Fossils Through Geologic Time

How can we determine the age of a fossil? If different fossils are found in different layers of rock, could you tell which fossils are the oldest? The youngest?

62 thoughts on “Fossils Through Geologic Time

  1. Im gonna make a mad guess, but I think it has something to do with how worn, and deep, the fossil is found. The deeper it was found, the more weathering effected it, and the more worn the older, for obvious reasons.

    • Now that I know that my original claim is completely wrong, I will make a new one. Using a mass spectrometer, scientists can determine how old a rock is compared to other layers of rocks. The machine measures the rate of uranium in the rock that has turned to lead, through some simplistic math, they can determine how old the rock is up to four billion years.

  2. I think that a fossil age can be found by seeing how deep they were buried, where the fossil formed, and how well put together the fossil is. By seeing how deep the fossil was buried could tell us how old it is because I think that is a fossil is buried deeper, it could be an older fossil, and if it more shallow, then it could’ve been formed more recently. Where the fossil formed could tell us many things, because the place could have had a climate change, a species could’ve gone extinct, etc. So, we could see the fossils eating habits, and how they lived. I think that how well the fossil is put together could tell us many things, if it more well out together, it could possibly be a new fossil. If the fossil is more worn, it could be older.

    • I claim that finding the age of a rock is possible, but it it isn’t as easy as I thought it was. You can determine the age of a rock in various ways, like grinding the rock into tiny bits, and using a mass spectrometer to see how much uranium turned to lead. Another way is using index fossils, which have spread widely across the world and that have recently gone extinct shortly after they existed. They use these to compare the age of different fossils and rocks to them. Using only one fossil that was native to a certain area would be almost useless, as it doesn’t tell us much about the other fossils.

  3. I claim that you might be able to determine the age of a fossil measuring its depth in the lithosphere. The deeper you can find it, I think it would be older. Maybe you could measure how many minerals are in it that were around before that aren’t now if we have that information. My evidence is that the deeper rocks are, the older they are.

    • I claim that we can loosely determine the age of a fossil and the time period they lived in. One method of determining the age of a rock in relation to others is grinding up a rock and finding out how much uranium in the rock has changed to lead using a mass spectrometer. Another method would be to use index fossils. Index fossils are fossils that have been widely distribute across the world in different places and have existed for relatively short periods of time before they went extinct. My evidence is that there would be no point in trying to use the fossil of an organism that only lived in one place and/or lived for a very long period of time because that would make for a stratigraphic history of primarily one species that wouldn’t help explain anything if you were comparing the ages of different rocks and fossils.

  4. I claim that if a fossil is found lower in the earth that would make it older than one that is near the surface. My evidence is that for an organism to become a fossil they have to be buried under rock so if its lower then that means it was buried a lot longer than one that is towards the surface more.

    • I claim that to find out how old a fossil is you could use index fossils. My evidence is that in some fossils, dating back millions or billions of years, they can contain uranium. Over millions of years that uranium turns to lead. From how much lead is on or inside the index fossil we can figure out how old it is. Another way to see how old it is, is seeing how deep in the Earth. If it is lower down in the Earth that tells us it is older than how higher up in the ground it is, if its higher up its younger.

  5. I am just going to make a hypothesis and say that we can can determine the age of a fossil by looking at how dense rocks are where the fossil is buried, looking and guessing how old the rocks are, maybe looking at how dry the soil is. We can probably determine how the weather/climate was back then and looking at how deep the fossil is buried. I believe that we can answer this question by saying that you can determine what fossils are oldest and youngest by looking at how old the rocks are. I claim that where dryer places are the oldest fossils could be there. I hope that I can eventually find a fossil myself as well.

    • I claim we can determine the age of a fossil using stratigraphic correlation to find the absolute age of rocks etc. My evidence is when going through the process of grinding up the rocks and finding how much uranium self- destructed into lead and using a mass spectrometer and using advanced mathematics to find how long ago it formed is a long and expensive process. Sometimes we can’t find the certain age of a fossil but it is the best way to try index fossils help this process. An index fossil had to live a short life before going extinct and has to be widely distributed around the world, they correlate strata around the world! They help to find the layers of rocks and how old they can date back to.

  6. I claim that you can determine how old a fossil is by how deep it is in the earth’s crust. If fossils are found in different layers of rock the fossils closer to the surface would be the newest ones. The fossils you can find deeper in the ground are older. The evidence I have to support my claim is that organisms take thousands of years to fossilize. During that time there will be more buildup of sediments burying some fossils deeper and new ones layer on top closer to the surface.

    • I claim that you can determine how old a fossil is by looking at the different layers of the rock and the fossils found on the bottom layers are the oldest. The fossils found in the top layers are the newest ones. The evidence I have to support my claim is The Law of Superposition states that “In an undisturbed horizontal sequence of rocks, the oldest rock layers will be on the bottom, most recent on top.”

  7. I think how we can tell how old fossils are is how deep the fossil. The younger fossils could be more shallow than the older fossils. And by how rough a fossil is like if you find a fossil deep into the earth and its smoothed down but if you find a fossil that was found shallow and it was rough that could mean its a younger fossil. or maybe where it is found.

    • I claim you can determine how old a fossil is by using a mass spectrometer and using uranium to find out the rocks age. Another way to find which rock is oldest is if the rock if the uranium turned to lead then using simple mathematics the scientist’s can find out how old the rock is.

  8. I claim that fossils that fossils that are old probably covered in dirt and are rusty and the young fossil are probably not so rusty or covered in dirt that much. The old fossils are buried further down and the young ones are buried but their not that deep in the ground.

    • I claim that we can tell how old the fossils are by using a machine called mass spectrometer. It uses uranium to measure it, tells us how old the fossil is. The other we could tell how old the fossil is by seeing how far it’s deep down in the ground. The more it’s buried the fossil is old, and when the fossil is not the deep down it’s younger.

  9. i claim that in order to tell how old a fossil is you have to know what country around the world. the fossil is to determine if the land is old or not to see what the environment is like or how deep it is in the ground. i also claim the the deeper down the fossils are determines how old they are and the ones closer to the surface are the newer fossils.

  10. I claim that you can tell the age of a fossil by its encasement around it or by how far its buried. You could test the layer around the fossil and you can take a slight guess on how old it is or you could see how deep the fossil was buried and ethier compare it to other fossils that was buried as close or just as deep as the fossil you found.

    • I claim that you can determine the age of a fossil by using the process stratigraphic correlation and using the scale of geological time with radioactivity and uranium. Using stratigraphic correlation is matching equivalent layers that have different times and different materials. One way to determine how old a fossil is with this process is with a index fossil. A index fossil had to live a short life before going extinct and has to be widely around the world. The stratigraphic correlation doesn’t tell you the age of a fossil directly but only how old it is compared to other layers/fossils. The scale of geologic time use radioactivity to help determine the age by how much uranium, which is a chemical element of radioactivity, has turned into lead, uranium self-destruct into lead, by using a mass spectrometer.

  11. I think that we can tell the age by how deep and how it looks. the oldest fossil would probably be on the bottom because it’s the oldest. would be on Top because it the youngest and probably died really early on.

    • I claim that we can tell the age of a fossil by using methods by geologists it does involve radioactivity. Yes we can because of index fossil they must have existed for a short periods of geologic time.

  12. I claim that you could find how old a fossil is by seeing how deep it is. My evidence is if you dig underground and find a fossil in under about 10 minutes then it most likely was not there long. If you dig for a longer period of time it was probably there longer.

    • I claim that using a mass spectrometer helps geoscientists find the age (oldest to youngest) of a fossil. My evidence is by looking at other layers of rocks and seeing which one has the same time layers. You could also find out their ages by doing some math and measuring the rate of uranium in a rock.

  13. I claim that you can determine the age of fossil on how deep it is in the ground or possibly by the rock or sediment surrounding it. You could also possibly test the soil looking for the age of it. The deeper the fossil is in the ground the older it might be.

    • I claim that in order to tell how old a fossil is is a lot harder than I originally thought, A lot of the time scientists can’t find the fossil or haven’t discovered the fossil that was living before that fossil making it hard to know where that fossil fits into the geologic scale. Scientists compare the stacks or stratigraphic sections against one another to get the best estimate of time. Scientists also use radioactivity to help discover the age of a fossil. Some minerals have atoms that contain uranium, they then grind up a rock to see how much uranium there is but no lead. They use a mass spectrometer that measures the rate of uranium in the rock that has turned to lead and then simple math to determine the age of the rock.

  14. I think if you are a morgue doctor then you could possibly tell how old the fossil is, or how old the organism was since it died. My guess/claim is that you could tell how old it is due to how much the fossil lost it’s color and how much dirt is in the creases. Same goes for telling which is the oldest or youngest fossil in a rock, you tell how much color it lost for oldest and how much color it didn’t loose for the youngest.

    • My new claim is that you can tell how old the rock is by using an instrument called the mass spectrometer. Using that scientists will be able to tell that the bottom layer is the most oldest while the top layer is the youngest or recent layer, by doing that they have to grind up the rock to see how much uranium in it that has turned into lead.

  15. I claim that to tell the age of the fossil you look at the depth because if the fossil is high up that can show that the surface above it has had time to wither away and as it withers away the fossil rises to the fossil becomes uncovered by the layer that was above it.

  16. I think that we can determine the age of a fossil by using carbon dating, led dating, and uranium dating, and looking at how deep in the earth the fossil is, in which case, the deeper the fossil is, the older it is, the less deep, the younger it is.

  17. I claim that when you look at a fossil you can tell how old it is by testing how hard it is and where it was found. Where it died can also give clues to how old a fossil is. It is easier to find fossils in damp climates, or climates with more precipitation. It is harder to find fossils in desert climates. Yes, you can tell by just looking at the layers of the rock because the older fossils will be at the bottom layer and the new fossils will be higher up in the layers. My evidence is when Anika came in to class and showed us the rock layers with fossils inside them.

  18. I claim that we can make a guess as to how old a fossil may be based on how deep it was buried, the quality it is in, what species it may be, and if the species is extinct. A fossil that may be older probably has close to or no color. A fossil that is younger will probably be found just below the ground or on surface.

    • I claim that we can find out how old a fossil may be using methods that involve radioactivity, and the layer of rock the fossil may be in. My evidence is that using the layer of rock the fossil is in can give us a good idea of how old it is by showing us how much sediment and mud might’ve buried the fossil over time. By using this method we can guess that the oldest fossils would be on a lower layer while a newer fossil will be in a higher layer. Using methods that involve radioactivity can most likely give us a more accurate answer than looking at rock layers by using minerals with atoms of the radioactive chemical element uranium to see how old the rock a fossil is buried in may be.

  19. I claim that you can determine hold old a fossil is by observing the rocks or sediments around the fossil, or if the inside of the fossil contains crystals. Or if the fossil is deep into the ground meaning it has been covered in layers of sediment over time. If the fossil is young it would not contain as much crystals or be not as deep into sediments.

    • I claim that the deeper the fossil is the older it is. My evidence is that the uranium in the fossil is used by scientists to measure the age of a rock or fossil. The scientists look at the uranium and see if some of the uranium has turned into lead that can be used to measure the age of a rock or fossil. If there is no uranium or lead in a fossil you can tell the age of the rock or fossil by looking at how deep the fossil is or you can look at the age of rocks and fossils around the rock or fossil you are studying.

  20. I claim you can determine the age of a fossil by maybe how old it looks or maybe it depends on what type of fossil it is. I think you could tell which one is the oldest or the youngest if they were different layers of rock for an example. If there was a fossil that was above another fossil that fossil could be younger. My evidence is this is what i think would happen also what i know.

    • I clam that the fossils at the bottom of the rock layers are the oldest and at the top of the rock layers are the youngest. We can also tell the age of a fossil with uranium and the lead from the rock using how much lead there is. My evidence is this is what I know what happens at the rock layers and what we did in class.

  21. I claim that to determine the age of a fossil you should look in the rock around it and see if you can identify the age of the rock. Also if you can’t figure out the rock’s age you should look and figure out when the animal lived. My evidence is that with most animals that are fossilized you can see the time in the rock or by when that organism lived. You could tell what fossil was the oldest, because it would be farther down.

    • I claim that to determine the age of a fossil you can use the relative time scale or a mass spectrometer. My evidence is the relative time scale is used by looking for index fossils in the area. The index fossils are fossils that can be found all over the world, but only live a short while. The index fossils can be used like mile markers. A mass spectrometer takes ground up rocks or minerals and using radioactivity can see how much uranium and lead is inside it. The scientists then use a mathematical formula to figure out the age of the rock based on the amount of uranium turned to lead. Also, if different fossils are found in different layers of the rock the one lower would be older, because rocks grow new layers from the top.

  22. I claim that the deepest rocks are the oldest rocks because the younger layers cover the oldest layers of rock.My evidence is the oldest rock might have fossils in it and fossils are quite old so sort of estimate the time fossil was formed and just reverse engineer that to estimate the age of the rocks.On the other hand the youngest rocks are at the top most layer because the newest rock is formed from new sediment.

  23. I claim that the age of fossils can be determined by checking to see if there are other organisms living inside the fossil. Fossil age can also be figured out by checking how fragile it is. Younger fossils might still be intact; there will be more pieces to a younger fossil. Yes, I claim that you can tell which fossils are older and younger in rock layers. My evidence is that the oldest fossil is usually found deeper underground or in the bottom layer. From what I learned in class, sand and soil build layers on top of one another. The oldest fossils are harder to find because they will be buried under layers of sand and soil. The younger fossils will be easier to find because they will not have as many layers on top of them.

    • I claimed that there is a way to find out how old fossils are.
      This is my evidence.
      A mass spectrometer can be used to discover how much uranium has been turned to lead in the rock.
      Rocks as old four billion years can be dated this way

  24. I claim that we can tell the age of a fossil by the layer of rock/soil that it is in. The fossils at the top are the newly fossilized objects and the fossilized objects at the bottom are the old ones.

    • I claim that I was correct and that you can tell the age of a fossil. My evidence is you can do this by looking to see what layer the fossil is in. For example if the rock is layered from bottom being the oldest and the top being the youngest, And if the fossil is near the bottom then you know that the fossil is older than the ones at the top.You can also use mass spectrometer to read the amount of uranium is in the fossils to see how old the fossil is.

  25. I think you can determine the age of a fossil by how deep it is buried in the earth or if you could see if its worn out like if it has cracks in the fossil. If a fossil is young it is less deep than the deeper rock. If fossils have more like sediment then you can tell if the rock is old or if you have less sediment then its young.

  26. I think that how you find out how old a fossil a is how far they were buried the deeper it is the older it is. The more shallow it is the younger it is, like the type of rock how many layers there are on top of it the more layers of rock there is on fossil the older it is. The less layers of rock on the fossil the younger it is.

    • I claim that the oldest fossil is at the bottom of the rock layer and the youngest rock is at the top layer of rock. My evidence is looking the layers of rock and using some math and measuring the rate of uranium in a rock.

  27. I claim that a fossil’s age can be estimated based of both its age and depth in the ground. A fossil’s age can be determined based off of multiple dating techniques, also. A new fossil can be found near the surface. An older fossil can be found deeper down. This is not always reliable, though, as it can be affected by rainfall, other organisms, and many other factors.

    • I claim that my last claim was false. The Law of Superposition is used to estimate how old a rock is compared to other rock layers. This Law states that in an undisturbed rock sample, the oldest rock is the farthest down, and the youngest is near the surface. A better, more precise method is to test the radioactivity levels in a layer of rock. Some minerals contain trace levels of uranium, and this uranium sometimes self-destructs and changes into lead. Scientists grind up these rocks with uranium traces and then test the sediment, using a device called a mass spectrometer. With this device, scientists can find out exactly how old a rock is, up to 4 billion years. They can also tell a rocks age if it is in different layers, something the Law of Superposition could not.

  28. I claim that to determine the age of the fossil is that all you have to do is see what layer of rock the fossil it is in. To tell the and youngest and oldest fossil apart. All you have to do is look at the layer of rock it is in. at the top layer of rock is the oldest because it was the first and it was pushed up.

    • I claim that to to see which of the fossil you have is the oldest all you have to do is see what layer of rock the fossil it is in.To tell the and youngest and oldest fossil apart. All you have to do is look at the layer of rock it is in. If it is at the bottom then it is older because it has been down there longer the higher it is is the newer because it is in a newer layer that was formed. Another way to see the age is to use an mass spectrometer and mesher the uranam count.

  29. I think that you can find out how old a fossil is by knowing how far they were buried into the ground and I think the deeper they are buried the older they are.You can also find out how old a fossil is by seeing how cracked it is.

  30. I claim that to determine the age of the fossil is how far down the fossil is in the ground or how far up the fossil is in ground level and if that animal or amphibian exist anymore. The fossil record book can also show how old a fossil is or was.

  31. I claim that you can determine the age of a fossil by the the depth you find it in the Earth. If it died 180 million years ago, it would be deeper in the ground than an animal that died 80 million years ago. I think you would also be able to determine the age by how old it looks.

  32. I claim that the deeper the fossil is the older it is and the closest one to the surface is the youngest but if there is a fossil that can be found throughout the first couple layers chances are that that is the oldest. You can also tell the age of a fossil by testing the uranium count because over time uranium turns to lead so the higher lead count a fossil has the older it is using mathematics and a mass spectrometer. Finally you can compare a fossil to an index fossils which are fossil distributed around the world that existed for short periods of time. they us these types of fossils for correlating strata around the world.

  33. I claim that you can figure out how old a fossil is by using the mass spectrometer.My evidence is they look through the layers and how much uranium is turned to lead over the years. Then they use some simple mathematics to figure out how long ago the mineral was first formed You can also tell if a rock is at the top it is younger but if it is at the bottom it is older.

  34. I claim that minerals contain atoms of radioactive chemical elmement called uranuim. This causes the atom to self destruct. then they grind against a rock to collect tiny minerals that started out with uranuim. Then they use this intrument called mass spectrometer to measure how much uranium has been changed. Then after that they can tack rocks as old as four billion years ago.

  35. I claim that the older a fossil is, the farther down the rock it is fossilized in will be. My evidence is that many of the oldest fossils were found in quarries at the very bottom of the quarry and the most recent fossils were at the top. scientists also use widely spread, and short lived fossils to tell how long ago a species lived. They also use radioactivity to pinpoint a time when a species lived by using uranium in the fossil that has self destructed into lead atoms and figuring out when that uranium self destructed, they can figure out how long a fossil has been fossilized.

  36. I claim that through a methods of radioactivity you can determine the age, my evidence supports my claim because of machinery used by scientists called a “mass spectrometer”. The machine works by comparing a sample of rock to another layer of rock, it will then determine the amount of uranium in the rock sample that has turned to lead. Scientists will now use the data from the machine and by “using some simple mathematics” to determine the age, many rocks that are as old as four billion can be measured or “dated this way”.

  37. I claim that you can date fossils by using how radioactive they are. How this happens is some fossils contain uranium atoms, and sometimes uranium explodes to form lead atoms so scientists grind up the uranium then they see how much uranium turns to lead. Then they find out how long ago the mineral formed. This process can be used to to date fossils as old as 4 billion years old.

  38. I claim that you can tell how old or young a fossil is by where the layers are.
    The older fossils are gonna be closer to the bottom and the younger layers are gonna be closer to the top. It also depends on where the part of the organism is dead because some different places could be older than others. It might also depend oh how many organisms of that same species there is in that area and some species could have arrived at different times than other species would have. It could also depend on the minerals because of the radioactive atoms that are in the mineral but scientists also can just say that this rock is relevant to that other rock in age but what they need to do is use a machine called the spectrometer that is able to tell how old a rock actually is be seeing how much duranium is in a rock.

  39. I claim that the oldest rocks will be the farthest down. The newest would be the closest to the top. I think the oldest ones are on bottom because over thousands of years dirt and rock build up and fossils can buried.

    • I claim that the oldest fossils will be the farthest down in the earths crust. The newest would be the farthest to the top of the earth. I think the newest ones would be on top because the rocks and dirt build up over time, and the oldest farthest down. Scientist can also date fossils by the radioactivity, some rocks contain uranium atoms and sometimes they explode into lead, so scientist can found out about how old the fossil is.

      * in my first post I meant fossils instead of rocks.

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