Post on 12-Jan-2016
MondayJanuary 7, 2013
(Types of Fossils)
The Launch PadMonday, 1/7/13
What two pieces of evidence are most commonly used by
geologists to construct the Geologic Time Scale?Rock layers
Fossil recordsCan you explain why these are
used?
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Recent Events in ScienceBillions and Billions of Planets!
Read All About It!http://www.nasa.gov/mission_pages/ke
pler/news/kepler20130103.html
Look up at the night sky and you'll see stars, sure. But the sky is also filled with planets -- billions and billions
of them. That's the conclusion of a new study by astronomers at the California Institute of Technology in
Pasadena, which provides yet more evidence that planetary systems are the cosmic norm. The team made
their estimate while analyzing planets orbiting a star called Kepler-32 -- planets that are representative, they
say, of the vast majority of planets in our galaxy and thus serve as a perfect case study for understanding
how most of these worlds form. "There are at least 100 billion planets in the galaxy, just our galaxy," says John Johnson, assistant professor of planetary astronomy at Caltech and coauthor of the study, which was recently accepted for publication in the Astrophysical Journal.
"That's mind-boggling.“ "It's a staggering number, if you think about it," adds Jonathan Swift, a postdoctoral student at Caltech and
lead author of the paper. "Basically, there's one of these planets per star."
Fossils
Fossils - Evidence of Past Life Fossils, the remains or
traces of prehistoric life, are important
inclusions in sediment and sedimentary rocks.
The study of fossils is called
“paleontology.”
Fossils - Evidence of Past Life Fossils are the remains or traces of prehistoric
life.
Types of Fossils The remains of relatively
recent organisms may not have been altered at all. Examples include bones,
teeth, and shells.
Fossils - Evidence of Past Life Far less common are entire animals that have been fossilized because of unusual circumstances. These
have been only slightly modified, and are referred to as “mummified fossils.”.
Fossils - Evidence of Past Life Modified Fossils
Petrified fossils have had the small cavities and pores of the
original structure filled with precipitated mineral matter.
Fossils - Evidence of Past Life Modified Fossils
Replacement fossils have had the cell material removed and replaced with mineral matter.
Fossils - Evidence of Past Life Modified Fossils
Mold and cast fossils - when a shell or other structure is
buried in sediment and then dissolved by underground
water, a mold is created. The mold reflects only the shape and surface markings of the organism; it does not reveal
any information concerning its internal structure. If the
hollow spaces are then filled with mineral matter, casts are
created.
Fossils - Evidence of Past Life Modified Fossils
Carbonization fossils are created when fine sediment encases the remains of an organism. As time passes, pressure squeezes out the
liquid and gaseous components and leaves behind a thin residue of
carbon.
Fossils - Evidence of Past Life Modified Fossils
Impression fossils are replicas of the fossil’s surface
preserved in fine-grained sediment.
Fossils - Evidence of Past Life Modified Fossils
Amber-preservation fossils are hardened resin (sap) of
ancient trees surrounding an organism.
Quick Quiz
The study of fossils is called _______________.Which of the following fossils would yield the greatest amount of information about the ancient organism?
paleontology
__________ are the remains or traces of prehistoric life.
Fossils