geologic time and rock amp mineral identification guide adapted from home science tools 2008b

Geologic Time (Radiometric Dating Techniques): Answer the questions below.

  1. What unstable isotope would be best to refine the date of bones found in a cave hearth built by humans between 30,000 and 50,000 years ago?
  2. We find samples of an igneous rock demonstrate it has been through 4 half-lives. The test element has a half-life of 150 million years. How old is the rock?
  3. Argue for or against the following: A stone tool fashioned from a chunk of obsidian yields a date of 5,000,000 years old, therefore, the tool was made by a human 5,000,000 years ago.
  4. You are trying to figure out the age of what is thought to be a very old fossil with a volcanic ash layer immediately above the fossil. We know the fossil is at least more than 250 million years old. Should we use carbon 14 to date the fossil, or uranium 238 to date the volcanic ash layer, and why?
  5. If the parent isotope starts with 100 grams, but your samples yield only 12.5 grams of the parent isotope, how many half-lives have passed?