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Starter 03/13/13. Why do sedimentary rocks form layers?. Directions
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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 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
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.
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. These are igneous intrusions.
Where is the intrusive igneous rock? It has GLUED the other rock together!
Put the layers in order from OLDEST to YOUNGEST A B C F E D H G
Put the layers in order from OLDEST to YOUNGEST A B I C H D G F E
1. 2. 3. 4. 5. 6. 7. 8. R X D K B G
Starter 03/15/13 How are fossils formed? Please put your homework on your desk
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… Phoberomyspattersoni, 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
0 mya 160 mya 250 mya 8 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…