A relative age dating activity
A process called relative-age dating helps scientists determine how old these rock layers are.By radiometric dating they determined the granite to be 85 million years old and the lava flow 80 million years old, thus shale layer 3 must be between 80 and 85 million years old.However, "relative" dating or time can be an easy concept for students to learn.In this activity, students begin a sequencing activity with familiar items letters written on cards.The limestone is younger than 80 million years old.This activity was selected for the On the Cutting Edge Exemplary Teaching Collection Resources in this top level collection a) must have scored Exemplary or Very Good in all five review categories, and must also rate as “Exemplary” in at least three of the five categories.Once students begin to grasp "relative" dating, they can extend their knowledge of geologic time by exploring radiometric dating and developing a timeline of Earth's history.Much of the information presented in this section is based upon the Stuiver and Polach (1977) paper "Discussion: Reporting of C14 data". 1890 wood was chosen as the radiocarbon standard because it was growing prior to the fossil fuel effects of the industrial revolution.
This quick assessment allows me to verify student understanding of the concept of superposition. The use of Silly Bandz was great and the students were really able to differentiate between absolute and relative.
You can get an idea of the relationship between C14 and age at the Carbon Dating calculator page. 1950 was chosen for no particular reason other than to honour the publication of the first radiocarbon dates calculated in December 1949 (Taylor, 19).
Ninety-five percent of the activity of Oxalic Acid from the year 1950 is equal to the measured activity of the absolute radiocarbon standard which is 1890 wood.
A copy of this paper may be found in the Radiocarbon Home Page The radiocarbon age of a sample is obtained by measurement of the residual radioactivity. T (National Institute of Standards and Technology; Gaithersburg, Maryland, USA) Oxalic Acid I (C). The activity of 1890 wood is corrected for radioactive decay to 1950.
This is calculated through careful measurement of the residual activity (per gram C) remaining in a sample whose age is Unknown, compared with the activity present in Modern and Background samples. Thus 1950, is year 0 BP by convention in radiocarbon dating and is deemed to be the 'present'.The class was able to identify the culprits, as well as indicate how the law of superposition applied. The idea was easily modeled using the nonsense words and the fossil cards.