Curriculum Notebook - Grade 9
Redwood in Marcel's Forest

Interpretive Stops

 1.  Along Aptos Creek
 2.  Fern Grotto
 3.  Twisted Grove
 4.  Geologic Foundation
 5.  Redwoods and Associates
 6.  Magnificent Old Growth
 7.  Fairy Ring in the Making
 8.  Granary, Stump, and Burl
 9.  The Pourroy Garden
10. The Little Slide
11. Smiley Face Stump
12. Big "Round"
13. Goosepen Tree
14. The "Advocate Tree"
15. The Ravine
16. Pourroy's Picnic Area

Additional Information

 Animals of Marcel's Forest

 

 


Shake the Rocks

Grade 9
Investigation and Experimentation

Analyze the locations, sequences, or time intervals that are characteristic of natural phenomena.

  Objectives

1. To model stream erosion.

2. To discover how much mass is worn away during 15-20 minutes of shaking.

  Concept Background

Since the uplift of the Santa Cruz Mountains in the late Pliocene, Aptos Creek has eroded soil and rock over thousands of years. As evidenced by the amount of sediment in the creek, layers of rock under Marcel's Forest are composed of soft siltstones and sandstones. Clear-cut logging in the upper portion of the park during the late 19th-century also added sedimentation to the creek.

The waters of Aptos Creek continue to erode soil and rock. What will this creek look like a 100 or 1000 years from now?

  Materials

1. Use the Pourroy's Picnic Area, Stop 16, which has a large level area on the embankment of Aptos Creek with a picnic table.

2. Marble chips (buy marbles at the local five-and-dime store and then hammer into smaller sizes)

3. Balance

4. Jar

5. Sieve

6. Water (can be taken from Aptos Creek)

7. Large radio with music tapes

  Instructions

45 Minutes

Students weigh out 100 grams of marble chips, put them in a jar and fill it 1/3 full of water. They will shake the rocks for 15-20 minutes to music. (Key: Music should have a beat, preferably Latin -- Macarena, etc.) At the end of the 15 to 20-minute period, students determine the mass of the marble chips and see how much mass was lost. Students then answer follow-up questions:

1. Can you determine how much mass would be worn away in a million years?

2. Has the water changed color? Why?

If marble chips are used:

1. The water changes color;

2. Students can easily figure out how much mass would be lost in a million years, depending on whether the stream was "fast" or "slow" (i.e., how hard they shook the rocks);

3. Why water is the major agent of erosion;

4. How differing rock hardnesses would produce different amounts of erosion (and explain waterfalls like Yosemite, Yellowstone, etc.).

This activity was remembered by my students when they were seniors! Of all my lab activities in the years I was teaching, this was the best.

Modified from AskERIC Lesson Plan #AELP-GLG0057, Author: Mark Schoenfeld, Lakeland C.S.D., Shrub Oak, New York (retired)
Reminders
Glossary
Curriculum Notebook
Materials Drawer
California Science Education Website
 
Weathered Sandstone Found Along the Creek
"Weathered Sandstone" found along Aptos Creek

 

Diorite
Granodiorite, a variety of granite which probably washed down from an exposure at Bridge Creek. This type of granite, part of the basement layer of rock called the "Salinian Block," is also seen in the Olive Springs quarry. Those rocks are 121 million years old. (Clark)
 
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