The most obvious feature of sedimentary rock is its layering.
This feature is produced by changes in deposition over time.
This means that a quartz sandstone deposited 500 million years ago will look very similar to a quartz sandstone deposited 50 years ago.
Making this processes even more difficult is the fact that due to plate tectonics some rock layers have been uplifted into mountains and eroded while others have subsided to form basins and be buried by younger sediments.
Sequencing the rock layers will show students how paleontologists use fossils to give relative dates to rock strata.
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.
To deal with many of these problems geologists utilize two types of geologic time: relative time and absolute time.
Information about one of the rock layers will appear – drag the hammer and drop it onto the layer you think is being described. This layer formed on top of earlier rocks after they were tilted and eroded away.
Carry on and place all the hammers on the correct layers.
A fossil can be studied to determine what kind of organism it represents, how the organism lived, and how it was preserved.
However, by itself a fossil has little meaning unless it is placed within some context.