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Geologists use two techniques to date rock layers. The first technique is called "relative dating." If one layer of rock lies above another, we can regard the upper layer as younger, particularly when the layers are relatively horizontal and do not show faulting. When one finds layers at an angle, especially at a sharp angle, one can regard the formation as due to shifts in the earth that occurred after the layers were deposited. When one sees that one kind of rock cuts across layers of other kinds of rock, one can regard the intruding rock material as younger. Rock material enclosed in another kind of rock material can be regarded as older than the enclosing material.
Relative dating is basically studying the layers of rock exposed at a site and making common-sense inferences about how the layers could have been formed so as to produce the layering one sees.
Relative dating does not allow one to assign a numerical age to a rock formation.
Radiometric dating does allow estimation of a numerical age for a rock formation. To carry out radiometric dating, one studies the quantities of specific isotopes of radioactive elements relative to the specific isotopes of the elements into which the radioactive elements decay. For example, uranium 235 decays into lead 207. We know the half-life of uranium 235. So, if we find that the amount of U-235 is equal to the amount of lead 207, we can regard the rock as being about as old as the half-life of uranium, which we know to be on the order of 700 million years. In other words, when the rock we're studying solidified, the uranium was captured within it. The uranium then turned into lead at a known rate, which also remained captured in the solid rock until we came along and examined it. Knowing the rate allows us to calculate the length of time the uranium has been sitting in the rock.
Needless to say, the actual process involved in applying this concept has its complexities. However, this is the basis of the procedure. By examining large numbers of rock formations, using both relative and radiometric dating, we can work out the patterns that govern the formation of rock layers. By comparing large numbers of sites to each other, we can learn to see that the rocks at one site have the same characteristics as the rocks at another site. Just as we learn to estimate the ages of people by indirect means, such as skin texture, hair color, posture, voice, and even attitude, we learn to recognize that at a given site, the rock layers show the same characteristics as other rock layers of known age. We can thereby infer the age of rock layers at a site where something prevents us from analyzing the rocks directly.
Fossils found in rocks can be useful for determining the age of rocks. From a variety of sources quite independent of rock geology, we know how old some fossils are. When we find such fossils in rock, we can use the fossils as a clue to the age of the rock. In like manner, when we find fossils of unknown age embedded in rock of known age, we can infer the age of the fossils. Of course, as anyone with common sense would realize, we cannot determine both the age of a fossil and the age of the rock around it from each other. We have to compare both specimens to other specimens of known age, and apply, if possible, techniques such as radiometric dating to determine the age of the material we're examining.
What else can I help you with?
An understanding of which of these best enabled scientists to determine the approximate ages of fossils?
The understanding of radioactive decay, specifically carbon dating and other radiometric dating methods, has enabled scientists to determine the approximate ages of fossils by measuring the decay of isotopes within the fossils. This process allows scientists to estimate the age of fossils based on the ratio of isotopes present in the sample.
In sedimentation what order does the layers goes?
In sedimentation, the layers are arranged in chronological order with the oldest layer at the bottom and the youngest layer at the top. This is known as the Law of Superposition in geology, which helps scientists determine the relative ages of different rock layers.
How do scientist determine the ages of rocks?
They can use either radiometric dating or magnetostratigraphy.
What law do scientists apply to determine relative ages of rocks when the find faults or intrusions?
Scientists use the principle of cross-cutting relationships to determine the relative ages of rocks when they find faults or intrusions. This principle states that the rock being cut must be older than the geological event cutting through it (like a fault or intrusion). By analyzing the sequence of events and their relative ages, scientists can piece together the geological history of a region.
What is the law of superposition and how does it help scientists learn about earth's past?
The law of superposition states that in a sequence of undisturbed rock layers, the oldest layers are at the bottom and the youngest layers are at the top. By studying the order of rock layers and the fossils within them, scientists can determine the relative ages of the rocks and reconstruct the Earth's past environments and history.
An understanding of which of these best enabled scientists to determine the approximate ages of fossils?
The understanding of radioactive decay, specifically carbon dating and other radiometric dating methods, has enabled scientists to determine the approximate ages of fossils by measuring the decay of isotopes within the fossils. This process allows scientists to estimate the age of fossils based on the ratio of isotopes present in the sample.
In sedimentation what order does the layers goes?
In sedimentation, the layers are arranged in chronological order with the oldest layer at the bottom and the youngest layer at the top. This is known as the Law of Superposition in geology, which helps scientists determine the relative ages of different rock layers.
Where are the oldest organisms located in the rock layer?
The oldest organisms can generally be found in the lower layers of rock, as these layers were formed earlier than the upper layers. By examining the relative positions of different rock layers, scientists can determine the ages of the organisms found within them.
How do scientist determine the ages of rocks?
They can use either radiometric dating or magnetostratigraphy.
How do scientists determine the age of a fossilized human bone?
The teeth: wear and tear - How much grinding has occurred? The presense of wisdom teeth indidcates certain ages. Also the sutures of the skull close at various ages.
Which is an example of relative dating?
One example of relative dating is studying the layers of rock in a particular area. By analyzing the sequence of rock layers and the fossils within them, scientists can determine the relative ages of the rocks and the fossils they contain.
Can fossils be used to determine the relative ages of rocks layers?
fossils can be used to determine the relative age of rock layer by using the classification of fossils to find the relative ages of rocks in which fossils are found. :] hoped i helped you out.
How can fossills be used to determine the relative ages of rock layers?
fossils can be used to determine the relative age of rock layer by using the classification of fossils to find the relative ages of rocks in which fossils are found. :] hoped i helped you out.
What law do scientists apply to determine relative ages of rocks when the find faults or intrusions?
Scientists use the principle of cross-cutting relationships to determine the relative ages of rocks when they find faults or intrusions. This principle states that the rock being cut must be older than the geological event cutting through it (like a fault or intrusion). By analyzing the sequence of events and their relative ages, scientists can piece together the geological history of a region.
What is the law of superposition and how does it help scientists learn about earth's past?
The law of superposition states that in a sequence of undisturbed rock layers, the oldest layers are at the bottom and the youngest layers are at the top. By studying the order of rock layers and the fossils within them, scientists can determine the relative ages of the rocks and reconstruct the Earth's past environments and history.
How are the laws of superposition and crosscutting relationships used to determine the age of rocks?
They are used to determine the relative ages of rocks by stating that younger rocks lie above older rocks, and that rocks that cut through a layer are younger than the existing layer.
How are the laws of superposition and crosscutting relationship used to determine the relative age of rocks?
They are used to determine the relative ages of rocks by stating that younger rocks lie above older rocks, and that rocks that cut through a layer are younger than the existing layer.
