Watch this 25 minute video on "relative age dating" to understand what to do here. A bonus from this video is the discussion given on unconformities, which might help you for your video project due this week. I strongly suggest that you look at that assignment and its related videos before starting this discussion assignment.
1) In the figure above, order the lettered items from oldest to youngest. Some units are marked with the same letter more than once. This is to show that they are the same rock unit. So there are 4 areas marked with "S" but that means they are the same rock--all connected even though they are separated by other things. Everyone in the group needs to work together on the answer to this. Consider answering questions 2-6 below the figure before you attempt the sequence if you are stuck. Also, the puzzle has 2 possible solutions that are reasonable. Can you determine both of them?
2) Are there any unconformities in the figure? If so, specify what letter corresponds to any unconformity present and name the type of unconformity.
3) What is B?
4) Why is it important that M is labelled as "regionally metamorphosed rock?" What does that imply about its age? Where does regionally metamorphosed rock form? How did it get positioned at the top of this sequence?
5) What kind of rock (igneous, sedimentary, or metamorphic) must X and V be? Explain your reasoning.
6) What is J?
Next Question
7) You are walking in the desert and come upon a hill with many horizontal (flat-lying) layers of sedimentary rock. As you walk up the hill, you discover fossils in some of the layers. You excitedly start to grab the fossils, shoving them into your pockets and backpack. When you get home, you look each of them up and discover their name and the geological time period in which they lived. You jot this information down in a list as you look at each fossil. The list is shown below. You don’t remember what order on the hill you collected the samples, but given what you have learned about them, rearrange the list to show the order in which you must have found the fossils as you walked up the hill. Write your results in the table below in the column on the right hand side. Use the geologic time scale to help you figure this out.
The List
Tiktaalik (an early amphibian)—Devonian
Paraceratherium—Paleogene
Gogia (an eocrinoid, related to sea urchins and seastars)—Ordovician
Stromatolite (a photosynthetic microbial colony)—PreCambrian
Euparkaria (a reptile)—Triassic
The Order of Layers on the Hill
The Layers in which the Fossils Must Occur
Top layer (5)
Layer 4
Layer 3
Layer 2
Bottom layer (1)