from the ground during the
construction of an underground parking garage for the Los
Angeles County Museum of Art next to the tar pits.[9]
Among the finds are remains of a saber-toothed cat, six
dire wolves, bison, horses, a giant ground sloth, turtles,
snails, clams, millipedes, fish, gophers, and an American
lion.[9][10] Also discovered is a nearly intact mammoth
skeleton, nicknamed Zed; the only pieces missing are a rear
leg, a vertebra and the top of its skull, which was sheared
off by construction equipment in preparation to build the
parking structure.
• 4. Freezing – too cold for bacteria
Otzi and wooly mammoths
• 5. Petrification – minerals replace organic
material to form a mineral replica.
Petrified wood
• 6. Imprints – carbon-rich film left from plants
and fish.
• 7. Molds & Casts – empty cavities(molds) fill with
sand or mud and hardens(cast)
• 8. Coprolites – fossilized dung
• 9. Gastroliths – stones in digestive systems to
grind up food.
• While some fossil gastroliths are rounded and polished,
many stones in living birds are not polished at all.
Gastroliths associated with dinosaur fossils can weigh
several kilograms. Stones swallowed by ostriches can
exceed a length of 10 centimetres (3.9 in). Also found in
chickens and crocodiles.
• Why are most fossils found formed from the
bones or shells of animals?
• Index fossil – only occur in rock layers of a
particular age.
Scientists can use index fossils to relative and
absolute age rock layers.