Stratigraphy

Megan Blanchard

What is Stratigraphy?

• Stratigraphy is the study of the layers of sedimentary rock of the earth

• Sedimentary rock can be found at the surface of the earth or deep down in the layers of the earth

• The layers that are deep down at the bottom of the earth were once the surface of the earth but have now been covered by more and more layers sedimentary rock

Layers of Rock

• Each layer of sedimentary rock builds on a layer that already existed

• For example we have a pile of books. What happens when we stack one on top of another?

• Which layer is the youngest? Which layer is the oldest? How do we know this?

What did we learn?• Law of Superposition: In a pile of sedimentary rocks, the layer on

the top is always the youngest and the layer on the bottom is always the oldest-unless it has been moved

• Law of Original Horizontality: the layers of sedimentary rock are usually spread horizontally unless the earth’s movement causes them to move and shift differently which can cause some layers to be tilted

• Core: A rock core is shaped like a cylinder and is taken from the earthby a large drill-This can be done onland or in the ocean

http://www.msnucleus.org

Activity

• What would happen if we could not see these layers? Let’s find out!

• Wait until I give the signal to get into groups of 5-6, once you are in a group have one person gather up materials: 1 plastic cup with tape (do not remove tape), playdoh, 2-3 straws, 1 worksheet

Activity

• Have one person from the group be the recorder for the worksheet

• Make predictions as a group of what you might see

• Complete the steps on the worksheet to create your layers using the playdoh and take the core samples

• Next observe the core samples and Fill out your worksheet as a group