Only questions posted as Public are visible on our website. Make sure to notice that the time scale on the right of the figure is a section being blown up of the time scale on the left side of the figure.
Also be sure to look at the title of each column — Eon, Epoch, Period, etc. All the information you will need for this assignment is in our textbook and lecture material, therefore there is no need for any additional sources. The attachment have the page Figure 9. A time scale label example is thousands of years ago, days old, minutes old, billions of years ago, etc. Geologic Time Scale Practice: What is the age label for the geologic time scale we are using refer to the far right column? This is what MYA stands for.
The numerical age range of the Mesozoic Era is million years ago to What is the numerical age range of the Cambrian Period? What is the name of the Eon with the numerical age range of 2, — million years ago?
What is the name of the Era that covers the time age range from What is the oldest numerical age listed on this time scale? What is the numerical age range of the Holocene Epoch? What is the main element that the tree is made of? This is one element from the Chemical Periodic Table, An example of an element is H for hydrogen or Sn for tin — now which element is the main one in trees? Check out the periodic table here http: Now that you know what numerical age range the log is from, and what material the log is made of — take these two pieces of information to decide on one type of numerical dating technique that would work to date the log.
Give two reasons why you chose the numerical dating technique that you did in question 7 for the log. What is the numerical age range of the Permian Period? What type of rock is a Felsic Volcanic Unit — it is one of the three rock types from the rock cycle we reviewed in week 3? Now that you know what numerical age range of the Permian Period and what type of rock the Felsic Volcanic Unit is,— take these two pieces of information to decide on one type of numerical dating technique that would work for this rock in this scenario.
Give two reasons why you chose the numerical dating technique that you did in question 11 for the rock. As shown in Figure 9. Another glance at the time scale reveals that eons are divided into eras. As the names imply, these eras are bounded by profound worldwide changes in life-forms.
Numerical dates were added long after the time scale was established using relative dating techniques. The dates on this time scale are those currently accepted by the International Commission on Stratigraphy ICS in The color scheme used on this chart was selected because it is similar to that used by the ICS.
Each era of the Phanerozoic eon is further divided into time units known as periods. The Paleozoic has seven, and the Mesozoic and Cenozoic each have three. Each of these periods is characterized by a somewhat less profound change in life-forms as compared with the eras. Each of the periods is divided into still smaller units called epochs. As you can see in Figure 9. The epochs of other periods usually are simply termed early, middle, and late. Precambrian Time Notice that the detailed portion of the geologic time scale does not begin until about million years ago, the date for the beginning of the Cambrian period.
It is also common for this vast expanse of time to simply be referred to as the Precambrian. Although it represents about 88 percent of Earth history, the Precambrian is not divided into nearly as many smaller time units as the Phanerozoic eon. Why is the huge expanse of Precambrian time not divided into numerous eras, periods, and epochs? The reason is that Precambrian history is not known in great enough detail. The further back we go, the less that is known. Certainly more data and information exist about the past 10 years than for the first decade of the twentieth century; the events of the nineteenth century have been documented much better than the events of the first century C.
So it is with Earth history. The more recent past has the freshest, least disturbed, and most observable record. The further back in time a geologist goes, the more fragmented the record and clues become. Other reasons to explain our lack of a detailed time scale for this vast segment of Earth history include: Prior to the Cambrian, simple life-forms such as algae, bacteria, fungi, and worms predominated.
All of these organisms lack hard parts, an important condition favoring preservation. For this reason, there is only a meager Precambrian fossil record. Many exposures of Precambrian rocks have been studied in some detail, but correlation can be difficult when fossils are lacking. Because Precambrian rocks are very old, most have been subjected to a great many changes.
Much of the Precambrian rock record is composed of highly distorted metamorphic rocks. This makes it difficult to interpret past environments because many of the clues present in the original sedimentary rocks have been destroyed. UCLA Thank you once again for extending your trust, and, please let me know if there is anything you feel needs to be addressed.
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