The Active Earth
National Park Service Mission
...to conserve the scenery and the natural and historic objects and the wild life therein and to provide for the enjoyment of the same in such manner and by such means as will leave them unimpaired for the enjoyment of future generations.
Black Canyon of the Gunnison National Park and Curecanti National Recreation Area Outreach Education is committed to: Creating an awareness and fostering an appreciation for the mission of the National Park Service and the natural, cultural, and historic resources of Curecanti National Recreation Area and Black Canyon of the Gunnison National Park.
EDUCATION LESSON PLAN
Title: The Active Earth
Grade level: Eighth Grade
Time length: 4 hours
Subject areas: Science, language arts, math
Teacher: Two NPS Education Specialists
Theme: The geology of the Gunnison area illustrates the ever-changing nature of the earth.
NPS focus: Public Law 39-535 (Organic Act),
Environmental concepts: Everything must fit how and where it lives (adaptation).
Environmental learning hierarchy: Problem solving processes, decision making procedures
Materials: PowerPoint projector, introductory NPS CD, Active Earth CD, extention cord; jar filled with water and sand, silly putty; examples of rock: igneous, sedimentary, metamorphic, breccia, welded tuff; Dillon Pinnacles worksheets; (for optional activities) era cards, one set of laminated cards bearing the definitions of Cenozoic, Mesozoic, Paleozoic, and Precambrian time eras; 4 time line starters: one piece of paper with a black arrow drawn on it to be the basis of the time line (0 years to billion years), 4 red, orange, green, and blue markers corresponding to colors on laminated era cards; 16 concentration cards; surveyors tape; clue cards; pencils.
I. INSTRUCTIONAL OUTCOMES
Comprehension: The students will be able to describe three earth building forces and three weathering forces, giving examples of each. The students will be able to describe one way scientists learn about how the earth formed and how it is changing.
II. ANTICIPATORY SET
Start with the introductory National Park Service PowerPoint presentation, then segue into the following:
The Black Canyon is a spectacular geologic formation. Within Curecanti NRA, there are also rock formations that are unique. Today we’ll be visiting one of the most dramatic formations, called Dillon Pinnacles. Before we head out, let’s talk a bit about geology, to make sure that you’ll understand everything that you see during the hike.
Geology. When I was your age, I thought geology was incredibly boring, something that didn’t have anything to do with my life. I thought dinosaurs were pretty neat and I knew that fossils could tell us a lot about the dinosaurs, but that was about the end of my interest in geology. But then I slowly began to realize that most everything around me had to do with geology, or the study of the earth and rocks. For instance, the buses that you rode in today are made of metals, which come from minerals. The fuel that propelled the bus comes from petroleum, a product of the earth. The lead of a pencil is graphite, a mineral. The plastic chairs you’re sitting on are petroleum products. Little by little, I became interested in geology, and I was pretty excited to move to the Gunnison area, because geology is so visible around here. Within a half an hour’s drive from here, we can find Precambrian rock, or the rock that existed on this earth before any living thing came into being. We can see the Dakota sandstone that formed at the bottom of an ancient inland sea that used to cover the state of Colorado. We can see the Morrison Formation, the land that the dinosaurs used to walk on when this area was covered in jungles. The geology is found in layers, and the layers can tell us an amazing story about the past, just like the chapters in a book.
Let’s imagine that the history of the Earth could fit into a book that has 1000 pages. Each page would represent 5 million years. The first 880 pages would represent the Precambrian era. During the Precambiran, there was no life on planet Earth. No plants, animals, not even tiny living bacteria. The rock walls of the Black Canyon formed during the Precambrian era. In this diagram, where is the oldest rock, near the bottom or the rim of the canyon? At the bottom, correct, because it was deposited first, and then other rock layers formed on top of it. The next era was called the Paleozoic, which means “first life”. The Paleozoic era fills pages 881-955 of our 1000 page book. During this time, Colorado was covered by an ocean that no longer exists. We know for a fact that this ocean existed here because paleontologists have found indicative fossils of fish and amphibians across the state. Next, the Mesozoic era occurred, covering pages 956-986. During this time, the dinosaurs came into being, and then completely disappeared, birds evolved from reptiles, and the first mammals developed. During the walk to Dillon Pinnacles, we’ll point out the three layers of rock that were deposited during the Mesozoic era. Now let’s continue with the final era, that of the Cenozoic. The Cenozoic era began on page 987 and it continues today. Dillon Pinnacles formed during the Cenozoic era. Does anyone know on what page human beings came into existence? On page 1000, in the very last sentence. That puts into perspective how new we are to the Earth, and how old the Earth really is.
III. TEACHING PROCEDURE/METHODOLOGY
"Who here speaks a language other than English? Have any of you ever opened a book written in another language? You know there's a story or some information in there, but, unless you know the language, it is silent. Look around you, anywhere on the planet, but especially here in the Gunnison country/Western Slope. There is a fascinating story simply screaming from the landscape around you, but unless you know the language of geology, you won't know the story. What are some of the words we need to know in this new language? Geo-logy. "Logy" means "the study of." Compare to Zoo-logy, Bio-logy." Demonstrate the main geological forces that shaped the Gunnison Basin, DEPOSITION, DEFORMATION, and EROSION. Ask students to: shake a jar filled with water and sand then set it on the table to represent deposition; pull and break silly putty representing deformation.
Now I'd like to show you a presentation about geology and specifically the geology of Curecanti.
Active Earth Slideshow
Slide 1: The geology of Colorado makes it one of the most beautiful places in the United States. What makes this state so unusual and also so beautiful is the geology we see around us every day, including the mountains, the canyons, and the rocks. Today you are going to learn how this land came to be as it is today.
Slide 2: We’ll talk a little about the canyons, a little about the mountains, and a little about the rocks. First, let's talk about the kinds of rocks that are found on this earth of ours. Geologists classify rocks into three different and distinct groups.
Slide 3: Igneous rocks are formed when magma or lava from a volcano cools and hardens.
Slide 4: Over time, the hardened lava or magma might look like this example of pink igneous rock called pegmatite, which, when it was in a liquid form, squeezed itself up into a crack in the metamorphic rock all around it.
Slide 5: The second type of rock is sedimentary. Sedimentary rocks are composed of minerals or organic matter deposited by ice, water or air, and compressed together. Within sedimentary rock, you can sometimes see layers, like in this picture. About 90% of geologic history is interpreted through sedimentary rocks, partially because that’s where we can find dinosaur fossils. Dinosaur fossils have been excavated from Curecanti NRA.
Slide 6: The final type of rock is metamorphic. Metamorphic rocks are formed when the other two types of rocks are altered by the action of heat, pressure, or chemically active fluids.
Slide 7: Now that we’ve briefly reviewed the three categories of rocks, let’s discuss the three processes that affect rocks. These processes are called deposition, deformation, and erosion. Let's look at the process called deposition. Nearly all deposition occurs when materials sift down through fluids, and deposit themselves in horizontal layers.
Slide 8: An example of sedimentary deposition which occurred horizontally is the Grand Canyon in Arizona. Not all deposition occurs this way.
Slide 9: Another way that deposition occurs is through volcanic activity, which plays an important part in the geology of this area. Molten rock oozes from cracks in the earth and is deposited, forming hard, basaltic materials.
Slide 10: The top of Grand Mesa is an example of this type of deposition.
Slide 11: Sometimes explosive volcanic material, varying in size from large boulders to fine microscopic grains, is ejected into the atmosphere and settles into formations such as the West Elk Breccia found at the Dillon Pinnacles. If the material is very fine and well sorted as it is ejected, the resultant material will be fine unconsolidated cinder.
Slide 12: If, however, the material is still incandescent or white hot, then it will be welded together as the welded tuff found on the mesa tops of this area. Welded tuff is a very durable, tough rock layer.
Slide 13: When you look at the formation in this picture, notice that the layers are not horizontal. If they were originally deposited horizontally, then some process has altered them. That process is called deformation. Rocks, in many ways, act like silly putty. Remember when we experimented with the silly putty, we could bend and stretch it? Rock bends and stretches, too.
Slide 14: Here we see a fold or monocline. The pressure was slow and steady and the rock was bent and took the form seen here.
Slide 15: However, when the silly putty was moved quickly, it broke. Rocks also break when moved quickly, in a process called faulting. If you look very closely, you might see that at one time this section and this one were together, but a rapid pressure was applied to the rock and the rock could not respond, therefore it broke. Earthquakes sometimes occur on fault lines.
Slide 16: We have seen examples of deposition, and deformation. If these were the only active processes, the earth would have changed very little since its beginning. The process that alters and changes our planet the most is erosion, which takes place after the deposition and the deformation.
Erosion is defined as the wearing away of land by the action of natural forces, such as wind and water.
Slide 17: The most active weathering agent is water. All rain is acid! One of the components of the atmosphere is a gas called carbon dioxide. As water falls from clouds, it absorbs some of the carbon dioxide, forming a weak acid called carbonic acid. This is the same acid found in soda pop, the thing that makes your tongue tingle when you drink Coca-Cola, Dr. Pepper or 7-up. This acid begins to work on the earth's materials by dissolving the cementing agents, which hold the rocks together.
Slide 18: This cave was formed through the process of erosion. At first, water dissolved some of the cementing agents holding the sand particles together, in a process called chemical weathering. Once the cavity became enlarged, the sand grains fell to the bottom and the wind began to swirl them around, further enlarging the opening, through mechanical weathering.
Slide 19: Here we see a very primitive plant-like organism called lichen. Lichen is actually two organisms, fungus and algae, living together in a symbiotic relationship, meaning that they each benefit the other in some way. The fungus provides a place for the algae to grow, or shelter, and the algae provides food for the fungus, since the fungus is not able to photosynthesize. In this process, chemicals are released from the lichen, and the chemicals begin to break down the rocks that the lichen is growing upon.
Slide 20: Eventually, soil is formed, allowing more advanced plant life to grow. Tree seeds fall into cracks, germinate and grow. As the tree grows, the roots expand, not only from growth, but also by swelling from the water they absorb and the rock is deteriorated even more.
Slide 21: Ice also plays an important role in the erosion process. Water trickles down into the cracks of rocks and upon freezing it expands, wedging the rocks apart. As long as the water stays frozen, the rocks stay where they are, but in the spring when melting occurs, the rocks fall from the cliffs. This is why most rockslides in Colorado happen in the spring.
Slide 22: The sun also acts as a weathering agent. Rock begins to expand as it is heated by the sun. Rock, however, is not a good conductor of heat. That means that the rock below the surface does not expand, because the heat from the sun cannot penetrate its surface. This change in temperature causes the rock to shatter, much like a glass taken out of a freezer and filled with hot water.
These processes, deposition, deformation, and erosion are what shape the land and give it character which we see and appreciate.
Slide 23: Let's take a pictorial trip through the different formations we can find here at Curecanti National Recreation Area. We'll start at the bottom, since those rocks are the oldest. The oldest formation is called Precambrian, and is dated between 1.4 and 1.7 billion years old. This formation is best exposed at Morrow Point Lake, and there we find some of the best Precambrian geology in the entire United States, if not the world. Many of the structures are so spectacular they have been given names.
Slide 24: One example is the Curecanti Needle, whose shape was so dramatic that it was chosen as a symbol to represent the Denver and Rio Grand railroad, the scenic line of the world. The Precambrian rocks in this area are predominantly gneiss, quartz monzonite, and granite type rocks. They are very hard and weather resistant, so they don't break apart or erode very easily. This explains why the canyons are so deep and narrow. The rock is so strong that only water is powerful enough to carve a channel through it.
Slide 25: The next formation that we'll see on our way up is the Junction Creek member of the Wanakah formation, which is about 150 million years old. This formation is found West of the Blue Mesa Dam, along both highways 50 and 92. This material represents a sand dune deposit and shows the crossbedding associated with dunes, particularly in the red-orange layer.
Slide 26: Next, we find the Morrison formation. The bright Easter egg colors denote different depositional environments, which is typical of an area where streams meander back and forth along a coastal plain. This formation contains most of the dinosaur bones found in the Western United States, and most of the Uranium deposits. Actually, the fossils of a sauropod dinosaur were discovered in the Morrison formation in Curecanti, right above the shoreline of Blue Mesa Reservoir.
Slide 27: Above the Morrison is the Dakota sandstone, a fine to very fine-grained sandstone, much like beach sand.
Slide 28: In fact it is beach sand. During cretaceous time, about 100 million years ago, a shallow sea covered this area. The Dakota sandstone was the beach at its edge as it came on the land.
Slide 29: Directly above the Dakota formation is Mancos shale, which is the material deposited at the bottom of the Cretaceous sea. This shale is up to 5,000 feet thick near Grand Junction, but 250 to 400 feet thick near Blue Mesa Reservoir.
Slide 30: Resting uncomfortably upon the Mancos is the most spectacular formation in this area, the West Elk Breccia. The Dillon Pinnacles best represent the breccia formation. West Elk Breccia is the remnants of multi sized volcanic materials from the West Elk volcanic activity, which was washed to its present location by extensive rain and melted snow. This breccia is not well cemented, and therefore erodes into very unusual shapes.
Slide 31: (Dillon Pinnacles)
Slide 32: The last rock type found is the welded tuffs of the mesa tops. Ash from the volcanic activity in the San Juan Mountains to the south fell upon the land. The ash was still white hot when it landed, and welded itself together to form a very weather resistant cap. As long as this cap remains intact, the mesa will remain high and only mildly weathered.
Slide 33: In the next hundreds of years, this landscape may continue to look much like it does today. But if we were to come back in a million years, the effects of erosion and possibly volcanic activity will probably have changed it so dramatically that we wouldn't even recognize it.
You have now been introduced to the geologic processes and the formations here at Curecanti National Recreation Area. Later today we’ll be walking the trail to Dillon Pinnacles. On your way, try to find examples of deposition, deformation, and erosion
(On their way out to the bus, have each student pick up a copy of the worksheets. Drive a separate car to the Pinnacles trailhead, and meet the bus there. Divide into groups and allow a distance between groups on the trail. Communicate by radio and agree when to stop for lunch. After lunch, students can complete worksheets and ranger can lead a discussion. On the walk back, all students should stay with their assigned group.)
IV. CHECK FOR STUDENT UNDERSTANDING
V. GUIDED PRACTICE
Along the trail, point out examples of each type of rock, deposition, deformation, and erosion. Talk about the forces of erosion, and what the Dillon Pinnacles will look like in 100 or one million years.
Awareness of Change
VI. INDEPENDENT PRACTICE
IX. REFERENCES CITED
X. RELATED INTERNET SITES
Did You Know?
The Black Canyon contains some of the oldest exposed rock on Earth. Precambrian, or “basement” rock, is nearly 2 billion years old.