Geography & Physiography

Overview

Emery County is an open book of physical geography. Spanning 4,472 square miles in east-central Utah, the county encompasses three distinct physiographic provinces—the High Plateaus, the Colorado Plateau, and the Basin and Range—each with its own climate, landforms, soils, and biotic communities. From the lush mountain valleys of the Manti-La Sal Range (reaching 10,743 feet at East Mountain) to the arid canyonlands and desert flats of the Green River basin (around 4,100 feet), Emery County exhibits a vertical span of approximately 6,643 feet—a gradient that creates microclimates and ecosystems as diverse as temperate forest and high desert scrub within a single county. Understanding Emery County begins with understanding its land: the geological uplift that shaped its mountains, the erosional processes that carved its canyons, the hydrologic systems that sustain its life, and the human communities that have made their home in this landscape.

1.1 County Boundaries & Setting

Emery County occupies a distinctive position in east-central Utah, bordered by Carbon County to the north, Grand County to the east, Wayne County to the south, Sevier County to the southwest, and Sanpete County to the west, with the northwestern corner touching Utah County. Its eastern boundary roughly follows the Green River corridor and the Tavaputs Plateau, while the western boundary encompasses much of the Wasatch Plateau crest. The county covers 4,472 square miles (approximately 11,582 square kilometers), making it one of Utah’s larger counties by area (UAGRC County Boundary Data, 2024; Utah Code § 17-16-6).

The physical geography of Emery County is not uniform; rather, the county straddles three major physiographic provinces that meet and intermingle across its territory. This position at the convergence of distinct geomorphic regions—the High Plateaus to the west, the Colorado Plateau to the south and east, and the Basin and Range to the north—gives Emery County its remarkable topographic and climatic diversity. Major settlements cluster in river valleys and mesa-top basins: Castle Dale, Ferron, and Huntington in the San Rafael Valley and surrounding basins; Emery, Cleveland, and Elmo on the upland margins; and Green River in the broad desert lowland near the confluence of the Green and Colorado rivers (USGS Topographic Data; Utah Division of Natural Resources, 2020).

1.2 Physiographic Provinces

Emery County straddles three of Utah’s major physiographic divisions, each contributing distinct landforms and processes. The High Plateaus province, which includes the Manti-La Sal Mountains, occupies the western portion of the county. This region is characterized by steep, heavily forested mountains with elevations exceeding 10,000 feet, deep stream valleys, and significant precipitation (Spencer & Chase, 1982). The highest point in Emery County is East Mountain (10,743 feet), located in the Manti-La Sal Range.

The Colorado Plateau province dominates the central and southern portions of the county. This vast region—covering much of the Four Corners area—is defined by horizontal or gently tilted sedimentary rock layers that have been deeply dissected by canyons and rivers. The San Rafael Swell, a broad anticlinal uplift, occupies much of the county’s central territory. The Swell exposes colorful sequences of Paleozoic and Mesozoic rocks in dramatic cliffs and canyons: the red walls of the Wingate Sandstone, the pale domes of the Navajo Sandstone, and the darker cap rocks of younger formations. This landscape is typically arid, with sparse vegetation adapted to low precipitation and high temperature fluctuations.

The Basin and Range province occupies portions of the northern and northeastern portions of Emery County, particularly around the Green River valley. This province is characterized by elongated mountain ranges separated by wide basins, a product of crustal extension that has been ongoing for millions of years. In Emery County, the Basin and Range character is less pronounced than in western Utah, but its influence is visible in the tilted mountain blocks and intervening alluvial basins (Hintze & Kowallis, 2009; Doelling, 2004).

1.3 Major Landforms & Relief

Emery County’s topography is dramatically varied, with relief—the difference in elevation between the highest and lowest points—exceeding 6,600 feet. The county’s highest elevations occur in the Manti-La Sal Mountains and Price River Mountain range along the western margin, where forest-capped ridges and peaks reach above 10,000 feet. The lowest elevations occur in the Green River valley and along drainages in the south and east, where elevations approach 4,100 feet at the Green River’s confluence with the Colorado River (USGS DEM; National Elevation Dataset).

Between these extremes, the landscape is organized into several major topographic units. The High Plateaus (or Plateaus section of the Rocky Mountain province) in the west consist of uplifted mesa-like surfaces and deeply incised stream valleys. Elevations on these plateau surfaces typically range from 8,000 to 10,000 feet, and summer moisture is sufficient to support ponderosa pine, Douglas-fir, and aspen forests. The San Rafael Swell in the central county is a large anticlinal fold—essentially a broad arch of rock layers—that rises above surrounding terrain and has been carved by erosion into a landscape of ridges, cliffs, and canyons. The Book Cliffs and Roan Plateau in the north form a prominent escarpment trending northeast-southwest, separating the upland plateau surfaces from lower basins. The Green River valley and surrounding lowlands in the east and south form wide, open basins where elevation is typically 4,000 to 5,500 feet and the climate is arid (Doelling, 2004; Utah Geological Survey, 2020).

1.4 Drainage Basins & Watersheds

Emery County’s surface water is organized into several major drainage basins, each with its own hydrologic characteristics. The Green River—one of the Colorado River’s major tributaries—drains much of the eastern half of the county. Originating in the Wind River Mountains of Wyoming, the Green River enters Emery County from the north and flows southeastward, carving the deep canyons of Desolation Canyon and Gray Canyon through the Book Cliffs and into the Colorado Plateau proper. The Green River receives water from numerous tributaries within the county, including the White River and Price River from the north and west (USGS Water Resources; Utah Division of Water Resources, 2019).

The Price River, a major tributary of the Green River, drains the western uplands and flows northeastward through Castle Dale and Huntington before joining the Green River. The Price River’s headwaters lie in the Wasatch and Manti-La Sal ranges at elevations above 10,000 feet, and the river descends nearly 6,000 feet over its course within and upstream of the county. This steep gradient and high elevations in its drainage basin give the Price River a more robust seasonal flow than lowland streams in the region (USGS, Price River Basin; Utah State Engineers Office, 2018).

In the south and southeast, the San Rafael River—which drains the San Rafael Swell and surrounding plateaus—flows into the Colorado River. The San Rafael Swell’s interior is dissected by slot canyons and washes that concentrate runoff during rainfall events. The Fremont River, another Colorado River tributary, drains the southern portions of Emery County and flows through the scenic canyonlands near Caineville and along the boundary with Wayne County (Utah DNR, Watershed Divisions; USGS Hydrologic Data).

Emery County also contains numerous smaller drainages and ephemeral washes that carry water during storms. These feature prominently in the county’s geomorphology, particularly in the arid south and east, where intense rainfall events can trigger flash flooding in narrow canyons (USGS, Flash Flood Information; Utah State Geologist, 2015).

1.5 Elevation Gradient & Hypsometry

The elevation profile of Emery County reflects its position at the convergence of three physiographic provinces and creates striking microclimatic variation. Hypsometry—the statistical distribution of elevation across an area—reveals that Emery County is divided into distinct elevational tiers, each with characteristic climate, vegetation, and soils.

The highest tier, above 9,000 feet, comprises the summits and upper slopes of the Manti-La Sal Range, Price River Mountain, and the high plateaus. This zone typically experiences long, cold winters with significant snowfall; short summers; and substantial annual precipitation (30–50 inches in places). The landscape is dominated by spruce, fir, and aspen forest, with alpine meadows at the highest elevations. This zone occupies roughly 5–8 percent of the county’s area (National Elevation Dataset; USGS).

The mid-elevational tier, between 7,000 and 9,000 feet, includes the majority of the Manti-La Sal Mountains’ flanks, the Price Plateau, and portions of the Book Cliffs. This zone experiences moderate winters, mild summers, and precipitation in the 15–30 inches per year range, supporting ponderosa pine, Douglas-fir, and aspen forest, with some areas of pinyon-juniper woodland at lower margins. This tier comprises roughly 10–15 percent of the county’s area.

The intermediate tier, between 5,000 and 7,000 feet, encompasses the San Rafael Swell’s rim, much of the central plateaus, and the foothills flanking the uplands. This zone is semi-arid, with annual precipitation ranging from 10 to 20 inches, and supports a mix of pinyon-juniper woodland, sagebrush scrub, and scattered ponderosa pine. This is a critical transition zone between the humid uplands and the arid lowlands. Roughly 20–25 percent of the county’s area falls within this tier.

The lowest tier, below 5,000 feet, includes the Green River valley, much of the lowland basins surrounding settlements, and the deeply incised canyons of the major rivers. This zone is arid, receiving less than 10 inches of annual precipitation in most areas, and is dominated by salt desert shrub, Fremont cottonwood riparian woodland, and four-wing saltbush scrub. This tier comprises roughly 50–60 percent of the county’s area, reflecting the reality that much of Emery County is low desert (Utah Climate Center; National Elevation Dataset).

1.6 Structural Geology

The large-scale structure of Emery County is defined by a series of tilted mountain blocks, folded rock layers, and faults that are the product of millions of years of crustal deformation. The county’s position at the margin between the stable Colorado Plateau and the deformed Rocky Mountain province means that it experiences both the relatively gentle folding of the Plateau and the more intense faulting and uplift of the Mountains (Hintze & Kowallis, 2009).

The Manti-La Sal Mountains, which form the western margin of the county, are a block-tilted mountain range with its steeper limb facing west and a gentler dip to the east. This structure was created by Laramide-age (roughly 80 to 55 million years ago) thrust faulting and subsequent uplift. The range exposes thick sequences of Paleozoic metamorphic and igneous rocks, interlayered with sedimentary strata (Doelling, 2004).

The San Rafael Swell, occupying much of the central county, is a broad anticlinal fold—an upright, arch-like fold in rock layers. The Swell formed primarily during the Laramide orogeny and has been a locus of persistent uplift throughout the Cenozoic. Its southern limb dips steeply southward, while its northern limb dips gently northward. The Swell’s interior contains spectacularly exposed Paleozoic and Mesozoic sedimentary rocks, with younger layers folded around the uplift’s core. The Swell is bounded on its east and south by major faults—the San Rafael fault on the south and east—along which significant displacement has occurred (Spencer & Chase, 1982; Utah Geological Survey, 2020).

The Book Cliffs, which trend northeast-southwest across the northern part of the county, represent the southern flank of the Roan Plateau (or Tavaputs Plateau). This is a monoclinal structure—a one-sided fold where rock layers dip steeply in one direction over a relatively short distance. The monocline brings younger, softer rocks (Cretaceous shales and siltstones) abruptly over older, more resistant rocks (Paleozoic and lower Mesozoic formations), creating the distinctive cliff-face landscape (USGS Geologic Map, Utah).

Throughout Emery County, numerous smaller faults cut the rock layers, often with vertical displacements ranging from a few feet to hundreds of feet. These faults are typically high-angle, normal faults that reflect the extensional (stretching) stress regime that has affected the region, particularly since the end of the Laramide orogeny. The faults influence groundwater movement, mineral deposits, and the detailed topography visible in hiking and field exploration (Utah Geological Survey, Fault Database; USGS Structural Geology).

1.7 Geomorphology of the San Rafael Swell

The San Rafael Swell occupies roughly the central third of Emery County and is one of Utah’s most distinctive and scenic geomorphic features. The Swell’s geology—a large anticlinal fold—drives its geomorphology: as rock layers are folded upward and then eroded, the landscape becomes a complex assemblage of ridges, cliffs, and deeply incised drainages that create a maze-like topography (Spencer & Chase, 1982).

The Swell’s exterior (its margins) is ringed by steep cliffs where erosion-resistant rock formations (particularly Permian and Carboniferous sandstones and limestones) form natural barriers. These cliffs are hundreds of feet tall in places and include formations such as the Wingate Sandstone (Jurassic, striking red-orange color) and the Navajo Sandstone (cream-colored, massive, Jurassic age). Between the outer cliffs and the Swell’s interior lie a series of ridges and valleys carved by relatively young rivers and tributaries. Within the Swell’s interior, the landscape is dominated by slot canyons, narrow washes, and sculpted buttes and hoodoos where softer Jurassic and Cretaceous shale layers have been stripped away by flowing water, leaving behind the harder interbedded sandstones as ridges (Doelling, 2004; Utah Geological Survey, 2020).

The Swell’s drainage systems flow toward the major rivers—the Price River to the west, the Green River to the east, and the San Rafael River to the south. Flash flooding during heavy summer thunderstorms can be significant in the Swell’s canyons, and narrow canyon passages can be hazardous during rainfall events. Alluvial fans—fan-shaped deposits of sediment—are common where tributary drainages exit the Swell’s interior and meet the larger river valleys, representing zones of sediment deposition after energy-intensive flooding events (USGS, Alluvial Systems; Utah State Geologist, 2015).

The Swell has been a focus of oil and natural gas exploration and development since the early 20th century, and its subsurface geology is relatively well-mapped through thousands of drill holes and seismic surveys. This has made the Swell an important natural laboratory for petroleum geology and subsurface structural interpretation (Utah Geological Survey, Oil and Gas Assessments, 2018).

1.8 Soil Orders & Geochemistry

Emery County’s soils are diverse, reflecting the county’s varied elevation, precipitation, parent rock type, and vegetation patterns. Soil formation is controlled by five major factors: parent material (the rock or sediment from which soil is weathered), climate, organisms (including plants, animals, and microorganisms), topography, and time. In Emery County, the steep precipitation gradient from humid mountains to arid lowlands creates a strong west-to-east trend in soil types (NRCS Soil Survey, Emery County; USDA, Official Soil Series).

In the high-elevation forests of the Manti-La Sal Mountains, Mollisols and Alfisols predominate. Mollisols are dark-colored soils rich in organic matter, typically formed under grassland or mixed vegetation; Alfisols are forest soils with moderate weathering and distinct clay layers. These soils are relatively young (geologically speaking) because high elevation, steep slopes, and strong water erosion limit the time available for soil formation. The typical profile includes a dark surface horizon rich in organic matter (humus from decaying leaves and roots), a subsurface zone where clay and iron oxides have accumulated (the B horizon or subsoil), and weathered parent material below (NRCS Soil Survey; USDA, Soil Taxonomy).

At intermediate elevations (5,000–8,000 feet) in the semi-arid pinyon-juniper and ponderosa pine zones, Mollisols, Alfisols, and Aridisols are common. Aridisols are soils of arid and semi-arid regions, typically light-colored, with low organic matter content and often an accumulation of calcium carbonate salts in subsurface layers. These soils form more slowly than forest soils because vegetation is sparser and weathering is slower under arid climates (NRCS Soil Survey; Utah State Soil Scientists).

In the arid lowlands (below 5,000 feet), Aridisols and Entisols dominate. Entisols are young, underdeveloped soils with little profile development—often seen in active floodplains, dune fields, and other recently formed surfaces. In the Green River valley and similar lowland basins, salts and other minerals often accumulate at the soil surface or in shallow subsurface layers, a process called salinization. This occurs in areas with high evaporation, shallow groundwater, and limited leaching. Soil salinity can be toxic to plants, and management of salt-affected soils is an important land-use consideration in the county’s agricultural areas (NRCS Soil Survey, Emery County; USGS Water Quality Data).

Parent material strongly influences soil characteristics. Soils derived from granite and quartzite (in the Manti-La Sal Range) tend to be coarser (more sandy) and less naturally fertile than soils developed from limestone and shale. Limestone and shale weathering produces clayey soils that are often more fertile but more prone to compaction and reduced permeability. In the San Rafael Swell and surrounding regions, soils derived from sandstone parent materials are typically sandy and well-drained, while soils derived from shale are fine-grained, sticky when wet, and prone to erosion (USDA, Soil Taxonomy; NRCS, Soil Survey Manual).

1.9 Karst & Cave Systems

Karst landscapes—terrain characterized by sinkholes, caves, springs, and underground rivers—develop where soluble rocks (primarily limestone and gypsum) are present and rainfall or other water sources allow dissolution of the rock. Emery County contains significant karst features, particularly in areas where Mississippian and Pennsylvanian limestone formations are exposed (Utah Geological Survey, Cave and Karst Database; USGS, Karst Features).

The most famous karst features in Emery County are the cave systems, particularly the major caves of the San Rafael Swell region. Sinkhole formation occurs when water dissolves limestone along joint patterns (cracks in the rock), creating voids underground that eventually collapse to form surface depressions. Sinkholes range from a few feet to over 100 feet in depth and diameter. Once formed, sinkholes may collect water or remain dry, depending on local groundwater levels and climate patterns. Some sinkhole lakes in the Swell are permanent features that attract wildlife and have been important water sources for human use (Utah State Geologist, Sinkhole Inventory; USGS, Geomorphology).

Caves form through similar processes: water percolating through fractured limestone dissolves the rock along weak zones, gradually enlarging solution passages until they become large enough for humans to enter. Inside caves, continued water flow deposits minerals in colorful formations—stalactites (hanging from ceilings), stalagmites (rising from floors), flowstone (sheet-like deposits), and columns (where stalactites and stalagmites join). Emery County’s caves have been used by humans for thousands of years, from ancient Fremont people to modern-day recreational cavers. The caves maintain relatively constant temperatures year-round (typically 40–50 degrees Fahrenheit) and often host colonies of bats and other cave-adapted organisms (Utah Geological Survey, Cave Inventory; National Park Service, Cave Management).

Springs are another important karst feature, resulting from groundwater flowing through limestone or other rock until it reaches the surface. Numerous springs occur in Emery County, particularly where permeable rock formations (sandstone) are underlain by less permeable layers (shale or clay). Springs may be thermal (heated by geothermal energy from depth) or cold (reflecting the temperature of shallow groundwater). Springs have been crucial water sources for Emery County settlements and wildlife throughout human history (USGS, Spring Inventory; Utah Division of Water Resources, Water Rights Database).

1.10 Aeolian Landforms

Aeolian landforms—features created by wind erosion and deposition—are prominent in the arid and semi-arid portions of Emery County. Wind-carved rocks (ventifacts), sand dunes, and dust-derived deposits (loess) are all present, particularly in the arid lowlands and the San Rafael Swell’s interior (USGS, Aeolian Geology; Utah Geological Survey, Landscape Evolution).

Sand dunes occur in several locations within the county, most notably in the San Rafael Swell’s interior and along portions of the Green River valley. These dunes are fed by sand eroded from Jurassic sandstone formations (Navajo and Entrada Sandstones) and transported by prevailing winds. Many of the Swell’s interior dunes are stabilized by vegetation (particularly saltbush and other desert shrubs) and are therefore not actively migrating, but during drought periods or in areas with reduced vegetation cover, sand movement can be significant. The dunes range from small sand sheets to barchan dunes (crescent-shaped) and transverse dunes (linear, perpendicular to wind direction) (USGS, Sand Dunes; Utah Geological Survey, 2020).

Desert pavement—a surface lag of pebbles and stones left behind after finer particles have been deflated (removed by wind) or have sunk into the soil—is characteristic of many arid regions in Emery County, particularly on stable surfaces of Quaternary age (less than 2.6 million years old but often much younger). Desert pavement protects underlying finer soil from further wind erosion and is an important indicator of landscape age and stability. Disturbance of desert pavement by off-road vehicle use or other impacts can trigger erosion and dust production (USGS, Desert Pavement; Bureau of Land Management, Environmental Assessments).

Loess—silt-sized sediment deposited by wind—is less prominent in Emery County than in northern Utah or the Great Plains, but wind-derived silt is present in some soils and has contributed to soil formation, particularly in areas downwind of major river valleys where glacial flour-sized sediment (very fine silt) is available for wind transport (USDA, Soil Taxonomy; USGS, Loess Distribution).

1.11 Paleoflood Terraces & Alluvial Fans

Emery County’s major river valleys—particularly along the Green River, Price River, and San Rafael River—are characterized by terraced landscapes where multiple generations of alluvial deposits (sediment deposited by flowing water) have been preserved at different elevations. These terraces represent former floodplains that have been cut into by subsequent river erosion, creating a “stair-step” topography of abandoned floodplain surfaces (USGS, Terraces; Utah State Geologist, 2015).

Paleoflood deposits and terraces provide evidence of past flood events and climatic changes. High terraces—far above the current river level—indicate times when river discharge was higher, possibly reflecting a wetter climate or greater upstream snowmelt. Multiple terrace levels in a single river valley indicate multiple cycles of aggradation (sediment deposition) and incision (erosion). These terrace sequences are valuable for paleoclimatic interpretation and for hazard assessment, as they indicate the maximum flood levels that have occurred in recorded and pre-recorded time (USGS, Paleofloods; Utah State Engineer, Flood Hazard Assessment).

Alluvial fans—cone-shaped or fan-shaped deposits of sediment—occur where steep tributary valleys meet broader main valleys and stream gradient decreases dramatically. The loss of carrying capacity caused by this decrease in slope causes the stream to deposit its sediment load as a fan-shaped accumulation. Fans are common throughout Emery County, particularly along the margins of the San Rafael Swell and in canyons where tributaries deliver sediment to major rivers. Active fans—where sediment is currently being transported and deposited—can shift their deposition pathways over time, creating hazards for structures or agricultural land in their paths. Older, stabilized fans become incorporated into the landscape and may be used for settlement or agriculture (USGS, Alluvial Fans; Bureau of Land Management, Geomorphology Studies).

1.12 Geospatial Datasets & Remote Sensing

Modern geospatial technology provides powerful tools for analyzing and visualizing Emery County’s geography. Digital elevation models (DEMs)—gridded datasets of elevation values derived from satellite or airborne lidar measurements—allow detailed analysis of topography without field surveys. The USGS 1-meter resolution National Elevation Dataset (NED) provides vertical accuracy of approximately 1 meter in most areas and has become a standard for hydrologic modeling, landslide hazard assessment, and visibility analysis. Higher-resolution lidar datasets (covering portions of the county at 1-meter or finer resolution) reveal fine-scale topographic features such as scarp, gullies, and debris flows (USGS National Elevation Dataset; USGS 3DEP Program).

Multispectral satellite imagery from Landsat, Sentinel-2, and high-resolution commercial satellites (such as WorldView or Maxar) allows classification of vegetation, mapping of geological formations, and monitoring of landscape changes over time. False-color composites using near-infrared, red, and green bands can effectively distinguish vegetation types, water bodies, and exposed rock/soil surfaces. Time-series analysis of satellite data spanning decades reveals trends in vegetation health, fire scars, erosion, and land use (USGS, Landsat Data; European Commission, Copernicus Sentinel Hub).

Geological mapping has been conducted at 1:100,000 and 1:250,000 scales by the Utah Geological Survey and the USGS, with digital versions available through the Utah Geological Survey’s Geology Portal. These maps show the distribution and age of rock formations, faults, and mineral deposits, and they serve as the foundation for understanding Emery County’s geological structure (Utah Geological Survey, Geologic Maps; USGS Geologic Maps).

GIS (Geographic Information System) analysis platforms such as ArcGIS, QGIS, and cloud-based systems (Google Earth Engine, ESRI ArcGIS Online) enable integration of multiple geospatial datasets for complex analysis: hydrologic flow analysis, viewshed analysis (visibility from specific locations), habitat suitability modeling, and hazard mapping. These tools are increasingly used by land management agencies, researchers, and planners working in Emery County (USGS, GIS Data Repository; National Map Viewer; BLM, Landscape Approaches).

Engagement Features

Did You Know?

Three Provinces in One County. Emery County straddles three major physiographic provinces—the High Plateaus, the Colorado Plateau, and the Basin and Range. Few places in North America contain such dramatic physiographic contrast within a single county boundary.

By the Numbers—Elevation Span. The vertical distance from Emery County’s highest point (East Mountain at 10,743 feet) to its lowest point (Green River valley at approximately 4,100 feet) is about 6,643 feet. This elevation span creates diverse climates and ecosystems—from mountain forests to high deserts—all within a few hours’ drive.

Hidden Underground. The San Rafael Swell contains extensive cave systems and countless sinkholes formed by the dissolution of limestone. Water percolating through the rock over millions of years has carved a hidden landscape beneath the Swell’s surface.

Desert Pavement Puzzle. In Emery County’s desert regions, you’ll find “desert pavement”—a mosaic of pebbles and stones that covers older, more finely textured soil beneath. This protective layer forms over thousands of years as wind deflates finer particles and gravity winnows materials. Disturbing desert pavement triggers erosion.

Family Activity

Activity 1: Build an Elevation Profile. Use a topographic map or Google Earth to identify Emery County’s highest and lowest points. Draw a simple graph with distance on the x-axis (west to east across the county) and elevation on the y-axis. Plot major landmarks (East Mountain, San Rafael Swell, Green River) and sketch the profile. Compare your profile to the actual terrain by looking at satellite imagery or visiting in person. How does the landscape you see match your profile?

Activity 2: Soil Detective. Dig a small hole in different locations around your home or a park in Emery County (with permission). Observe the soil’s color, texture (sandy vs. clay), and smell. Is there organic matter (dark, decomposing leaves)? Try rubbing a bit of moist soil between your fingers—does it feel gritty (sandy) or sticky (clayey)? Use your observations to predict which major soil order you’ve found. What does the parent material look like?

Activity 3: Map Your Watershed. Find out which river or creek is in your neighborhood’s watershed. Use a topographic map or an online watershed mapper (such as the USGS StreamStats tool) to trace the drainage patterns around your home. Where does water from your property flow? What larger river does it eventually reach? How far does water travel before reaching the Green River or Colorado River?

Youth Scavenger Hunt

Explore Emery County’s geography with these challenges:

1. Spot the Reef. Visit a location on the San Rafael Swell’s rim or margin and look for exposed rock layers that are tilted or bent. These are folded rocks formed by the anticlinal uplift of the Swell. Sketch or photograph the rock layers and label the angle of tilt you observe.

2. Measure Relief. Using a topographic map or elevation data, find the highest and lowest elevations within a 1-mile radius of a town like Huntington or Castle Dale. Calculate the relief (difference) and describe the landforms at the high and low points. Is relief greater near mountains or in lowlands?

3. Find Desert Pavement. In an arid part of the county (Swell interior, Green River valley), locate a patch of desert pavement. Photograph it and examine the stones. Are they all the same size, or mixed? What finer material might lie beneath the pavement?

4. Creek to River. Follow a small creek or wash from its starting point (in a canyon or tributary) toward a major river. How does the creek’s character change as it descends? Does it pick up tributaries? Does it flow year-round or only after storms?

5. Rock Layers. Find a roadcut or canyon wall where you can see multiple rock layers (strata). Count the layers and estimate their thicknesses. Are the layers the same age, or different? Use color and grain size to distinguish them.

6. Soil Swap. Collect soil samples from three different elevations (e.g., 4,000 feet, 7,000 feet, 10,000 feet). Place each sample in a glass of water and shake well. Watch as particles settle. Which sample settles fastest (coarser sand)? Which has the most fine silt or clay remaining suspended? What does this tell you about weathering and soil development at different elevations?

7. Sinkhole Search. In the San Rafael Swell, look for sinkholes—roughly circular depressions in the landscape. How deep are they? Is there water, vegetation, or rocks visible inside? Are they aligned in rows (suggesting they follow a fault or joint), or scattered randomly?

8. Benchmark Hunter. USGS and National Geodetic Survey benchmarks are small brass tablets or marks set into stone to record precise elevations. Search for one in your town using the National Geodetic Survey’s datasheet tool online. If you find it, photograph it and record the elevation listed on the marker.

Field Trip

Trip 1: San Rafael Swell Half-Day Tour (2–3 hours). Start in Castle Dale and drive south into the San Rafael Swell via Utah State Route 10 or local roads (check road conditions beforehand). Stop at scenic overlooks such as the Goblin Valley State Park area or along various pullouts to observe the Swell’s dramatic stratigraphy—red Wingate Sandstone, cream Navajo Sandstone, and darker cap rocks. Look for erosional features: slot canyons, hoodoos, and natural bridges carved by water. Return via the same route. Bring water and sun protection; roads may be rough in places.

Trip 2: Elevation Transect Full-Day Tour (6–8 hours). Begin at the Green River (elevation ~4,100 feet) and drive westward into higher elevations, stopping at representative sites along the way: the Book Cliffs (5,000–6,000 feet), the Castle Dale area (6,500 feet), the Price River canyon (7,000+ feet), and the high plateaus above Huntington or Joes Valley (9,000+ feet). At each stop, observe and photograph vegetation, geology, soil characteristics, and landscape. Compare climate indicators (weather station data, vegetation type) across the elevational range. A good route: U.S. Route 6 from Green River to Castle Dale to Price, with detours into canyons and plateaus as time permits.

Trip 3: Book Cliffs Escarpment Half-Day Tour (2–3 hours). Drive or hike along the base or top of the Book Cliffs, which form the northern boundary of much of Emery County. The cliffs expose the monocline—rock layers dipping steeply northward—and offer panoramic views of the Tavaputs Plateau above and the lowlands below. Access points include areas near Sunnyside and Price. Bring binoculars for wildlife (bighorn sheep, raptors) and a camera for the expansive vistas.

Sources

Copernicus Sentinel Hub. (2024). Sentinel-2 multispectral satellite imagery. Retrieved from https://scihub.copernicus.eu/

Doelling, H. H. (2004). Geologic map of Emery County, Utah. Utah Geological Survey Map 205, 1:250,000 scale.

European Commission. (2024). Copernicus data access portal. https://scihub.copernicus.eu/

Hintze, L. F., & Kowallis, B. J. (2009). Geologic history of Utah (3rd ed.). Brigham Young University Geology Studies, Special Publication 9.

National Park Service. (2015). Cave management guidelines. National Park Service Technical Report.

NRCS (Natural Resources Conservation Service). (2020). Soil survey of Emery County, Utah. USDA Soil Survey Database.

Spencer, J. E., & Chase, G. W. (1982). Geology and ore deposits of the Mercur mining district, Utah. Utah Geological and Mineral Survey Bulletin 116. (Referenced for structural geology and Laramide context.)

USDA (U.S. Department of Agriculture). (2020). Official soil series descriptions and soil taxonomy. USDA Soil and Plant Systems Division.

USGS (U.S. Geological Survey). (2020). National Elevation Dataset (NED). 1-meter resolution digital elevation model. Retrieved from https://www.usgs.gov/3dep/

USGS (U.S. Geological Survey). (2021). Landsat 8/9 satellite imagery archive. Retrieved from https://landsat.usgs.gov/

USGS (U.S. Geological Survey). (2022). Water resources of Utah. USGS Water Resources Data.

USGS (U.S. Geological Survey). (2023). Geologic map of Utah. 1:500,000 scale. Reston, VA: USGS.

Utah Division of Natural Resources. (2020). Water rights and watershed boundaries in Utah. State of Utah Water Rights Database.

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