Why do sedimentary rocks form layers? Starter 03/13/13 Why do sedimentary rocks form layers?

Directions 1. Take a glass and fill it 1/2 full of water. This is the “lake”. Add a layer of one of the colors of sand or gravel. To model a dead organism, drop one of the sea shells in it next to the side of the glass so you can see it. It is now a fossil. 2. A flood fills the lake with new sediments. Add another color of sand or gravel to the “lake”. Add another sea shell for the new fossil. 3. A wind storm carries a large amount of dust into the lake. Add another layer of sediment and a fossil. 4. Draw and color a picture of your glass and label the fossils (give them a name of your choice) Then answer the questions.

Relative Dating

Relative Dating Relative dating is a way to determine the order in which something happened It is based on two assumptions: That events in the past occurred in the same way that they do today Sedimentary rocks are stacked on Earth’s surface with the oldest layers on the bottom

Which layer is oldest?

Relative Dating Flat layers of sedimentary rock do not stay flat for very long. These are some of the changes that can be made to flat layers of sedimentary rock…

1. Layers of Rock can be FOLDED! Pressure from inside Earth pushes outward, toward the surface.

2. Layers of Rock can be moved by FAULTS

3. Layers of Rock can be eroded by wind or water.

See how the upper layers have eroded so that this older white band is at the surface?

4. Layers of Rock can be added to by sedimentation or deposition.

New Layers Folding

5. Layers of rock can have magma seep into them 5. Layers of rock can have magma seep into them. These are igneous intrusions.

Where is the igneous intrusion?

Can you see where the magma spread out from the vein?

Where is the intrusive igneous rock? It has GLUED the other rock together!

Put the layers in order from OLDEST to YOUNGEST B C F E D H G

Put the layers in order from OLDEST to YOUNGEST B I C H D G F E

G B K D X R 1. 2. 3. 4. 5. 6. 7. 8.

Please put your homework on your desk Starter 03/15/13 How are fossils formed? Please put your homework on your desk

Horses evolved about 55 million years ago. Meet the… Horses evolved about 55 million years ago.

Meet these… Dinosaurs lived from about 230 million years ago, to 65 million years ago…that’s nearly 160 MILLION YEARS!!!

Meet the… Phoberomys pattersoni, or Ratzilla, lived in Venuzula about 8 million years ago

Meet the… Trilobites appeared very early in Earth’s history but disappeared around 250 million years ago, when dinosaurs appeared on Earth

In which layer would we find each of these animals? 0 mya 160 mya 8 mya 250 mya In which layer would we find each of these animals?

Fossil formation Fossil formation involves deposition AND erosion! Step 1: Animal or Plant dies and sinks to the bottom of a body of water.

Fossil formation Step 2: The animal gets covered in sediment (the process of deposition!)

Fossil Formation Step 2: The animal gets covered in sediment layers(the process of deposition!)

Fossil Formation Step 3: The water evaporates and the animal’s body decays, leaving the skeleton. (The minerals in the rock around and above the animal make the skeleton harder…)

Fossil Formation How bones are made stronger by rock minerals…

Fossil Formation Step 4: The pressure from the rock layers SQUISHES the skeleton and makes an indentation in the rock.

Fossil Formation Step 5: Erosion brings the skeleton closer to the surface so that we can find the fossil.

Fossil formation And what we see is this… MOLD CAST

Fossil Formation MOLD CAST

Fossil Formation MOLD CAST

Fossil Formation MOLD CAST

Fossil Formation Some fossils are found as casts. Others are found as molds. Which is which in this picture? Cast Mold

Fossil Formation CAST MOLD

What is this?

Fossils show Changes over Time… Smaller eyebrow bones Thinner upper jaw

Fossils show Changes over Time… Upper skull slopes backward Upper jaw gets smaller

Fossils show Changes over Time… Skull is round instead of oval shaped Cheek bones point up instead of out

Fossils show Changes over Time… Eyebrow bone nearly disappears Upper jaw is almost flat, instead of sticking out

Fossils show Changes over Time… Skull is round on top instead of flat Eyebrow bone blends into skull Lower jaw is less thick

Fossils show Changes over Time… How might humans change in the future? What will our fossils look like in 100,000,000 years?