Name______________________________________________ Date_______________ Period_________
Pancakes and Relative Dating
Standard 4a. Describe and apply principles of relative age (superposition, original horizontality, cross-cutting relations, and
original lateral continuity) and describe how unconformities form.
1. Look around. You want to make pancakes. Do you expect pancakes to magically appear? No, really how are you going to make
them?
2. Because you have probably already made pancakes before at some point in your life, do you think that the way you will make
them today will be similar to the way you have made them before? NOTE- ignore the fact that you might have used a frying pan
instead of a griddle or a different kind of batter, etc. I am talking about at the most basic level. Do you think rocks are formed
today the same way they were in the past?
3. Use page 185 in your book to find a word that explains that the way we make pancakes today is very similar to the way
pancakes were made in the past and define it.
Now that you have proven your great intelligence, you are ready to cook. Follow these directions:
1. Get a griddle and preheat it to 350 degrees.
6. You turn pancakes with a spatula (egg flipper) when you
2. It will be hot; don’t touch it.
see little air bubbles in the CENTER of the pancake.
3. Start mixing up the batter for about 12 pancakes (recipes
7. When the pancakes are done, stack them vertically on
for 10-15 are fine).
top on top of one another list the following picture. Your
4. Right before you are ready to cook some, spray the
stack should be six pancakes high.
griddle lightly with cooking spray.
8. Turn off your griddle; you will make the rest of your
5. Spoon out the batter (you will need a spoon for this )
pancakes in a minute.
so that you fill the most surface of your griddle with about 6
pancakes.
4. The pancakes represent sedimentary rock strata. Define strata (186).
5. Number the pancakes in the picture above from 1-4 with the oldest being #1 and the youngest being #4. This is as easy as it
sounds. What general statement can you make about the age of pancakes on a plate in terms of how they compare to the
pancake above and below them?
6. Give an example of a situation where this wouldn’t be true.
7. What you have just described in #5 and #6 is the basis for the law of superposition. Define this term.
8. I know your pancakes look good (hopefully), but let’s remember that they are actually sedimentary rocks. Look at your “rocks”
on the plate. Are they lying vertically or horizontally? If you leave them alone, do you think they would stay that way?
9. What you have just described is the principle of original horizontality. Define this term.
10. Go ahead and start making your other six pancakes while answering #11. These will be your “new” pancakes.
11. Imagine you started eating the pancakes off the top of your stack or stopped making them for a while and then came back
tomorrow and made more to add to your stack. Using page 189, what would this be similar to? Define this word.
12. On a new plate, pile up a mound of peanut butter 1 cm high (about the width of your pinkie from nail to fingerprint) and
about the width of a pancake. Get a plastic knife and use the serrated (jagged) edge to scrape off (erode) thin layers of peanut
butter off the top for about one minute. Now, put two of your new pancakes (sedimentary strata) on the top of the peanut
butter. If the peanut butter represented igneous or metamorphic rock (have no layers like peanut butter), what type of
unconformity did you just make?
Draw and label the parts of a nonconformity below:
13. Take three “old” pancakes and cut them in half. You can eat the left-side half of them. Using the right-side half, tilt them
vertically like in the picture of angular unconformities, and then stack the remaining four “new” pancakes on top. Draw and label
the parts of an angular unconformity below:
14. Using the three remaining “old” pancakes, steal and eat the one in the middle. How is this like a disconformity?
Draw and label the parts of a disconformity below.
15. Pick up your four “new” pancakes off of the angular unconformity. Do NOT eat them. You can eat the tilted strata (little
halves underneath). Put your four pancakes on a plate. Cut them at angle like in the picture on page 190. Which is older, the
pancakes or the cut?
16. What do the pancakes represent? What does the cut represent?
17. Make an igneous intrusion by poking a hole that runs through your “rock layers” and pouring syrup into it. You can make the
hole at any angle or direction. Which is older, the rock or the igneous intrusion?
18. Define the law of crosscutting relationships.
19. While using the illustration from page 190 to order the following from oldest to youngest- the igneous intrusion, layer A,
layer B, layer C, layer D, and the fault.
The principle of lateral continuity states that layers of sediment initially extend laterally (side to side) in all directions; in other
words, they are laterally continuous. As a result, rocks that are otherwise similar, but are now separated by a valley or other
erosional feature, can be assumed to be the same rock layer.
Layers of sediment do not extend indefinitely; rather, as the amount of sediment lessens away from the source, the layer of that
material will become thinner.
20. Draw an example of what you think this might look like. Use a valley to separate the layers. Use colors to show that they
layers that are separated are still the same rock formation. Hint- think of the Grand Canyon.
21. How could you do this with pancakes?
22. How is the relative age of a rock different from its absolute age? Create an example of a relative age and an absolute age for
a rock.