1Daily Warm-Up Exercises Day 44 Why is mountain sand usually angular and poorly-sorted? The grains that make up mountain sand have not been carried far from where they formed. They’re angular because they weren’t carried far, so the sharp edges didn’t have time to get worn off. They’re poorly sorted because grains of all sizes were deposited at the same time.

2 Correlate Grand Canyon Layers (Part 2, steps 7-13) Investigation 3 Grand Canyon Rocks

3 Review Study Sites Which site is closer to Lee's Ferry, North Canyon or Nankoweap? North Canyon How far apart are the two sites? 32 miles At which site is the river elevation higher? North Canyon

4 Cut Out the Rock Layers  We're going to arrange our rock columns to more closely match their actual positions.  Cut out both columns along the dashed lines.  Place the columns on a blank sheet of paper.  Work together to decide how best to position the columns on the page.

5 Discuss Layer Positions How should the columns be positioned?  They should be separated to show that there are 32 miles between them.  The North Canyon column should be higher on the page to show that the river elevation is higher.  The rock layers that match should be straight across from each other.

6 Line Up the Rock Layers  Position your columns as described on the previous slide and tape them in place.  Draw horizontal lines to connect the tops and bottoms of matching layers.  Draw slanted lines to connect the top and bottom of the river.  Label a place on the river that would be the 36-mile mark.

7 Define "Rock Layer"  A rock layer is a flat deposit of rock that extends over a large area.  Some rock layers are thick, and some are thin.  The Colorado River cut through the rock layers in the Grand Canyon, just like cutting through a cake and exposing the layers.

8 Fill in the Rock Layers  Geologists use symbols to show different kinds of rock.  Use these symbols to fill in the layers on your page.

9 Correlation  Correlate is a word that means to find a relationship or connection between rock layers from two or more locations.  You just correlated rock layers from two sites at the Grand Canyon.  Answer the Grand Canyon Correlation Questions on page 15.