Geology of Table Rock - 7th - Post-site Activities

Geology of Table Rock - 7th - Post-site Activities/Teacher Led

Grade Level: 7
Content Area: Science
Time to Complete: 45 minutes
Title of Lesson: Compare and Contrast Sediment Samples

South Carolina State Standards Addressed:

I.A.1.a.1.	Observe patterns of objects and events.
I.A.1.a.2.	Distinguish between qualitative and quantitative observations.
I.A.1.b.1.	Arrange data in sequential order.
I.A.1.d.1.	Make inferences based on observations.
I.A.1.e.1.	Predict the results of actions based on patterns in data and experiences.
III.A.1.a.	Distinguish among weathering, erosion, and deposition.
III.A.1.b.	Examine how physical weathering and chemical weathering breaks rocks into fragments.
III.A.1.c.	Investigate and examine how the Earth's surface is constantly changing by weathering, erosion, deposition and human impact.
III.A.1.e.	Relate the fertility of floodplains to the deposition of sediments.
III.A.2.b.	Analyze soil properties that can be observed (soil profile, composition, texture, particle size) and can be measured (permeability, temperature, pH, moisture) to predict soil quality.
III.A.2.c.	Explain why soil (sediments) can be a major pollutant of streams.
III.A.2.d.	Evaluate ways in which human activities have effected soil and the measures taken to control the impact (silt fences, ground cover, farming, land use, nutrient balance).

Program Description:

Students will perform a hands-on activity analyzing texture, composition, and effects of weathering on three different sediment samples gathered from the Table Rock field trip.

Focus Questions For Students:

1.	Where does sediment come from?
2.	What does the location of a sediment deposit tell us about this history?
3.	How does sediment (rock/mineral particles) change with time?

Culminating Assessment:

Have students write a short story about the life and travels of a grain of sand that broke off Table Rock Mountain and ended up in Pinnacle Lake.

Materials/Equipment/Resources:

(Per Class)
	sediment samples from Carrick Creek (2)
	sediment sample from swimming beach
(Per Group)
	hand lens
	tweezers
	data table
	vocabulary
	sediment sample questions

Teacher Preparation:

1.	Read background information.
2.	Be prepared to answer questions about the composition and texture of sediment.
3.	Be sure all sediment samples are completely dry. They may be dried in an oven or on a hotplate on low setting or even by sitting in a sunny spot where air can circulate.

Background Information:

   The Blue Ridge Mountain Region, located in the northwestern corner of South Carolina, is the only truly mountainous region in our state. The Blue Ridge is characterized by drastic elevation changes and high relief. Streams in the Blue Ridge generally flow in narrow valleys and are usually small and rocky with clear, cold water and many rapids and waterfalls. Landslides and other mass movement of rock and soil are common occurrences in the mountains. The amount of water flowing in these streams varies greatly depending on the amount of precipitation that has fallen recently in the local area. It is this fast flowing water that can round and sort rock and mineral particles (sediment). Along the flatter sections of streams small floodplain areas occur. Only these bottomland areas contain soil rich enough for farming.
   Blue Ridge rocks are composed of various types of igneous and metamorphic rock, especially granite-gneiss and amphibolite. Many Blue Ridge rocks started out deep underground as large igneous intrusions of granite that were eventually uplifted and metamorphosed. During this metamorphism, high temperature and pressure totally recrystallized the minerals present. The dominant minerals now present in rock in this area are quartz and feldspar (light color) and amphibole (dark color). As the overlying rock and soil was slowly removed by erosion, the granite-gneiss rose closer to the surface and began to expand and crack. The mountains as we know them today took form as the resistant granite-gneiss rose while less resistant rock was eroded away.
   In addition to being altered by metamorphism, the rock in the Blue Ridge Region has been severely fractured and folded by tectonic activity. The fractures in particular create zones of weakness and provide preferred pathways for stream erosion and chemical weathering. In general, the higher elevated section of Table Rock Mountain is mostly granite-gneiss and is very resistant to erosion. Lower elevations are generally underlain by the less resistant amphibolite. The relative positioning of these two main rock types, resistant and non-resistant, determines the occurrence of waterfalls, rapids, and water slides within the area. Vegetation grows more readily on the easily decomposed amphibolite areas. For more information refer to the background information from SC MAPS Teaching Manual, 2000 Edition, pages 2-2 through 2-4.

Procedures:

1.	As a class, discuss what is known about the three sediment samples and their surroundings.
2.	Place the students in groups of 3 or 4.
3.	Give each group about 2g (or 1 ml) of each Carrick Creek sediment sample and the swimming beach sediment sample.
4.	Students will study each sample for evidence of physical and chemical weathering, size differences among the particles, rounded vs. non-rounded particles, light colored vs. dark colored particles, and organic matter present. Record the information for each sample in the data table.
5.	Students should use the tweezers and hand lens to separate each sample into its major parts. Use the hand lens to get a closer look at your samples.
6.	After the samples are studied and the data recorded, answer the sediment sample questions.