While it may seem obvious today, most people at the time did not believe that fossils were once part of living creatures.The reason was that the fossils of clams, snails, and other marine animals were found in tall mountains, miles from any ocean. Some religious writers believed that the shells were washed up during the Biblical flood.When geologists study layers of rocks, they get a glimpse of the past.Determining the precise way that sedimentary rocks have layered throughout time gives them insight into how natural events have occurred.It only sequences the age of things or determines if something is older or younger than other things.Some types of relative dating techniques include climate chronology, dendrochronology, ice core sampling, stratigraphy, and seriation.In this activity, students begin a sequencing activity with familiar items letters written on cards.Once they are able to manipulate the cards into the correct sequence, they are asked to do a similar sequencing activity using fossil pictures printed on "rock layer" cards.
To understand stratigraphy and relative dating, four basic principles must be mastered.
Seriation uses the assumption that once a tool was developed, its use would become more widespread.
Stratigraphy uses the assumption that higher layers or strata were laid down after lower layers.
The study of fossils and the exploration of what they tell scientists about past climates and environments on Earth can be an interesting study for students of all ages.
Teaching about Earth's history is a challenge for all teachers.