Fossils and carbon dating

William Smith was one of the most important scientists from this time who helped to develop knowledge of the succession of different fossils by studying their distribution through the sequence of sedimentary rocks in southern England.It wasn't until well into the 20th century that enough information had accumulated about the rate of radioactive decay that the age of rocks and fossils in number of years could be determined through radiometric age dating.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. This is an informational tour in which students gain a basic understanding of geologic time, the evidence for events in Earth’s history, relative and absolute dating techniques, and the significance of the Geologic Time Scale.­ ­You probably have seen or read news stories about fascinating ancient artifacts.How do scientists know how old an object or human remains are?

This element is locked in tiny zircons within the granite. While it stays within the zircon for a period of time, being a very small atom, helium escapes the zircon within a few thousand years.At an ar­chaeological dig, a piece of wooden tool is unearthed and the archaeologist finds it to be 5,000 years old.A child mummy is found high in the Andes and the archaeologist says the child lived more than 2,000 years ago.It is used in dating things such as bone, cloth, wood and plant fibers that were created in the relatively recent past by human activities. Students not only want to know how old a fossil is, but they want to know how that age was determined.