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Transcript of Fossils
- A break or crack in the Earth's surface
-a place where an old, eroded rock surface is in contact with newer rock layers; when this happens there is a gap in the geologic record because some layers have been lost because of erosion
- an igneous rock layer formed when lava flows to the surface and hardens
- an igneous rock formed when magma hardens beneath the Earth's surface
- a sample of rock, soil,snow or ice; you get it when you take a hollow tube and push it into the area you want a sample from; when you take it out, it contains all the different layers of materials you are testing , then slide the material out of the tube and you can see a small section of what the inside looks like.
- a core sample generally taken from an ice cap in the polar or mountain region; scientists study the melting and freezing of the ice to determine climate changes in the environment
- Carbon is consistently cycled in a living organism. As soon as a living organism dies, no more carbon is put into the organism. The carbon breaks down in a steady rate. To determine the absolute age of an organism, scientists study how many times carbon isotope has broken down in half.
- when the unstable isotopes of a dead organism break down and form another element
- when a living organism breaks down
- the time it takes for a radioactive atom to decay
- a fossil formed when an organism buried in sediment dissolves, leaving a hollow area.
- a type of fossil that proves evidence of ancient organisms; it's not the actual object,but something they left behind (example-footprint)
- identifying the number of years since an object was formed (can be in a range of years)
- a fossil that is a copy of an organism's shape; formed when minerals seep into a mold
- fossils of widely distributed (found in many locations) organisms that lived during only one short period; index fossils are used to help determine the age of rock layers; because they know the organisms lived only during a certain, specific, amount of time, all other items in that rock layer are inferred to be the same approximate age as the index fossil; items in layers above the fossil are younger and the ones below it would be older
- a continuous loop in which old rock is broken down and made into new rock
- broken down pieces of rock
- the type of rock that is made of hardened sediment; rock that is made by compressing bits and pieces together until it is pressed into new rock
- any rock that is put under high pressure and/or temperature so that it alters the shape/structure of the existing rock
- melted rock, it must be underground to be called magma
- melted rock that is above ground
- rock that was formed from lava that has cooled,"fire rock"
- the trace of remains of an organism that lived long ago , most commonly preserved in sedimentary rock
comparing the age of an object to the age of another
Law Of Superposition
- younger layers are on top and older layers are on the bottom
What is a fossil?
A fossil is what is left of something that lived long ago, like a dinosaur.
Notes from class
Molds and Casts
A mold is formed when something that has died completely decays leaving a hollow spot in the ground. A cast is formed when minerals seep into a mold and harden, forming a copy of what was originally there.
Index fossils can be found in many locations and lived during a short period in time. They help paleontologists determine how old the rock layers are. Any other items found in the rock layer are inferred to be as old as the index fossil. An example of an index fossil is a trilobite.
The Law of Superposition
The Law of Superposition states that the oldest layers are on the bottom and the younger layers are on the top.
In this video, there is magma coming out of a volcano. The lava then hardens into igneous rock. This is an example of an extrusion.
Intrusion happens when magma goes though the Earth's layers of rock. The magma never reaches the surface, so it hardens. Intrusions are younger than the layers they go through.
A fault is a break or crack in the earth's crust along which rocks move.
The Rock Cycle
The Rock Cycle is how earth recycles its materials. It starts off as rock, then the bits and pieces get compressed into a layer of sedimentary rock. Layers build on top of each other. Eventually there is so muck pressure put on the rock that it becomes metamorphic rock. The shape of the rock changes. Magma is formed. An extrusion will bring the magma to the surface, making it lava. It hardens into igneous rock. The cycle will start all over again.
Trace Fossils are things (such as footprints) that prove the activities of a dead animal.
How Do Fossils Form?
Fossils form when an animal dies and sedimentary rock builds up on top of it.
While it is underground, the body decays except for the bones. Erosion wears off the soil on top of the fossil exposing the bones.
Bill Nye Clip
-If a fossil is found on an upper layer of Earth, what can we assume about WHEN the organism died?
-What type of rocks are fossils common in?
- List the reasons you think that jelly fish can't become fossils.