Earth History Exam 2-3 Study Guide

Name______Science 8.____Date______

Earth History Exam 2-3 Study Guide

The test is on everything from Investigations 2 & 3

• Earth History Packet (pages 1-17) – binder page 38
• Notes

Part 1: Define the following terms:

1. Grand Canyon– largest canyon in the United States; located in northwest Arizona
2. John Wesley Powell–first scientific explorer of the Colorado River and the Grand Canyon
3. Rock sample–a small representative piece of rock that represents the properties of the entire layer
4. Elevation–vertical distance above sea level
5. Layer–a flat deposit of rock
6. Correlation–to find a relationship or connection (between rock layers)
7. Formation–a rock layer composed of more than one kind of rock, but the kinds and sequence of rocks can be recognized from one place to another
8. Rock Column– the sequence of rocks seen in a particular area
9. Plateau–a large, nearly level area of land that has been uplifted or elevated above the surrounding area
10. Butte–Do not need to know – I should have deleted this!!!

Part 2: Sedimentary Rock Types

1. Shale–a rock with a smooth texture that does not contain calcite (no fizz)
2. Sandstone–a rock made out of sand particles cemented together; rough texture
3. Limestone– a rock that contains calcite (fizzes when in contact with acid)

20. If you are observing the three types of sedimentary rocks, how can you tell the difference betweensandstone and shale? Neither of these fizz with acid. Because of this, look at their texture. Sandstone has a rough and gritty texture. Shale has a smooth texture.

21. If you are observing the three types of sedimentary rocks, how can you tell the difference betweensandstone and limestone?Limestone contains calcite. Therefore, it will fizz when acid is placed onto it. Limestone is the only rock we studied that will fizz when you put acid on it.

1. Why do limestone rocks fizz when HCl acid is placed on them? Explain the reaction occurring.

Acid + Calcite  Carbon Dioxide + Water.

When you place acid on a rock with calcite, the two will react. The result is a fizzing and bubbling which is the release of carbon dioxide.

Part 3: Differential Erosion

23. Differential Erosion–harder rocks erode more slowly than softer rocks

24. Which two sedimentary rocks are harder and erode more slowly? Sandstone & Limestone

25. Which sedimentary rock is softer and erodes easily/quickly?Shale

26. If you are looking at a rock formation, how can you tell just by looking at it which rocks are sandstone/limestone or which ones are shale? In other words, what types of shapes do limestone, sandstone, and shale form when they erode?

1. By shape. Shale layers will form a crumbling slope. Limestone and sandstone layers will form cliffs.

2. By how much of each layer is left. Shale is soft and erodes quickly so a shale layer will always be smaller in size than a sandstone or limestone layer that eroded for the same amount of time.

Part 4: Rock Correlation Questions – Using the provided chart, answer the following questions.

1. How far apart are Canyons A and B? 87 miles – 50 miles = 37 miles
2. Which direction does the river flow? A to B or B to A? How do you know?

A  B, rivers always flow from high elevation to low elevation. Canyon A is higher than Canyon B.

1. If you were paddling down the river at mile 87, what type of rock would you see?

Muav Limestone

1. If you were on the river at mile 50, and drilled a hole beneath the Bright Angel Shale, what type of rock would you expect the find first? What evidence do you have to support your inference?

Coconino Sandstone – that is the layer under Bright Angel Shale at Canyon B, so we may infer that it is the same at Canyon A. Remember that rock layers extend for hundreds of miles which is why we can make this guess.

1. Why do we see different rocks exposed at the two locations?

The river at Canyon B is 600 feet lower than it is at Canyon A. Thus, the river at Canyon B has exposed 600 extra feet of rock. Those rocks are still present at Canyon A, but the river has not eroded all the way down to them yet.