Our next few weeks we will be taking a look back in time. The Geologic Time Scale chronicles life on Earth and how it changes.
What evidence is there for the current understanding of our geologic time scale?
How do fossils form?
How can we tell the age of a fossil?
Do you have a fossil you would like to share with the class? Worried that it would be lost at school? Submit a photo and all the info you have on the fossil to the classes virtual museum. You can bring the fossil in for a picture or submit a picture.
Week 7 contracts can be found here. Over the next few weeks with WKCE testing and assemblies, schedules will be different. So, this weeks contract will be spread over the next two weeks, due November 12.
20 comments:
You can tell the age of a fossil in two ways: exact and relative age. Relative age is easier to understand. If you want to figure out relative age you can look at what layer of rock it's in. Exact age is much more complicated. In order to figure out exact age you figure out its radioactivity. The more radioactive, the younger the fossil is. A chemical called uranium, then, eventually turns into lead. By figuring out the radioactivity levels, you can also determine the fossil's half life.
Heres an example: Lets say uranium takes 700 million years for half (50%) of the fossil to turn into lead. At that point, there is 50% uranium and 50% lead in the fossil after that 700 million years. Then 700 million years later that fossil has changed yet again. Suddenly that 50% turns into 25%. 700 million years later, half of that uranium turns into lead. 25% turns into 13.5% for the uranium levels.
The lead levels increases all the while, because the older the fossil the less radioactivity and uranium turns into lead.
Mag,
I know the book describes it as a bar graph but the change is not so "sudden"
Nice description of one of the more difficult concepts to understand in this unit.
We understand our current geological time scale because of fossils,fossils are traces or remains of living things from a long time ago. A foosil is formed when dead remains of animals is replaced by minerals to make the the animals skeleten hard rock. You can tell the age of a fossil by using radioactive dating,looking at the layer of rock were you found the fossil, and by useing relative and absolute age.
There are many ways that we can identify how old a fossil is. The most common way is by identifying how old the rock is that is surrounding the fossil.
you can look at how far it is in the ground
are there any dinosaurs that weas found in Wisconsin
have you ever seen a dinosar fossil and if so whats your favorite
You can tell the age in two ways through absolute age which involves finding the amount of radioactive isotopes in a fossil and finding how many are left because we know the half lifes of certain radioactive isotopes
or rel;ative age by comparing fossils to the fossils around it
example: a fossil buried deaper is older than a shallower fossil
Fossils are formed when the organism gets buried after it dies,decays slowly, and then mineral takes its place. You can tell the age of the fossil by determining the age of the rock around it, or finding the half life of the fossil.
For a fossil to form an animal or plant must be trapped in a material. Mostly, fossils are found in sediment. Layers of sediment will get into the remains .The actual remains that are found aren't the animal or plant.It's really rock that took its place. Minerals then replace the space that was once the remains. The mineral hardens and makes an impression of the animal or plant. Fossils can be in many types there are imprints, molds casts, tar, ice, amber, mummified, carbon films, and petrified.
what ways do fossils form how many ways are there
5 things I learned from fossils
1. Identification of the animal
2. Animals that lived there
3. Plants that grew there
4. How the animals behaved
5. If the animals were hurt by an outer animal
well wouldnt the animals now not to go in it they start to get stuck with thte first foot they step into the tar?
Fossils form when they are dead for thousands of years and they are in sedimentary rock. They get preserved so only the guts and organs decay but not the bones/skeleton.
How can the half-life of certain elements be hours when others can be thousands of years?
Fossils can tell us what life might have been like a long time ago. The La Brea Tar pits well preserved the bones.
Fossils can tell us what life might have been like a long time ago. The La Brea Tar pits well preserved the bones.
Fossils are important evidence of past occurences. Fossils are remains of living things from a while back. Fossils can tell us about different organisms, like dinosaurs, that are extinct. Fossils can exist in different forms. Most fossils are hardened animal remains like shells, bones, and teeth.
If the bone eventually decays, then what replaces the bone in order for it to become a fossil?
If the bone eventually decays, then what replaces the bone in order for it to become a fossil?
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