Relative Dating Relative Dating is a process of putting things in a "correct order" based on experience. It doesn’t give an exact age but a relative (or comparison) age. This means that you know which events came first, but not the exact time when they happened. Rocks form in layers. The layers at the bottom are the oldest and each successive layer will be younger. This is called superposition. Superposition is the principle that says younger rocks lie above older rocks in an undisturbed sequence.

Age of fossils Scientists use the fossils of animals to help determine relative age. Certain groups of fossil animals and plants occur in the geologic record in a specific order. If a scientist finds one of those fossils they can then assume the age of the rock based on the age of the fossil.

Limestone formed first Then sandstone Then Shale To interpret Earth history, a diagram called a stratigraphy is sometimes used. Take a look at this one and see if you can see the order that events happened. Use this key to identify the rocks: Conglomerate Sandstone Limestone Shale Limestone formed first Then sandstone Then Shale 4. An earthquake faulted the rocks. The earthquake fault occurred last because the rocks had to all be there before they could be offset.

Let’s try a harder one. There are 10 steps, including the events that happened to the rocks. Do you see the unconformity? Conglomerate Sandstone Limestone Shale unconformity They are conglomerate, sandstone, limestone, sandstone, shale, erosion, limestone, sandstone, shale, erosion.

Limestone, sandstone, igneous (volcano) Igneous rocks “intrude” into other rocks. Because they are hot, they affect the rocks that are near them. What type of rocks are heated but not melted? Metamorphic Look at this stratigraphy and see if you can list the steps. The dark lines show contact metamorphism. Conglomerate Sandstone Limestone Shale Igneous Limestone, sandstone, igneous (volcano)

Number the pictures from one to five with one being the oldest and five being the youngest.

1.Is Rock layer "A" younger or older than the other rocks? A. Younger because it intruded into the other layers. B. Older because it layers B and C are above it. C. Younger because its lava D. Older because its intruded inside the rock layers.

2.Is the fault (dotted line labeled "L") older or younger than layer D? A. Younger because fault L occurred before layer D B. Older because layers E thru J are older then layer D. C. Younger because it is above layer J D. Older because it is above all the layers.

3. List the rock layers in order from oldest to youngest 3.List the rock layers in order from oldest to youngest. (include the lines "K" and "L"). A. b,c,d,k,j,i,h,a,g,f,e,L B. L,e,f,g,a,h,i,j,k,.,d,c,b C. e, f,g,h,i,j,L, k, d,c,b D. D,k,j,i, h, a, g, e, L, f, b, c

4. Which layer is probably the youngest? A. Layer V B. Layer III C. Layer II D. Layer I

5. What could have caused the rock layers A through F to slant up instead of laying horizontally? A. Volcano eruption B. A big giant C. Earthquake D. gravity

6. What does the dark, heavy line below layer H represent? A. Fault line B. Erosion C. Pipelines D. Fossil layer

7. What has caused the left section of this cross-section to slide down or the right side to shift up? A. volcanoes B. Earthquakes C. Gravity D. None of the above

8. Is layer H younger or older than the erosion line? A. Younger B. Older

9. Is layer D younger or older than layer I? A. Younger B. Older C. same age