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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Quiz 14 S4 12/12 12/12 12/19 1/16

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