Standard 3

Objective 3: Describe how rock and fossil evidence is used to infer Earth’s history. a) Describe how the deposition of rock materials produces layering of sedimentary rocks over time. b) Identify the assumptions scientists make to determine relative ages of rock layers. c) Explain why some sedimentary rock layers may not always appear with youngest rock on top and older rocks below (i.e., folding, faulting). d) Research how fossils show evidence of the changing surface of the Earth. e) Research how fossils show evidence of the changing surface of the Earth

Deposition Over time sediments that were eroded get deposited somewhere else like the sand on this beach.

Relative Dating With Rock Layers Superposition As layers accumulate through time, older layers are buried beneath younger layers. If geologists can determine which way was originally “up” in a stack of layers, they can put those strata in the correct historical order. -the-Past/Sci-Media/Animations-and- Interactives/Relative-rock-layers

Layers aren’t always in order Why might they not be in order? Draw pictures of the following ●Faulting ●Folding ●Erosion ●Redeposition (sediments redeposit after erosion.)

Folding

Faulting

Correlation of Strata and Index Fossils Lateral Continuity: Scientists can relate layers at one location to layers at another. They use rock type and index fossils to see what layers are the same age.

Fossil Evidence How do fossils show evidence of the changing surface of the Earth? Watch the video

3:3 Quiz 1.Why do we have layers of rock? 2.Why aren’t those layers always in order? 3.How can we use layers to know the relative age of something? 4.Name 4 things fossils can tell us.