Table of Contents
- 1 Why is a uranium isotope often used rather than C in radiometric dating to determine the age of Earth?
- 2 How are index fossils used to determine the age of fossils or rock layers quizlet?
- 3 What types of evidence of ancient life can be preserved as fossils?
- 4 Why is uranium 238 used to date rocks?
- 5 Why are index fossils used to date rock layers?
- 6 Why are index fossils used as guides to determine the age of rocks?
- 7 Why are stromatolites so important?
Why is a uranium isotope often used rather than C in radiometric dating to determine the age of Earth?
in radiometric dating, why is a uranium isotope often used instead of carbon-14 to determine the age of the earth? Because carbon-14 only has a half-life of 5730 years, while any uranium isotope has a half-life of around 4 billion years.
How are index fossils used to determine the age of fossils or rock layers quizlet?
Index fossils are fossils of organisms that existed only during specific spans of time over large geographic areas. Using index fossils for age estimates of rock layers is not a new idea. It organized Earth’s history by major changes or events that have occurred, using evidence from the fossil and geologic records.
What types of evidence of ancient life can be preserved as fossils?
what types of evidence of ancient life can be preserved as fossils? bones, shells, tissue (rarely), nests, footprints, plants, insects, etc can all be fossilized.
Why do you think that people have discovered relatively few fossils from the early history of life on Earth?
Considering that millions of species have lived on Earth, why are there relatively few fossils? Because Earth constantly undergoes erosion and rock recycling, rocks on Earth do not remain in their original state. They did not have the right conditions for fossils to be formed.
Why is uranium used to date rocks?
Uranium-lead dating can be used to find the age of a uranium-containing mineral. Uranium-238 decays to lead-206, and uranium-235 decays to lead-207. The two uranium isotopes decay at different rates, and this helps make uranium-lead dating one of the most reliable methods because it provides a built-in cross-check.
Why is uranium 238 used to date rocks?
The long half-life of uranium-238 makes it possible to date only the oldest rocks. This method is not reliable for measuring the age of rocks less than 10 million years old because so little of the uranium will have decayed within that period of time.
Why are index fossils used to date rock layers?
Certain fossils, called index fossils, help geologists match rock layers. To be useful as an index fossil, a fossil must be widely distributed and represent a type of organism that existed for a brief time period. Index fossils are useful because they tell the relative ages of the rock layers in which they occur.
Why are index fossils used as guides to determine the age of rocks?
Why are index fossils used as guides to determine the age of rocks? Each index fossil lived during a specific geologic time period. All index fossils lived during all the periods of geologic time. The rock layers below were dated using the radioactive decay method.
What role do fossils play in making the geologic time scale?
Fossils are fundamental to the geologic time scale. The names of most of the eons and eras end in zoic, because these time intervals are often recognized on the basis of animal life. Rocks formed during the Proterozoic Eon may have fossils of relative simple organisms, such as bacteria, algae, and wormlike animals.
Can the shelf and rocks be considered evidence that a continent was drifted How?
Evidence for Continental Drift. Besides the way the continents fit together, Wegener and his supporters collected a great deal of evidence for the continental drift hypothesis. Wegener said the rocks had formed side-by-side and that the land had since moved apart.
Why are stromatolites so important?
The real significance of stromatolites is that they are the earliest fossil evidence of life on Earth. Early cyanobacteria in stromatolites are thought to be responsible for increasing the amount of oxygen in the primeval Earth’s atmosphere through their continuing photosynthesis.