Field Trips
- Grade Level:
- Upper Elementary: Third Grade through Fifth Grade
- Subject:
- Science
- State Standards:
- Strand 5.1: Characteristics and Interactions of Earth’s Systems.
Standard 5.1.1 Analyze and interpret data
Standard 5.1.3 Ask questions to plan and carry out investigations
Standard 5.1.4 Develop a model to describe interactions between Earth’s systems
At a field trip site, students examine a limestone layer to find fossils and make clay models to reenact movement along a local fault. Students hike through three rock layers to observe how the characteristics of rocks produce arches.
Essential Question: How do geologic processes change earth’s physical features?
Utah State Science Core Curriculum Topic:
Strand 5.1: Characteristics and Interactions of Earth’s Systems.
Earth’s major systems are the geosphere, the hydrosphere, the atmosphere, and the biosphere. These systems interact in multiple ways. Weathering and erosion are examples of interactions between Earth’s systems.
Standard 5.1.1 Analyze and interpret data to describe patterns of Earth's features.
Standard 5.1.3 Ask questions to plan and carry out investigations that provide evidence for the effects of weathering and the rate of erosion on the geosphere.
Standard 5.1.4 Develop a model to describe interactions between Earth’s systems including the geosphere, biosphere, hydrosphere, and/or atmosphere. Emphasize interactions between only two systems at a time.
Background
The rock layers and fault exposed at the entrance to Arches National Park are of textbook quality. The layers are easy to see; they have different colors and different compositions because they were formed in different environments.
By examining rocks close-up, we learn about the ancient environments in which the sediments of the rock layers were deposited. Most mudstones and siltstones formed in low-gradient streams or tidal-flat environments. Some sandstones were deposited in steeper streams or on beaches. Sandstones made up of very rounded sand grains that are all the same size (well-rounded and well-sorted, in geological terms) indicate aeolian or windblown deposition in a relatively dry environment. Limestones usually indicate a marine environment, and many contain fossils. (A few thin limestone layers in the Moab area were deposited in freshwater lakes.)
Any plant or animal that dies on earth can be fossilized if the conditions are correct. In order for a creature, or evidence of a creature, to be preserved as a fossil, the creature is not broken down or disintegrated before it is buried in sediment. Many fossils are formed at the bottom of oceans, where deposition is continuously occurring and dead organisms are quickly buried. This, and the hard shells many marine creatures have, is why most fossils are of marine organisms. Fossils of land-dwelling creatures are less common. The Hermosa layer, found in the bottom of Bloody Mary Wash, contains an abundance of fossils. This limestone layer was deposited in an offshore marine environment about 300 million years ago.
The Hermosa layer contains fossils of tropical sea creatures:
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Crinoids- are still alive today but are called sealilies. They look like a flower but are animals related to sea stars and sea urchins. They wave their feather parts in the water to catch their plankton dinner. The part we see as a fossil is the stem; the feather part rots away. As a fossil, they resemble stacks of pennies or fruit loop necklaces.
- Brachiopods- look like an oyster or a clam because they have hinged shells. However, they are only distantly related to oysters. Brachiopods trap food by filter feeding.
- Bryozoa- Like brachiopods, bryozoa are also filter feeders. They looked like seaweed but were really teeny tiny animals that lived together in colonies like coral. When fossilized, they resemble dots, and each dot is an individual creature.
- Horn coral- were shaped like a cone or horn and probably had stinging tentacles to capture their prey. Even though they were very common during the Permian, they all went extinct.
- Trilobites- were very common. Some paleontologists consider trilobites the most successful type of early animal because there were so many kinds. They are not common at Arches in our fossil record, however. Trilobites have been extinct since the end of the Permian.
A geologic fault is a break or fracture in the rock, along where displacement of the strata has occurred. Most faults form during earthquakes or volcanic activity associated with the shifting of tectonic plates. In southeastern Utah, however, much faulting is associated with an unusual phenomenon, the movement of underground salt layers. Faults are commonly buried by sediment and difficult to see, but the Moab fault is spectacularly exposed at the field trip site. The Hermosa Limestone has been shifted 2,500 feet upward on the west side of the fault, past seven other rock layers. It is now on the same level as the Carmel Formation (Dewey Bridge Member) east of the fault.
The rock formations seen at Park Ave have been carved principally from 4 Jurassic-aged strata. These are, from bottom to top: Navajo Sandstone, the Dewey Bridge Member of the Carmel Formation, the Slick Rock Member of Entrada Sandstone, and the Moab Member of the Curtis Formation. These rock formations are the product of several depositional environments, such as dunes, beach, and tidal flat deposits.
Arches National Park’s erosional landscape of valleys, towers, fins, canyons, pinnacles, and arches began to form about 10 million years ago. That’s relatively young in geologic terms; the rock layers in the park were deposited roughly 300 million to 150 million years ago. These landforms can be attributed to deposition, deformation (folding and fracturing), and erosion that began in the late Pennsylvania Period (over 300 MYA) and continues to shape the landscape today.
Based on the definition of an arch as an opening at least three feet in one direction, over 2,000 named arches can be found in Arches National Park, most within Entrada Sandstone. Water is the main culprit in arch formation. Rainwater is usually slightly acidic, which weakens the cement between grains in the sandstone. The process of ice wedging involves water freezing (expanding) and thawing (contracting) in pores and cracks. This process is key in breaking apart sand grains, especially because of the large temperature fluctuations of the high desert climate. In addition to water, wind and gravity aid the process of erosion by removing the weathered parts of rocks. Arches can be classified by their shapes; categories include free-standing arches, cliff-wall arches, and jug-handle arches. Natural bridges, unlike arches, are formed by flowing streams.
Weathering is the physical breakup of rocks into smaller pieces. Weathering is often confused with erosion. Erosion is the removal of rock by gravity, wind, and water once it has weathered. This confusion is understandable because they are often intertwined.
Plate tectonics is the driving force for faulting, earthquakes, and the melting and pressure that recycles rocks into new igneous and metamorphic rocks. The Earth has several layers: crust, mantle, outer core and inner core. The lithosphere, which is the crust plus the upper part of the mantle, is broken up into different pieces called plates that move around in different directions on the Earth’s surface. Three basic types of boundaries can be found between these plates. Convergent boundaries are where plates crash together. In this case, one plate usually descends beneath the other. Plates made up of oceanic crust are thinner and heavier, so they sink below the lighter, thicker continental plates. Here, friction causes massive pressure, earthquakes, faulting, and mountain building. The descending plate melts, only to rise as a liquid magma and form volcanoes along the edge of the overriding plate. Sometimes, when both lithospheric plates are made of continental crust, neither plate descends, and the earthquakes and faulting create massive mountains such as the Himalayas. Divergent plate boundaries, or rifts are where plates spread apart, usually in the middle of oceans. Basaltic lavas flow from these boundaries, creating new crust. Transform plate boundaries, where plates slide by each other, are illustrated by the San Andreas fault in California. Friction at these boundaries creates earthquakes and faulting.
Between a Rock and an Arch Place
Essential question: How do the characteristics of rocks affect how they interact?
Materials: Google Slides with directions and rock key (send to teacher in advance): 1 of each rock sample for every student (limestone, sandstone, diorite, chert); hand lenses; dixie cups; pipettes; paper towels (1-2 per student); “Rock Mystery” worksheets (1 per student); example of a stone tool made of chert (like an arrowhead); Rock key (1 per student)
Notes on prep: Wash rocks and dry them before pre-trip. Pre-sort chert with good edges that light shines through.
Procedure:
1) Ask students to name any of the arches they remember visiting in the Moab area. Show pictures of Delicate Arch and Crawl Through Arch. Encourage students to recall visiting them and ask if they were formed the same way? Explain that weathering and erosion are part of the story of how arches formed, but weathering and erosion take place all over the earth. Why do we see more in places like Arches than elsewhere? (5 min)
2) Tell students they will be observing rocks and doing investigations to discover characteristics of rocks found in the Moab area. Show students the identification key and demonstrate how it works. Pass out the “Mystery Rock” worksheet and a paper towel to each student (demonstrate how to write numbers 1-4 on the paper towel to label the rocks). Walk students through the rock investigation directions (using the projector) before handing out rocks (tip: start with chert and sandstone). Have students follow the identification key, perform the tests, and answer questions to discover the type of rocks they have and their distinguishing features. Make sure water cups are set around the room so students can fill their pipettes. (25 min)
3) Discuss why investigating rocks is important. Each rock has distinguishing characteristics, which make it unique. These characteristics help people determine how they can be used and provide clues about the ways weathering and erosion shape natural landscapes. Have students hold up a rock that light shines through (chert) and ask what other things make this rock unique. Explain while this rock is good for making arrowheads and stone tools, it doesn’t form arches. Have students hold up the rock with fossils (limestone). Have them hold up the rock with rounded edges like a river rock and has speckles (diorite). Explain how this igneous rock forms and where it is found. Finally, have students hold up the rock sand rubs off (sandstone), and discuss how this rock also absorbed water like a sponge. Explain this rock forms arches. (5 min)
4) Tell students Arches looks the way it does because of its rocks: how they act and how they’re stacked. On the field trip we will be exploring more characteristics of Moab rocks and how they weather and erode. If time, review the difference between weathering and erosion, and ask if they think these rocks will break apart differently. Remind students about what to bring on the field trip. (5 min)
Essential question: How do the characteristics of rocks affect how they interact?
Materials: Google Slides with directions and rock key (send to teacher in advance): 1 of each rock sample for every student (limestone, sandstone, diorite, chert); hand lenses; dixie cups; pipettes; paper towels (1-2 per student); “Rock Mystery” worksheets (1 per student); example of a stone tool made of chert (like an arrowhead); Rock key (1 per student)
Notes on prep: Wash rocks and dry them before pre-trip. Pre-sort chert with good edges that light shines through.
Procedure:
1) Ask students to name any of the arches they remember visiting in the Moab area. Show pictures of Delicate Arch and Crawl Through Arch. Encourage students to recall visiting them and ask if they were formed the same way? Explain that weathering and erosion are part of the story of how arches formed, but weathering and erosion take place all over the earth. Why do we see more in places like Arches than elsewhere? (5 min)
2) Tell students they will be observing rocks and doing investigations to discover characteristics of rocks found in the Moab area. Show students the identification key and demonstrate how it works. Pass out the “Mystery Rock” worksheet and a paper towel to each student (demonstrate how to write numbers 1-4 on the paper towel to label the rocks). Walk students through the rock investigation directions (using the projector) before handing out rocks (tip: start with chert and sandstone). Have students follow the identification key, perform the tests, and answer questions to discover the type of rocks they have and their distinguishing features. Make sure water cups are set around the room so students can fill their pipettes. (25 min)
3) Discuss why investigating rocks is important. Each rock has distinguishing characteristics, which make it unique. These characteristics help people determine how they can be used and provide clues about the ways weathering and erosion shape natural landscapes. Have students hold up a rock that light shines through (chert) and ask what other things make this rock unique. Explain while this rock is good for making arrowheads and stone tools, it doesn’t form arches. Have students hold up the rock with fossils (limestone). Have them hold up the rock with rounded edges like a river rock and has speckles (diorite). Explain how this igneous rock forms and where it is found. Finally, have students hold up the rock sand rubs off (sandstone), and discuss how this rock also absorbed water like a sponge. Explain this rock forms arches. (5 min)
4) Tell students Arches looks the way it does because of its rocks: how they act and how they’re stacked. On the field trip we will be exploring more characteristics of Moab rocks and how they weather and erode. If time, review the difference between weathering and erosion, and ask if they think these rocks will break apart differently. Remind students about what to bring on the field trip. (5 min)
Fossil Frolic
Essential question: What creatures lived here when Arches was under the ocean?
Materials: fossils; fossil ID flip book; CCOE fossil field guides; poster of layers.
Procedure:
1) Show students limestone rocks, and ask what they remember about limestone from the pre-trip. If it is after lunch, ask students what types of rocks they mostly see at Arches and contrast that with limestone. Ask students if either of these rocks could provide evidence that Arches was once under an ocean, as discussed in the movie. Show students the picture of the ancient marine environment and explain what the environment looked like here 300 million years ago. Briefly explain the land where Arches is now was near the equator. It moved because of plate tectonics. It was a tropical environment, with a shallow sea, allowing sunlight to reach the bottom and supporting lots of creatures. Discuss how remains of sea life were turned into fossils. (2-3 min)
2) Briefly pass around and discuss each fossil creature, encouraging students to ask questions. Use the flip book to discuss each fossil creature, disclosing how the creature lived and how to recognize the fossil. For example, crinoids were animals rooted on the ocean bottom and were filter feeders. (Have students suck air in between clenched teeth.) Discuss the difference between fossils and fossil impressions. Use the trilobite to discuss why no one should take things from parks. (5min)
3) Bring students to a piece of green limestone and compare to the red sandstone, letting students determine which will contain fossils. Give boundaries and have students practice calling each other over when they find cool fossils. Give them CCOE field guides to identify the fossils they find. Spend 15 minutes finding fossils and sharing their enthusiasm.
4) When 5-7 minutes remain, gather students. Have students stand in a circle. Place the fossils in the center of the circle. Have everyone face away from the circle, except for one student. Give the student one minute to describe a fossil in the pile using as much detail as possible. Afterwards, the other students will turn around and take turns trying to guess which rock was being described. Students may point to the fossil but not touch it. (5 -7 min)
Extension: Have students sit in a circle for a silly game to reinforce the names of the common fossils in the area by playing the “A What?” game. Show a brachiopod (example). Hand it to student (A) and say, “This is a brachiopod.” Instruct student A to ask, “a what?” Respond, “a brachiopod.” Student A will then pass the fossil to student B, saying, “This is a brachiopod.” That student responds, “a what?” Student A turns to you and says, “a what?" You respond, “a brachiopod.” The “a what?” question must always come back to the person who first passed the fossil, and the answer (“a brachiopod”) must be passed all the way back to the student holding the fossil. Continue until the brachiopod completes the circle, and then start a different fossil. After two or three rounds, start two fossils at the same time, going in opposite directions around the circle.
Who's Fault Is It Anyway?
Essential Question: How does the environment when a rock layer is formed affect its characteristics?
Materials: strata charts; labeled photos of layers in area (1 per student); rocks from each layer; fault strata model; rock layer environment poster; labeled photographs the environments that created each layer; Ancient Landscapes maps; layer model bags for each layer with: clays, styluses, and imprint items; cardboard pieces.
Procedure:
1) Ask students to look around at the rocks and describe similarities and differences. Point out distinct, relatively flat layers. Discuss how each layer began as sediments deposited in different climates. Have students make a human model of rock strata by having them line up oldest to youngest, including yourself and chaperones.Once students are lined up, have everyone sit in a circle while staying in age order. Hand out a labeled photograph of the rock layers to each student. Starting with the oldest, hand out a layer card to each student and point out their assigned layer on the canyon wall. Explain what the environment looked like when each layer was formed, and show students the map from each time period. (3-5 min).
2) Give each student a bag with their clay and modeling items. Tell students they will be creating mini-models of the environments in which their layer was formed. Use your layer as an example. Show students how to flatten the clay, and then use the stylus to shape the clay into different textures and designs based on the environment where the layer was formed. Give students 5 minutes to work on their layers. (5-7 min)
3) Have students present their layers, and then stack the clay layers in order. Review how differing environments affect each layer's characteristics.(5 min)
4) Ask students to compare how this model is similar and different from the layers in the real world. Peel off the top 3 layers of the model and put them next to the model. Share that you notice the younger layers (Navajo, Carmel, and Entrada) are lower in elevation than the Kayenta. Have students speculate about what might cause this phenomenon. Tell students you have another clue. But first, students should smash their clay layer back into a ball and put it back into the bag with the stylus and sculpting materials. (2-3 min)
5) Walk students over to the fault area. Encourage them to describe rocks on both sides of the fault. Point out the slickenside scratches on the rock, and explain these resulted from rocks moving past each other along the fault. Ask students what we call it when rocks move. Ask if anyone has ever experienced an earthquake? Allow students to share their earthquake stories. Refer to the movie and the movement of salt underneath Arches which caused the movement of rocks. Stress that earthquakes in Moab are not caused by movements along the tectonic plates. They are caused by salt moving beneath the earth. Explain how we measure earthquakes using the Richter scale. The more pressure builds up, the more the rocks move, and the bigger the earthquake. Moab has small earthquakes. Remind students that an earthquake is an event, and a fault is a place. (3-5 min)
6) Hold up the rock strata model. Have students hold up their hands, palms facing you. As you move the east side layers down until the Carmel layer reaches the Hermosa layer, have students enact the movement with their hands. Be sure to make appropriate rock crushing noises! Ask students what happened to the Navajo, Carmel, and Entrada layers on the western side of the fault. Remove these layers from the model to simulate how the upper layers eroded away. Discuss how this model is similar to the history of the Moab Fault but on a much faster time scale. Allow students to touch both layers at the fault. (3-5 min)
Extension: Give each student a rock from their layer. Reinforce the understanding of superposition by having students attempt to stack their rocks, the oldest formation on the bottom and the youngest on the top. Have students see how high they can stack their rocks, without touching any of the rocks underneath, before they fall. (5-7 minutes)
Clay sculpturing ideas:
Hermosa (sea): green clay, small sea shell imprints, waves
Cutler (fluvial deposits): red clay, river squiggles, eroding mountains, gloopy mud
Moenkopi (tidal flat): dark brown/red, ocean waves and beach, squiggly rivers
Chinle (swamp): gray/purple/green, piece of moss/leaf imprint, gloopy mud, stick imprints/wood
Wingate (sand dunes): red clay, sand dunes/crossbedding, imprint with sandstone, dino tracks
Kayenta (braided streams): light brown clay, dino tracks, braided squiggles
Navajo (sand dunes): white/yellow clay, sand dune/crossbedding, sandstone imprint, dino tracks
Carmel (tidal mud flat): dark red/brown, dino tracks, ocean waves, gloopy mud
Entrada (sand dunes): red, dino tracks, sand dunes/crossbedding, sandstone imprint
Essential Question: How does the environment when a rock layer is formed affect its characteristics?
Materials: strata charts; labeled photos of layers in area (1 per student); rocks from each layer; fault strata model; rock layer environment poster; labeled photographs the environments that created each layer; Ancient Landscapes maps; layer model bags for each layer with: clays, styluses, and imprint items; cardboard pieces.
Procedure:
1) Ask students to look around at the rocks and describe similarities and differences. Point out distinct, relatively flat layers. Discuss how each layer began as sediments deposited in different climates. Have students make a human model of rock strata by having them line up oldest to youngest, including yourself and chaperones.Once students are lined up, have everyone sit in a circle while staying in age order. Hand out a labeled photograph of the rock layers to each student. Starting with the oldest, hand out a layer card to each student and point out their assigned layer on the canyon wall. Explain what the environment looked like when each layer was formed, and show students the map from each time period. (3-5 min).
2) Give each student a bag with their clay and modeling items. Tell students they will be creating mini-models of the environments in which their layer was formed. Use your layer as an example. Show students how to flatten the clay, and then use the stylus to shape the clay into different textures and designs based on the environment where the layer was formed. Give students 5 minutes to work on their layers. (5-7 min)
3) Have students present their layers, and then stack the clay layers in order. Review how differing environments affect each layer's characteristics.(5 min)
4) Ask students to compare how this model is similar and different from the layers in the real world. Peel off the top 3 layers of the model and put them next to the model. Share that you notice the younger layers (Navajo, Carmel, and Entrada) are lower in elevation than the Kayenta. Have students speculate about what might cause this phenomenon. Tell students you have another clue. But first, students should smash their clay layer back into a ball and put it back into the bag with the stylus and sculpting materials. (2-3 min)
5) Walk students over to the fault area. Encourage them to describe rocks on both sides of the fault. Point out the slickenside scratches on the rock, and explain these resulted from rocks moving past each other along the fault. Ask students what we call it when rocks move. Ask if anyone has ever experienced an earthquake? Allow students to share their earthquake stories. Refer to the movie and the movement of salt underneath Arches which caused the movement of rocks. Stress that earthquakes in Moab are not caused by movements along the tectonic plates. They are caused by salt moving beneath the earth. Explain how we measure earthquakes using the Richter scale. The more pressure builds up, the more the rocks move, and the bigger the earthquake. Moab has small earthquakes. Remind students that an earthquake is an event, and a fault is a place. (3-5 min)
6) Hold up the rock strata model. Have students hold up their hands, palms facing you. As you move the east side layers down until the Carmel layer reaches the Hermosa layer, have students enact the movement with their hands. Be sure to make appropriate rock crushing noises! Ask students what happened to the Navajo, Carmel, and Entrada layers on the western side of the fault. Remove these layers from the model to simulate how the upper layers eroded away. Discuss how this model is similar to the history of the Moab Fault but on a much faster time scale. Allow students to touch both layers at the fault. (3-5 min)
Extension: Give each student a rock from their layer. Reinforce the understanding of superposition by having students attempt to stack their rocks, the oldest formation on the bottom and the youngest on the top. Have students see how high they can stack their rocks, without touching any of the rocks underneath, before they fall. (5-7 minutes)
Clay sculpturing ideas:
Hermosa (sea): green clay, small sea shell imprints, waves
Cutler (fluvial deposits): red clay, river squiggles, eroding mountains, gloopy mud
Moenkopi (tidal flat): dark brown/red, ocean waves and beach, squiggly rivers
Chinle (swamp): gray/purple/green, piece of moss/leaf imprint, gloopy mud, stick imprints/wood
Wingate (sand dunes): red clay, sand dunes/crossbedding, imprint with sandstone, dino tracks
Kayenta (braided streams): light brown clay, dino tracks, braided squiggles
Navajo (sand dunes): white/yellow clay, sand dune/crossbedding, sandstone imprint, dino tracks
Carmel (tidal mud flat): dark red/brown, dino tracks, ocean waves, gloopy mud
Entrada (sand dunes): red, dino tracks, sand dunes/crossbedding, sandstone imprint
Why so many Arches?
Essential Question: How do the characteristics and order of rock layers cause arches to form?
Materials for each group: sand dune and tidal flat photo books; squeeze bottle; wood styluses.
Procedure:
1) Discuss what types of rock make up the La Sal Mountains and Park Avenue. Ask students to share what they notice about the rock layers. Tell them more arches can be found in Arches National Park than anywhere else in the world, and we will be discovering why. (3-5 min)
2) Tell students they are going to develop a model of how this area formed, which will also illustrate the definitions of weathering and erosion. Have two students create the Uncompahgre Mountains by building a mountain of sand. Choose two other students to dig out a shallow ocean basin below using flat rocks. As they build, discuss the type of rock that makes up the mountains. Explain how the mountains break down, and discuss the different types of weathering they learned about on their fall field trip to ISKY. Have each student weather the mountain with their fingers for the count of three, and then erode the sand into the basin. Name each layer after them and discuss how the layers formed first are the oldest layers. (3-5 min)
3) Explain that Park Ave was once one continuous block of rock, like the now filled basin in the model. Show the Strata of Arches chart and explain each layer’s position. Ask students to describe what happened to the layers above where they are standing and the locations of the layers below. Invite students to explain how the canyon formed. To illustrate, drag a rock through the center of the layers in the model. Discuss the group’s current location in the model. Show the Park Avenue strata chart and discuss which layer is the oldest. (3-5 min)
4) Stop at a noticeably cross-bedded section of Navajo Sandstone. Have students closely observe and touch the rock and share their observations. Do they observe a pattern? Show the crossbedding photo, and explain we still see this pattern in Navajo Sandstone. Using the photos, explain crossbedding. The crossbedding pattern is a clue that Navajo was once a windblown sand dune. Encourage students to search for a similar pattern on the rocks below our feet as we continue hiking. (2-3 min)
5) Show the Park Ave strata. Ask students to identify which layer is on top of Navajo Sandstone. Point out the Carmel Formation rocks. As the group continues walking, encourage students to look for rocks on the trail that eroded from above. Approach a large boulder from the Carmel Formation and ask students where it came from? If they do not guess, point to the Carmel layer up above, comparing the large-scale pattern to wavy lasagna. Have students closely observe the boulder and layer and share their observations. Compare and contrast this rock with the Navajo rock they observed. Recall characteristics of the rocks observed in the pre-trip as well. If students have not already, explain there is no crossbedding. Using the mud photo, explain the wavy lumpy pattern and lack of crossbedding are clues Carmel was once a wet muddy tidal flat. Ask students to share where they have experienced similar mud flats and describe their feel. Show the Park Ave layers image and ask students to name the next layer younger than Carmel. Explain this layer is where most arches form. Tell students to look out for an arch up ahead. (5 min)
6) Once students see Baby Arch, tell students arches are often named for something they look like. Have students suggest their names for the arch. Ask students to theorize how it formed. Use the Park Avenue strata to encourage students to name which layer the arch is in. Tell students Entrada means entrance in Spanish, which is perfect since most arches in the park can be found in this layer. Point out the crossbedding under the Three Gossips, and ask students what this clue tells us about the environment when the rock was formed? (3-5 min)
7) Show students the Carmel and Entrada model. Discuss how the marbles represent the larger sand grains in Entrada, and the sand represents the smaller sand grains in Carmel. Ask students to predict what might happen if we pour water on each? Have a student pour several drops of water on the models and observe the results. Stack the Entrada rock sample on top of the Carmel sample and ask students where they think the most weathering and erosion takes place? Where will the water collect and weaken the rock? Next, stack the Entrada model on the Carmel model, and again ask students where water will collect and weather the rock? Again, pour water on the model and discuss the results. Explain how water seeps through Entrada like a sponge. When the water reaches a less porous layer such as Carmel, it stops, collects, and seeps out. As the water sits, it dissolves the glue holding the sand grains together, creating a prime area for weathering and erosion. Point out this boundary on the surrounding walls. Have students draw lines between the layers on the Cove of Caves and Double Arch photos. Using the photo of Delicate Arch, explain how weathering can also happen inside of an Entrada rock along the boundary of a well-cemented bedding plane of Entrada. Ask students if they think Baby Arch might look like Delicate Arch in the future. (3-5 min)
8) Take students to a sandy area to build an arch. Show them how to create a small wall of sand. Hand each student a stylus to pick away at the wall, making the wall thinner and thinner, until an arch forms. Ask students if they think so many arches are here because we have more weathering and erosion or because of the order of the rock layers. Remind students over 2,000 named arches are in the park and most of them are found within the Slick Rock member of Entrada Sandstone.
9) Ask students to look back up the canyon and observe the rock layers are similar on both sides of the wash. Using the canyon model, discuss what happened to the missing rock. (5-10 min)
Cool facts about the layers we see:
Navajo Sandstone:
- Light brown/grey- High-angle crossbedding
- Aeolian deposit
- Fine-grained
- Well-sorted
- Cemented with calcite and quartz
- The “Petrified Sand Dunes” & bottom of Park Ave (look for cross bedding/swirls)
Dewey Bridge Member of the Carmel Formation:
- Red-brown/chocolate brown
- Alluvial deposits
- “Lumpy” bedding
- Muddy/silty
- Fine-grained
- Deposited on broad tidal flats marginal to a shallow sea (Carmel Sea) to the west
- The bottom of Balanced Rock & the Windows
Slick Rock Member of Entrada Sandstone:
- The most important geologic unit at Arches!
- Red-orange/brown
- Striped or banded in color
- Well-indurated (hardened)
- Very fine-grained, contains sparse & scattered medium to coarse grains
- Cemented with calcite and iron-oxide
- Commonly weathers to form smooth cliffs and bare-rock slopes
- Parts are cross-stratified (Aeolian deposition), others parts are planar bedding
- Small holes (tafoni) are commonly aligned along fine cross bedded layers
- Arches occur:
- Along lower contact (Dewey Bridge)
- Along upper contact (Moab Member)
- Along “partings”/unconformities in the middle of the unit
Essential Question: How do the characteristics and order of rock layers cause arches to form?
Materials for each group: sand dune and tidal flat photo books; squeeze bottle; wood styluses.
Procedure:
1) Discuss what types of rock make up the La Sal Mountains and Park Avenue. Ask students to share what they notice about the rock layers. Tell them more arches can be found in Arches National Park than anywhere else in the world, and we will be discovering why. (3-5 min)
2) Tell students they are going to develop a model of how this area formed, which will also illustrate the definitions of weathering and erosion. Have two students create the Uncompahgre Mountains by building a mountain of sand. Choose two other students to dig out a shallow ocean basin below using flat rocks. As they build, discuss the type of rock that makes up the mountains. Explain how the mountains break down, and discuss the different types of weathering they learned about on their fall field trip to ISKY. Have each student weather the mountain with their fingers for the count of three, and then erode the sand into the basin. Name each layer after them and discuss how the layers formed first are the oldest layers. (3-5 min)
3) Explain that Park Ave was once one continuous block of rock, like the now filled basin in the model. Show the Strata of Arches chart and explain each layer’s position. Ask students to describe what happened to the layers above where they are standing and the locations of the layers below. Invite students to explain how the canyon formed. To illustrate, drag a rock through the center of the layers in the model. Discuss the group’s current location in the model. Show the Park Avenue strata chart and discuss which layer is the oldest. (3-5 min)
4) Stop at a noticeably cross-bedded section of Navajo Sandstone. Have students closely observe and touch the rock and share their observations. Do they observe a pattern? Show the crossbedding photo, and explain we still see this pattern in Navajo Sandstone. Using the photos, explain crossbedding. The crossbedding pattern is a clue that Navajo was once a windblown sand dune. Encourage students to search for a similar pattern on the rocks below our feet as we continue hiking. (2-3 min)
5) Show the Park Ave strata. Ask students to identify which layer is on top of Navajo Sandstone. Point out the Carmel Formation rocks. As the group continues walking, encourage students to look for rocks on the trail that eroded from above. Approach a large boulder from the Carmel Formation and ask students where it came from? If they do not guess, point to the Carmel layer up above, comparing the large-scale pattern to wavy lasagna. Have students closely observe the boulder and layer and share their observations. Compare and contrast this rock with the Navajo rock they observed. Recall characteristics of the rocks observed in the pre-trip as well. If students have not already, explain there is no crossbedding. Using the mud photo, explain the wavy lumpy pattern and lack of crossbedding are clues Carmel was once a wet muddy tidal flat. Ask students to share where they have experienced similar mud flats and describe their feel. Show the Park Ave layers image and ask students to name the next layer younger than Carmel. Explain this layer is where most arches form. Tell students to look out for an arch up ahead. (5 min)
6) Once students see Baby Arch, tell students arches are often named for something they look like. Have students suggest their names for the arch. Ask students to theorize how it formed. Use the Park Avenue strata to encourage students to name which layer the arch is in. Tell students Entrada means entrance in Spanish, which is perfect since most arches in the park can be found in this layer. Point out the crossbedding under the Three Gossips, and ask students what this clue tells us about the environment when the rock was formed? (3-5 min)
7) Show students the Carmel and Entrada model. Discuss how the marbles represent the larger sand grains in Entrada, and the sand represents the smaller sand grains in Carmel. Ask students to predict what might happen if we pour water on each? Have a student pour several drops of water on the models and observe the results. Stack the Entrada rock sample on top of the Carmel sample and ask students where they think the most weathering and erosion takes place? Where will the water collect and weaken the rock? Next, stack the Entrada model on the Carmel model, and again ask students where water will collect and weather the rock? Again, pour water on the model and discuss the results. Explain how water seeps through Entrada like a sponge. When the water reaches a less porous layer such as Carmel, it stops, collects, and seeps out. As the water sits, it dissolves the glue holding the sand grains together, creating a prime area for weathering and erosion. Point out this boundary on the surrounding walls. Have students draw lines between the layers on the Cove of Caves and Double Arch photos. Using the photo of Delicate Arch, explain how weathering can also happen inside of an Entrada rock along the boundary of a well-cemented bedding plane of Entrada. Ask students if they think Baby Arch might look like Delicate Arch in the future. (3-5 min)
8) Take students to a sandy area to build an arch. Show them how to create a small wall of sand. Hand each student a stylus to pick away at the wall, making the wall thinner and thinner, until an arch forms. Ask students if they think so many arches are here because we have more weathering and erosion or because of the order of the rock layers. Remind students over 2,000 named arches are in the park and most of them are found within the Slick Rock member of Entrada Sandstone.
9) Ask students to look back up the canyon and observe the rock layers are similar on both sides of the wash. Using the canyon model, discuss what happened to the missing rock. (5-10 min)
Cool facts about the layers we see:
Navajo Sandstone:
- Light brown/grey- High-angle crossbedding
- Aeolian deposit
- Fine-grained
- Well-sorted
- Cemented with calcite and quartz
- The “Petrified Sand Dunes” & bottom of Park Ave (look for cross bedding/swirls)
Dewey Bridge Member of the Carmel Formation:
- Red-brown/chocolate brown
- Alluvial deposits
- “Lumpy” bedding
- Muddy/silty
- Fine-grained
- Deposited on broad tidal flats marginal to a shallow sea (Carmel Sea) to the west
- The bottom of Balanced Rock & the Windows
Slick Rock Member of Entrada Sandstone:
- The most important geologic unit at Arches!
- Red-orange/brown
- Striped or banded in color
- Well-indurated (hardened)
- Very fine-grained, contains sparse & scattered medium to coarse grains
- Cemented with calcite and iron-oxide
- Commonly weathers to form smooth cliffs and bare-rock slopes
- Parts are cross-stratified (Aeolian deposition), others parts are planar bedding
- Small holes (tafoni) are commonly aligned along fine cross bedded layers
- Arches occur:
- Along lower contact (Dewey Bridge)
- Along upper contact (Moab Member)
- Along “partings”/unconformities in the middle of the unit
Plates on the Go
Objectives: Students will be able to:a. Explain why earthquakes are most common along plate boundaries.b. Explain how plate tectonics creates new igneous and metamorphic rocks.
Question: Where do large earthquakes often occur on Earth?
Materials: Analyzing and Interpreting data graphic organizer worksheets (one per student); computers for each student; presentation showing photographs of places with recent earthquakes; presentation showing how to use USGS website (earthquake.usgs.gov)
Procedure:
1) Review concepts and experiences from the field trip. Remind them of the fault they examined on their field trip. Discuss earthquakes, incorporating what an earthquake is, how long earthquakes normally last, earthquake magnitude, and how scientists measure an earthquake’s magnitude. Invite students to share their earthquake stories. Show students pictures of a richtor scale recording earthquake data. Explain how a 5.5 quake is ten times more intense than a 4.5 quake. Remind students earthquakes are caused by rocks moving along fractures, or faults, in the earth. Earthquakes are events, and a fault is a place.
2) Show students images of a few recent locations of large and small earthquakes and their magnitude. Ask students to describe patterns they observe and what they notice about the locations of big earthquakes on earth. Tell students you notice that “only small earthquakes happen near Moab,” and ask students to share their ideas about why that is. (5 minutes).
3) Tell students they will analyze data to discover why only small earthquakes happen near Moab. Pass out the Analyzing and Interpreting Data graphic organizer and have students record this guiding question. (3-5 minutes)
4) Show students how to gather information by collecting data and mapping locations of large and small earthquake data from the USGS website. Demonstrate how to use the website. Split students into teams (2-3 students) to plot earthquakes. Assign each team to an earthquake magnitude, either small (7 days, Magnitude 2.5+) or large (30 Days, Significant Worldwide). Have groups record earthquake locations and magnitudes. (15 minutes)
5) Pair up groups (low magnitude with high magnitude) to compare the locations and find similarities and differences. Each pair of groups will evaluate their data by identifying relationships between earthquake magnitude and locations. (5-7 minutes)
6) Come back together as a class and invite students to share their findings. (5 minutes)
7) Pull up the USGS website in front of the class, and show the “US fault lines” and “plate boundaries” so students can compare them to their maps. Students will (hopefully) make the conclusions about low magnitudes along fault lines and higher magnitudes on plate boundaries. Then, show images of plate boundaries and fault lines to reinforce what those look like in real life. Discuss why large earthquakes are near plate boundaries and small earthquakes occur near fault lines. Have students compare their conclusions from the data to the phenomenon. For an additional 3D view of the plate boundaries, have teacher log into earthquake video and show the rotation of the earth with earthquakes. http://sos.noaa.gov/Datasets/dataset.php?id=643 (10 minutes)
Extension: Earthquake Trivia: Point out the three major earthquakes that show up as big splashes of color/ large dots
Objectives: Students will be able to:a. Explain why earthquakes are most common along plate boundaries.b. Explain how plate tectonics creates new igneous and metamorphic rocks.
Question: Where do large earthquakes often occur on Earth?
Materials: Analyzing and Interpreting data graphic organizer worksheets (one per student); computers for each student; presentation showing photographs of places with recent earthquakes; presentation showing how to use USGS website (earthquake.usgs.gov)
Procedure:
1) Review concepts and experiences from the field trip. Remind them of the fault they examined on their field trip. Discuss earthquakes, incorporating what an earthquake is, how long earthquakes normally last, earthquake magnitude, and how scientists measure an earthquake’s magnitude. Invite students to share their earthquake stories. Show students pictures of a richtor scale recording earthquake data. Explain how a 5.5 quake is ten times more intense than a 4.5 quake. Remind students earthquakes are caused by rocks moving along fractures, or faults, in the earth. Earthquakes are events, and a fault is a place.
2) Show students images of a few recent locations of large and small earthquakes and their magnitude. Ask students to describe patterns they observe and what they notice about the locations of big earthquakes on earth. Tell students you notice that “only small earthquakes happen near Moab,” and ask students to share their ideas about why that is. (5 minutes).
3) Tell students they will analyze data to discover why only small earthquakes happen near Moab. Pass out the Analyzing and Interpreting Data graphic organizer and have students record this guiding question. (3-5 minutes)
4) Show students how to gather information by collecting data and mapping locations of large and small earthquake data from the USGS website. Demonstrate how to use the website. Split students into teams (2-3 students) to plot earthquakes. Assign each team to an earthquake magnitude, either small (7 days, Magnitude 2.5+) or large (30 Days, Significant Worldwide). Have groups record earthquake locations and magnitudes. (15 minutes)
5) Pair up groups (low magnitude with high magnitude) to compare the locations and find similarities and differences. Each pair of groups will evaluate their data by identifying relationships between earthquake magnitude and locations. (5-7 minutes)
6) Come back together as a class and invite students to share their findings. (5 minutes)
7) Pull up the USGS website in front of the class, and show the “US fault lines” and “plate boundaries” so students can compare them to their maps. Students will (hopefully) make the conclusions about low magnitudes along fault lines and higher magnitudes on plate boundaries. Then, show images of plate boundaries and fault lines to reinforce what those look like in real life. Discuss why large earthquakes are near plate boundaries and small earthquakes occur near fault lines. Have students compare their conclusions from the data to the phenomenon. For an additional 3D view of the plate boundaries, have teacher log into earthquake video and show the rotation of the earth with earthquakes. http://sos.noaa.gov/Datasets/dataset.php?id=643 (10 minutes)
Extension: Earthquake Trivia: Point out the three major earthquakes that show up as big splashes of color/ large dots
- Dec 26, 2004 - 9.1 Boxing Day earthquake in Sumatra produced a 100 foot tall tsunami (as high as two HMK schools stacked on top of each other)
- Feb 27, 2010 - 8.8 off the shore of Chile
- March 11, 2011 - 9.1 Japan 4th most powerful earthquake in the world since 1900; 133 foot high tsunami that traveled 6 miles inland
- Also- talk about how the ring of fire has 90% of the world’s earthquakes and 452 volcanoes (75% of the world’s volcanoes)
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Last updated: July 26, 2022