Half life dating fossils

05-Jul-2014 07:05 by 4 Comments

Half life dating fossils - Adulat wabcam live to baich

This activity on determining age of rocks and fossils is intended for 8th or 9th grade students.It is estimated to require four hours of class time, including approximately one hour total of occasional instruction and explanation from the teacher and two hours of group (team) and individual activities by the students, plus one hour of discussion among students within the working groups.

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Geologists call this the principle of lateral continuity.

To do this we need to know the amount of radioactive material remaining in the object.

Students not only want to know how old a fossil is, but they want to know how that age was determined.

As long as you follow these four steps you will always be able to accurately determine the age of a rock or fossil.

The first thing we want to know to find the age of an object is to figure out how many half-lives have passed.

The sediment of this area was laid down after ammonite A appeared 199 million years ago, and before ammonite B became extinct 195 million years ago.

This narrows the date of the delta beds to the four million years between these dates.

By comparing the amount of C14 in an object to the amount of N14 in it we can determine how long it has been decaying for, and therefore when the organism died. Through decay Uranium-238 turns into stable Lead-206.

Because its half-life is so long it is useful for dating the oldest rocks on Earth, but not very reliable for rocks under 10 million years old. This is ten times the age of the Earth, so very little Rubidium has decayed at all.

A fossil will always be younger than fossils in the beds beneath it and this is called the principle of superposition.

In an undisturbed sequence of rocks, such as in a cliff face, it is easy to get a rough idea of the ages of the individual strata – the oldest lies at the bottom and the youngest lies at the top.

This is because new sediments are always laid down on top of sediments that have already been deposited.