# Line graphs and radiometric dating

24.05.2017

## line graphs and radiometric dating

Below are three isocrons for 3 different rocks datijg the Rb-Sr method described in the introduction. This graph illustrates two major points regarding radiometric dating: From this data you will determine how many half-lives the isotope grahps gone through, and therefore the age of the rock. Download No category Graphing Half Life WS. Number of parent isotope atoms. Modified from an activity from SERC Teach the Earth. Isotopic analyses have been carried out on minerals separated from the three crystalline rocks A, B, and C. Calculate the number of half-lives: As scientists, your job is to count the **line graphs and radiometric dating** of parent and daughter isotope atoms in each bag. K and the rise in the fraction of Line graphs and radiometric dating raciometric time. If it is not a valid method, explain why. But if you know the half-life as well as the number of atoms of both isotopes, you can calculate the age in years—an absolute age. Do you think scientists can use more than one type of isotope to date the same rock or fossil? Why would they want to? Dt is the number of daughter atoms datinf. You learned the principle of radiometric dating:

Radiometric dating problem set. Radiometric Dating of Earth Materials. Online Isochron Dating Set. Consider the plots below, showing the decay in the fraction of. K and the rise in the fraction of A over time. The half life for K40 is 1. Answer the following questions: Number of parent isotope atoms. Number of daughter isotope atoms. In this activity you will use your knowledge of radioactive decay and half-life properties to figure out the line graphs and radiometric dating daging five different "fossils" at different stations *line graphs and radiometric dating* the xnd.

The bags dzting the fossil and the beads inside represent some of the millions of atoms that make them up. As scientists, your job is to count the number of parent and daughter isotope atoms in each bag. From this data you will determine how many half-lives the isotope has gone through, and therefore the age of the rock. You will rotate in groups from station to station until you have figured out the age of all five fossils.

Fossil 5 - yellow are parent Th, brown are daughter Pb Calculate the number of half-lives: This ratio gives you the percentage of parent isotope atoms left after radioactive decay. Now use a half-life graph of predicted decay rates to determine the number of half-lives the isotope has gone through based on this percentage see graph.

Finally, to figure out the age of the fossil, take the number of half-lives, and multiply it by the length of the half-life. Rank the fossils from oldest to youngest. Which two were very close in age? In this activity, which "fossil" came from the time just after the formation of the earth? Do you think any real fossils could come from that time? Radiometic or why not?

Why do you think there were lots of beads of other colors in the bag besides the ones you were counting? Do you think line graphs and radiometric dating can use more than one type of isotope to date the same rock or fossil? Why would they want to? If you wanted to date a sample that you estimated to be about 1 million years old, which isotope would radioemtric use to date it, Uranium or Thorium ?

How Fast is a Liquid Cooled? Use the data and graphs on this spreadsheet to complete these problems: What is the temperature of the liquid after 4 minutes of cooling? What is the temperature of the liquid after 10 minutes of cooling? At what times will the liquid cool to the following temperatures? Some important concepts are emphasized: First, for each parent isotope decay, one daughter isotope is created. Rather, the number of decays over a given time period changes with the number of parents present simple example: Half-life is the time required for half of the parents to decay to a stable daughter.

Given these basic points you can follow the construction of a Parent and Daughter vs. Time graph second tab at the bottom of the spreadsheet. This graph illustrates two major points regarding radiometric line graphs and radiometric dating First, the point of intersection between the parent and daughter curves both have equal numbers of atoms illustrates the concept of a half-life. Second, this exercise graphically shows the change in the Parent-Daughter ratio with time. With every half-life, there will be fewer parent atoms and more daughters atoms.

Do you think all rocks be dated by radiometric methods? Enter your answers in the chart. Explain the method you used to determine the age of the mineral that contains a particular radioactive isotope parent daughter pair in the chart above. Using Radiometric Dating to Help Determine the Geologic History of an Area. You will calculate the absolute ages of three different vating shown on the geologic cross-section below.

These units are A—the basaltic dike, B—the granite, and C—the folded metamorphic rock ignore the two sandstone layers above the angular unconformity for this exercise. Isotopic analyses have been carried out on minerals separated from the three crystalline rocks A, B, and C. These data are listed below. To calculate the ages of the rocks, you will need to understand the principles of radiometric dating that you learned in class.

In this problem, we will be using the K-Ar potassium-argon system; potassium has a half-life of 1. Results of Isotopic Analyses: You learned the principle of radiometric dating: The decay rate is stated in terms of half-lives: As the rock ages, the amount of the parent isotope will decrease and the amount of the daughter isotope will increase geometrically not linearly. Graphs of radioactive decay clearly show this exponential decay. To determine the age of an unknown rock, you need to measure the number of **line graphs and radiometric dating** and daughter atoms in a sample this data is given to you in the table above.

The ratio of the daughter atoms to the parent atoms is proportional to the age. But if you know the half-life as well as the number of atoms line graphs and radiometric dating both isotopes, you can calculate the age oine years—an absolute age. You need to gaphs the following formula: Po is the number of parent atoms originally present when the rock formed. Pt is the number line graphs and radiometric dating parent atoms today.

Dt is the number of daughter atoms today. Obviously, the total of the parent and daughter atoms today is equal to the number of parent atoms when the rock formed, since each daughter atom came from a parent atom. This ratio is the percent of parent atoms remaining in the system today, and is directly related to the number of half-lives that have transpired since the rock crystallized from magma. If you know the number of half-lives, you can calculate the age of the rock.

Use the formula above and the graph below to graphz the questions: What is the absolute age of the basaltic dike, unit A? What is the relative age Eon use the geologic time scale in rsdiometric textbook to determine this? What is the absolute age of the granite, *line graphs and radiometric dating* B? What is the absolute age of the folded metamorphic rock, unit C?

Modified from an activity from SERC Teach the Earth. Click here to get to the online absolute dating site.

Isotopes Frequently Used in Radiometric Dating. Stable Daughter. Half Life Values You should have two lines on one graph. Data Analysis Questions: To be. based on radiometric dating. • “radioactivity” Examine the graph that plots the abundance of . in a sample. the 4 colored lines represent 4 different isotopes. (in half-lives). Graph 2— Radiometric Dating Game parent isotope abundance graph. 12 m . to the x-axis until it intersects the diagonal line on the graph. That radiometric dating practice problems with answers creative comes meeting. that some people Line Graphs and Radiometric Dating.