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Home , Checkerboard Mesa, Erosion, Geological survey, Lithification, Mesa, Rock (geology)

National Park Service U.S. Department of the Interior

Zion

Weathering, , and Change Geologic Events in Zion

PHOTO CREDIT Contents

Introduction 2

Core Connections 2

Background 2

Activities ’s Power Punches 4 On, Zion 5 It Happened Here! 6

Glossary 8

References 9 Introduction

This guide contains background information about how , erosion, and other geologic processes such as volcanoes continually shape the , and directions for three activities that will help students better understand how these processes are at work in . This guide is specifically designed for fifth grade classrooms, but the activities can be

NPS modified for students at other levels.

Theme of (), , The Earth’s surface is a dynamic system that is uplift, weathering, erosion, tectonics, and constantly changing due to weathering, volcanic activity make the park a showcase for erosion, , , volcanoes, and changing . other geologic events. Deposition (Sedimentation) Focus was a relatively flat basin The activities focus on relationship between near level 275 million years ago, near the NPS/MARC NEIDIG geologic processes such as weathering and of Pangaea, the land area believed to erosion and changes on the Earth’s surface. have once connected nearly all of the earth’s landmasses together. As , , and Activities muds eroded from surrounding , Earth’s Power Punches carried these materials into the Students view a presentation of digital im- basin and deposited them in layers. The sheer ages showing the forces that shape the Earth’s weight of these accumulated layers caused surface. Then students view images from Zion the basin to sink, so that the top surface and determine which geologic forces have always remained near . As the land contributed to the landscapes shown. rose and fell and as the changed, the NPS/CAITLIN CECI depositional environment fluctuated from Weathering and erosion are shallow to coastal to a massive some of the Earth processes that Rock On, Zion shape the and scenery of windblown . This process of Students will learn how Zion was formed and in Zion National Park. sedimentation continued until over 10,000 evaluate how weathering and erosion contrib- feet of material accumulated. uted to the formation of the rock layers and subsequent carving of the . Core Connections Lithification -laden slowly filtered Utah Core Curriculum It Happened Here! through the compacted . Fifth Grade Science Students draw on the knowledge they have oxide, calcium , and silica Standard 2: Students will gained about geologic events to invent a spe- acted as cementing agents, and with pressure understand that volcanoes, cific event and imagine themselves in it. from overlying layers over long periods of earthquakes, uplift, time, transformed the deposits into stone. weathering, and erosion reshape Earth’s surface. Ancient became ; mud and Background became mudstones and ; and sand and sand became . Each Objective 1: Describe how Zion National Park is located along the edge weathering and erosion layer originated from a distinct source and so of a region called the . Uplift, change Earth’s surface. differs in thickness, mineral content, color, tilting, and the erosion of rock layers formed and eroded appearance. Objective 2: Explain how a feature called the , a series volcanoes, earthquakes, and of colorful cliffs stretching between Bryce uplift affect Earth’s surface. Tectonics and Uplift Canyon, Zion, and the . In an area from Zion to the , Objective 3: Relate the building tectonic forces deep within the Earth up and breaking down of Zion has spectacular geology. The arid climate pushed the surface up creating the Colorado Earth’s surface over time to the and sparse expose bare rock and various physical land features. Plateau. This was not chaotic uplift, but reveal the park’s geologic history. Evidence

Zion National Park, 2015 Erosion, Weathering, and Change 2 slow vertical hoisting of huge blocks of the The is still excavating. Upstream . Zion’s elevation rose from near sea level from the Temple of Sinawava, in The Narrows, to as high as 10,000 feet above sea level. the river cuts through , Uplift is still occurring. creating a . At the Temple of Sinawava, the river has reached the softer For many millions of years, portions of the below. erodes the Pacific Plate () subducted shale, undermining the overlaying sandstone beneath the thicker, more buoyant North and causing it to collapse, widening the American Plate (). This canyon. As the continue to rise, the subduction formed mountains and volcanoes basins drop, and the river cuts, along the west coast, and led to the formation is expanding upstream at a rate of about 10 of the Rocky Mountains. Later, changes in miles of lateral movement every million years. plate geometry led to the end of subduction along much of the West Coast (although Volcanic Activity subduction continues today in the Pacific Volcanic vents, created as a result of the Northwest). Instead of being pushed together, weakening of the Earth’s crust during tectonic the plates began to slide sideways (lateral events, allowed flows and cinder cones to motion), as is seen today in ’s form. Cinder was piled several hundred feet San Andreas . This lateral motion high in classic cone shapes and lava flowed stretched portions of western ; into valleys. Cinder cones and black creating a region called the Basin and Range. flows are visible west of Rockville and on the Westernmost Utah is part of the eastern Kolob . edge of the Basin and Range province, where stretching continues today along active and Faults faults like the Hurricane and Wasatch Faults. Fractures and their control of canyon erosion Despite the building and stretching are one of the most striking features of the that of the Virgin River. The fractures (not occurred in the surrounding areas, the faults because there is no displacement) exert rose to its high elevation a strong influence on the erosion of smaller with little deformation. canyons in the Navajo Sandstone.

Erosion These fractures are believed to have formed The uplift of the Colorado Plateau gave the due to tectonic compression and extension streams greater cutting force in their descent forces. The fractures form perpendicular to to the sea. The park’s location on the the direction of the compression and western edge of this uplift caused the streams extension. The dominant direction to tumble off the plateau, flowing rapidly in Zion is roughly north-south. There are also down a steep gradient. These streams began fracture sets that are east-west (Kolob eroding and cutting into the rock layers, Canyons) and northeast–southwest (Kolob forming deep and narrow canyons. Terrace and Hop ).

Grain by grain, the Virgin River has carried While the straight north-south canyons away several thousand feet of rock that once on either side of Checkerboard are lay above the highest layers visible today. On controlled by large fractures, the criss-cross average, the Virgin River transports one fractures on its surface are of a more million tons of per year. The rate recent origin. The horizontal banding is the varies dramatically with the flow of the river, result of differential weathering of the with the vast majority of crossbedded sandstone, while the vertical occurring during floods. When the river is low cracks are thought to be the result of freeze/ and clear, very little sediment is moving, and thaw cycles at the surface of the rock. much of the transport involves dissolved in the water.

Zion National Park, 2015 Erosion, Weathering, and Change 3 Earth’s Power Punches Suggested Procedures 1. Show the Utah State Duration Landscapes presentation and use 1 hour accompanying notes for each slide to introduce students to the variety of Location geologic processes that occur to shape the Indoors Earth. 2. Show each of the Zion landscape images Key Vocabulary and ask the students to name which Earth blind arch, , cinder cone, erosion, process they think was at work to create the , geologic processes, mesa, rock landscape in each image. Have the students layers, uplift, volcanoes, weathering write down a list of Earth changing processes for two or three of the images. Objectives By the end of the activity, students will be able 3. Ask the students to determine which to a) name three Earth processes that shape processes can occur quickly (minutes/ the landscape, b) name two Earth processes hours) and which occur over a long that have helped to change the landscape at period of time (years to millions of years). Zion, c) name which Earth processes have Have students discuss their results with occurred quickly and which have occurred the class and describe the processes they slowly. investigated. Ask the students to describe how they came up with their determination Method of the time it took for each process to Students view a presentation showing occur. geologic processes that contribute to changing landscapes. Applying their knowledge to Zion, students view images and identify evidence of geologic forces such as weathering, erosion, earthquakes, volcanoes, and uplift.

Background The Earth’s surface constantly changes due to weathering, erosion, earthquakes, volcanoes, and uplift. At Zion National Park evidence of these processes is observed in the water and carved rocks, uplifted geologic layers, volcanic flows, cinder cones, , blind arches, and other .

Materials • Utah State Geological Survey presentation of Landscapes located at http://geology. utah.gov/teacher/ppt/utah_landforms.ppt • Earth’s Power Punches images

Zion National Park, 2015 Erosion, Weathering, and Change 4 Rock On, Zion Materials • Rock On, Zion images Duration 1 hour Suggested Procedures 1. Write the word “weathering” on the board, Location then write the word “erosion” on the Indoors board. Ask the students to think of some of the things that might make weathering Key Vocabulary happen such as water and , wind, and chemicals. Then ask the students NPS/ADRIENNE FITZGERALD chemical weathering, deposition, erosion, lithification, , mechanical to think of some things such as water, weathering, plateau, , uplift wind, and that erode (move) the weathered materials. Ask the students to Objectives think about which of these processes might By the end of the activity, students will be able have carved Zion. to a) explain the difference between erosion and weathering, b) explain how weathering 2. Show the rock cycle image and have the and erosion has contributed to the formation students explain how they think the cycle of the rock layers and c) describe how the works. Ask them if the park was always a Virgin River carved Zion Canyon. canyon or if it has changed over time. How NPS/MARC NEIDIG have the processes shown in the rock cycle Method impacted Zion? After viewing images of landforms in Zion National Park and discussing the rock cycle 3. Go through the images of four steps of the images, students will evaluate how weathering rock cycle that have helped to shape Zion. and erosion have contributed to the formation Explain that over several million years, the of the rock layers and subsequent carving of Virgin River weathered and eroded the the canyon. rock layers and made it possible for us to see them. The river once flowed at the top Background of a flat plateau but has carved through the rock layers to its level. NPS/RENDALL SEELY Evidence of weathering and erosion can be Weathering and erosion have observed at the park. Weathering and created much of the dramatic 4. Break the class into five groups, and scenery in Zion National Park. erosion are often confused. assign each group one of the steps in Weathering involves two processes that Zion’s geologic process (sedimentation/ often work together to decompose or deposition, lithification, uplift, weathering, break down rocks. Chemical weathering and erosion). Print out a set of the involves a chemical change in at least some numbered photos in the Rock On, Zion of the minerals within a rock. Mechanical images or display on board. Have each weathering involves physically breaking rocks group determine which images show their into fragments without changing the chemical step in the geologic process. Finally, have make-up of the minerals within it. Weathering students draw one or more new images is a surface or near-surface process. No showing their step. Have each group share movement is involved in weathering. their findings.

Erosion occurs as soon as a rock particle 5. Ask the students how the canyon is likely (loosened by one of the two weathering to change as the Virgin River continues to processes) moves. Mass wasting is simply and erode the movement down slope due to . Rock layers. falls, slumps, and flows are all examples of mass wasting.

Zion National Park, 2015 Erosion, Weathering, and Change 5 It Happened Here!

Duration Materials 1 to 2 hours • It Happened Here! images • writing paper and pens Location • student copies of writing guide (three Indoors types) • classroom computers Key Vocabulary erosion, eyewitness, Hurricane Fault, Suggested Procedure , scientist 1. Show the images to review the kind of landscape changes that can be caused by Objectives weathering and erosion, , rock After this activity, students will be able falls, floods, and earthquakes. to: a) describe a single event from three perspectives, b) name two geological features, 2. Tell students that they are going to draw on and c) describe map features that were created the knowledge they already have about the through landscape changes. geologic events to invent a specific event and imagine themselves in it. Distribute Method copies of the writing guides and ask each Students draw on the knowledge they have student to note the date and time of their gained about geologic events to invent a changing landscape event, the location, specific event and explore the event from how much damage it caused, and other different the different perspectives of a news basic information at the top of the writing reporter, scientist, and eyewitness. guide.

Over millions of years, erosion, weathering, rockfalls, floods, earthquakes, volcanoes, and other geologic events have shaped the landscape that is today Zion National Park. NPS

Zion National Park, 2015 Erosion, Weathering, and Change 6 3. Now tell students that each will write about Evaluation his or her hypothetical geologic event from Ask students to talk about the experience of three different points of view: that of a writing the accounts. news reporter, a scientist, and an individual directly affected by the event. Each of the • Did you feel you had enough information three accounts will describe the same to do the job in each case? landscape-changing event, but the styles of • Did some of you wish you knew more? Is the three will vary: there anything specific you’d like to find out? • News Reporter—a short, concise article • Was one point of view more comfortable NPS describing the who, what, where, and when than the others? Were some accounts easier of the landscape-changing event and to write? providing information the public needs. • Discuss the validity of the different points of view. Emphasize that each kind of • Scientist—a scientific account stating what account is valuable in its own right. is objectively known about the landscape- • Ask students to share how landscape- changing event: its causes, its effects, its changing events might impact Zion magnitude and/or intensity, and the National Park in the future. likelihood of its recurrence, if known. • Ask students to explain how some landscape-changing events might occur NPS/BARB GRAVES • Eyewitness—a personal letter to a friend quickly like an earthquake but that other telling about being in a landscape-changing events like the creation of new rock layers event. This will describe what happened to from deposition of sediments (rock pieces) the student, to the area in which the might take millions of years. student was, to others that might have been with the student at the time of the event. Have students describe what they had done before the event to be prepared, how effective their preparations were, what was like in the two weeks following the NPS event, and what they would do differently Earthquakes, rockfalls, and in preparation for the next event. floods are dramatic examples of geologic events that happen in Zion National Park 4. Tell students to feel free to make up information, quotations, etc., but to keep the basic facts consistent from one essay to another. However, since in real life compositions of the second and third type are likely to be written later than news accounts, some discrepancies in details are to be expected.

Zion National Park, 2015 Erosion, Weathering, and Change 7 Glossary

fault: the boundary between two rock Basin and Range: type of topography that is sections that have been displaced relative to characterized by a series of tilted fault blocks each other. forming or mountains and broad, intervening basins or valleys. : a bend in a layer of rock. blind arch: a curved structure created by : the mineralized or otherwise preserved natural geological forces causing rock to fall remains or traces (such as footprints) of away, with a rock face behind so there is no animals, , and other organisms. window through the arch.

geology: the science and study of the butte: a steep-sided with a flat top, often earth and the processes by which it is shaped standing alone in an otherwise flat area. A and changed. butte is smaller than a mesa.

geologic processes: a scientific term used to : the process in which the spaces describe the internal and external forces that between loose particles are filled with a shape the physical makeup of the Earth. hardening or bonding agent. This is one form of lithification. : used by and other scientists to describe the timing and Colorado Plateau: a large uplifted plateau relationships between events that have roughly centered on the four corners region occurred during the . (Utah, , Colorado, and ) of the southwestern . : rock produced by the cooling and solidification of , either on or : the process by which overlying below the Earth’s surface. rock layers or sediments compress the spaces between underlying particles. This is one form : rock produced by the cooling of lithification. of magma deep beneath the Earth’s surface (also called plutonic rock). crater: a pit or hole in the ground created by an such as a volcanic eruption, or landslide: the downslope movement, under from the impact of a . gravity, of masses of and rock material; includes a wide range of ground movement, deposition: the geological process by which such as rockfall, slump, and debris slide. material is added to a or land mass.

lava: magma that emerges onto the surface of earthquake: the result of a sudden release of the Earth. energy in the Earth’s crust that creates seismic waves. lithification: the processes in which sediments become solid rock. erosion: the movement of weathered materials by natural processes. lithospheric plates: a massive, irregularly shaped slab of solid rock, generally composed : rock produced by molten lava of both continental and oceanic lithosphere that flows onto the surface of the Earth (also (also called tectonic plates); part of plate called ). tectonics. eyewitness: someone who has knowledge magma: molten rock deep within the Earth. about a dramatic event through seeing it firsthand.

Zion National Park, 2015 Erosion, Weathering, and Change 8 mesa: (Spanish and Portuguese for “”) an uplift: a geological process most often caused elevated area of land with a flat top and sides by which increases elevation. that are usually steep cliffs. It takes its name from its characteristic table-top shape and is volcano: an opening, or rupture, in a ’s larger than a butte. surface or crust, which allows hot, molten rock, ash and gases to escape from below the : rock that has undergone surface. change as a result of intense heat and pressure. weathering: of rocks, , normal fault: a break in the Earth where and their minerals by chemical or physical tension pulls rocks apart and one block slides processes. Chemical weathering involves a down relative to the other block. chemical change in at least some of the minerals within a rock. Mechanical paleoenvironment: the past environment of weathering involves physically breaking rocks an area during a given period of its history. into fragments without changing the chemical make-up of the minerals within it. plate tectonics: theory of geology that has been developed to explain the observed evidence for large scale motions of the Earth’s References lithosphere. Colorado Plateau Geosystems, Inc. Reconstructing the Ancient Earth, http:// plateau: also called a high or tableland, cpgeosystems.com/gallery.html. Last is an area of high elevation land, usually modified 2010. consisting of relatively flat .

Federal Agency. relative age: the age of a rock in comparison Seismic Sleuths: A teacher’s package for to other rocks. grades 7-12, 2nd Edition. D.C.: American Geophysical Union, 1995 rock cycle: interrelated sequence of events by which rocks are initially formed, altered, Hislop, Teresa, and Kirstin Reed. Topographic destroyed, and reformed as a result of maps, http://www.uen.org/Lessonplan/ magmatism, erosion, sedimentation (or preview?LPid=2209. Last modified 2002. deposition), lithification, and .

National Geographic. How was the scientist: in a broad sense is one engaging in a Grand Canyon formed? http://www. systematic activity to acquire knowledge. In a nationalgeographic.com/expeditions/ more restricted sense, a scientist is an lessons/07/g35/canyon35.html. Last individual who uses the scientific method. modified 2011.

sedimentary rock: rock produced from U.S. Geological Survey. What’s the difference particles deposited by wind, water, ice, or between weathering and erosion? http:// chemical reactions. geomaps.wr.usgs.gov/parks/misc/gweaero. html. Last modified 2014. sediment: finely divided solid material, ex: sand, , mud.

subduction: a geologic process in which one edge of a crustal plate descends below another.

thrust fault: occur in a compressional environment, where rocks are squeezed together and one block is forced upward (and possibly over) relative to another.

Zion National Park, 2015 Erosion, Weathering, and Change 9