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Home , Bear River Range, Book Cliffs, Colorado Plateau, Geology of Utah, San Rafael Swell, Sevier Lake

106 RANGELANDS 14(2), April 1992

Physiographic Provinces and Surface of Roger E. Banner

The physicalfeatures of Utah provide some ofthe most most half of the state falls within the beautifulscenery anywhere. Utah is a land of stark con- Province, which is divided into three primary sections in trast with high , , ridges, uplands, Utah: the , Canyonlands, and High Plateaus. plains, basins, and . Elevations rangefrom a low Several subsections are recognized within these three of 2,350 ft above sea level along the Beaver Dam Moun- divisions. tains in extreme southwestern Utah to 13,528 ft in the (Murphy 1981). Murphy (1989b) pre- sents an informative discussion of these features, from which I have drawn much of the content of this paper. Table 1 is a reference to geologic eras, periods, and

Table 1. Eras,periods, and epochsthrough geologic time(adapted from Stokes 1986).

Millions of Millions of Years Ago Years Duration Geologic Time Begin End Era 66 —— 66 QuartenaryPeriod 2 —— 2 HoloceneEpoch .011 —— .011 PleistoceneEpoch 2 .011 1.989 Period 66 2 64 Epoch 5 2 3 Epoch 24 5 19 Epoch 37 24 13 Epoch 58 37 21 66 58 8 Epoch Wah Wah Mountains across Pine Great MesozoicEra 245 66 179 , Basin Section of the Basin and Province, Beaver Utah. CretaceousPeriod 144 66 78 Range County, Jurasic Period 208 144 64 -The Section Period 245 208 37 The Great Basin is a region of north-south aligned PaleozoicEra 570 245 325 mountainranges separated by wide, sediment-filled val- PermianPeriod 286 245 41 with internal The Period 320 286 34 leys mostly drainage. ranges were formed and were later modified ero- MississippianPeriod 360 320 40 by faulting by DevonianPeriod 408 360 48 sion. Era , dolomites, shales, and Period 438 408 30 sandstones are the dominantoutcrops along the normal OrdovicianPeriod 505 438 67 escarpments (Moyle1981). The valleys are filled with CambrianPeriod 570 505 65 recent sediments from the Cenozoic Era (Ash 1981). PrecambrianTime 4,600 570 4,000 Largealluvial fans have formedat canyonmouths and in some areas the mountain ranges have eroded to the epochs providing some additional perspective on time extent that they are all but buried by deposits of fan that may be helpful in the discussions that follow. material. Four of the in major physiographic provinces North The Pine Valley and Bull Valley Mountains of south- America extend into the wide of Utah, providing variety western Utahare east-west mountainranges thatserve as topography.The Great Basin Section of the Basin and a divide between the Great Basin and the Colorado Pla- Province western Range encompasses Utah and the teau. Extreme southwestern Utah is part of the Colorado Snake River- Province dips into a small River of drainage system, not part of the interior drainage area extreme northwestern Utah. The system of the Great Basin. The terrain of the area is not and the Uinta Mountains, in northern and northeastern different than Great Basin terrain and is are greatly usually Utah, recognized subsectionsof the Middle Rocky mapped as part of the Great Basin. Mountain Section of the Rocky Mountain Province. Al- The Great Salt is a remnant of , the Theauthor is Assistant Professorand ExtensionSpecialist, RangeScience largest Quartenary (Cenozoic Era, Quartenary Period, Department, , Logan,Utah 84322-5230. RANGELANDS 14(2), April1992

Pleistocene Epoch) lake in western North America. Lake Fault. The eastern flank rises much moregently. Like the Bonneville coveredabout 20,000 square miles and was Uinta Mountains,the Wasatch Range has a core of very more than 1,000ft deep in the area of the presentGreat old ( Era) , , and Salt Lake. The Lake Bonnevilleshorelines apparent today overlain by old ( Era) sandstones, shales, mud- are a result of at least10 major risesand falls of lake level stones, and limestones (Moyle 1981). Locally, more over the last 100,000 years (Hintze 1975). The other ter- recent (CenozoicEra) conglomerates and shales, inter- minal lake of the Great Basin in Utah, and also a former spersed with volcanictuffs and breccias, form the surface part of Lake Bonneville, is . Now it is a playa layers of strata (Moyle 1981). which is dry most of the time. It is located in Millard Province County, iii west central Utah (Murphy 1989a). Uinta Basin. The Uinta Basin Section of the Colorado Rocky Mountain Province-Middle RockyMountain Section Plateau Province is a synclinal as well as topographic Ulnta Mountains. The Uinta Mountains are an east- basin with an east-west axis running nearthe south flank west mountainrange about 150 miles long and 30 miles of the Uinta Mountains. The highestelevations are around wide. They were formed by anticlinal uplifting with sedi- 9,000 ft at the southern boundary along the top of the mentary units outcropping on all sides and dipping out- and the lowest elevations at the basin floor ward. The core of these mountains is very old (Precam- nearVernal are about 5,000 ft. The basincontains 20,000 brian Era) and the outcrops on the flanks are to 25,000 ft of marineand continentallimestones, shales, ancient(Paleozoic and Mesozoic Eras) Iimestones, shales, and sandstones of old (Paleozoic Era) to recent (Cenoz- and sandstones (Hintze1975, Moyle1981, Murphy198gb). oic Era) age (Moyle 1981). The Green River shales of The Uinta Mountainswere extensively glaciatedin recent recent (CenozoicEra) origin contain vast depositsof oil ( Epoch, Quartenary Period, Cenozoic Era) shale and other hydrocarbons. Although the basin is timesand glacial features dominatethe landscape. Glaci- ation created many examples of horns, aretes, cirques, and glacial troughs. Subsequent depositionof moraine by ice and glacial-melt water has created many small high-mountainlakes across the region.

View to the north down Willow Creek in me oo - ..._, Basin Section of the Colorado Plateau Province, Grand County, Utah. gently rolling for the most part, there are areas like the Book and Roan Cliffs that have eroded and been cut by View of Wasatch Mountains from a point in the BearRiver Range deep ravines and spectacular canyons. nearHardware Ranch, Middle RockyMountain Sectionof the Rocky Canyonlands. The Canyonlands Section of the Colo- Mountain Cache Utah. Province, County, rado Plateau Provinceencompasses thesoutheast quar- Wasatch and Bear River Ranges. The Wasatch and ter of the state. It is dominated by essentiallyhorizontally BearRiver Ranges are similar exceptin extent. The Bear lying old (Paleozoic and MesozoicEra) to recent (Ceno- River Range is a relativelysmall mountainrange of similar zoic Era) sandstones and shales with minor amountsof to the Wasatch Range, located between (Moyle 1981). Recent (CenozoicEra) igneous and . The Wasatch Range is a intrusionsof monzonites, syenites, and diorites form the north-south oriented mountain rangethat extends from domed highlands of the Henry, LaSal and Abajo Moun- south to Salt Creek east of Nephi. The tains (Moyle 1981). The Monument and Circle Cliffs western flank is very steep and relatively straight as a uplifts and are predominantly arched result of displacement along the still active Wasatch and folded rock layers. The Great Sage Plain, south ofthe 108 RANGELANDS 14(2), April 1992

Era) , andesite lava flows, and glacial deposits. Faulting generally marks the boundaries of this section with the Great Basin Section of the Basin and Range Province and the Section of the Colorado Plateau Province. These Boundaries are marked with colorful such as Cedar Breaks and Bryce

San RafaelSwell, Canyonlands Section of the Colorado Plateau Province,Emery County, Utah. LaSal Mountains, is an unusually wide and flat region unlike the surrounding area of deeply cut canyons and intrusive mountainranges (Murphy 1989b). The Kaipar- owits Plateau appears to be transitional between the Canyonlandsand the High Plateaus Sections, but the Cedar Breaks, High Plateaus Section of the Colorado Plateau marginalcliffs are erosionboundaries ratherthanfaulted Province, Iron County, Utah. boundaries like those that define the southern High Pla- Canyon. The southern boundary ofthis section is marked teaus (Murphy 198gb). The Lowlands, by a series of cliffs known as the . They include the Chocolate Cliffs, Vermillion Cliffs, White Cliffs, Gray Cliffs, , and Black Cliffs. Snake River-Columbia Plateau Province The Snake River-Columbia Plateau Province makes a very limited entry into Utah in the extreme northwest corner of the state. This small area includes one small basin drainingnorth from the Goose CreekMountains in Boxelder County to the Snake, and eventually, Columbia Rivers.The GooseCreek Mountains are composedof old (Paleozoic Era) to recent (Cenozoic Era) sedimentary rocks sometimes capped with volcanic ash and lava flows. Literature Cited Ash, S.R. 1981. Tectonic features. pp. 22-23. In: D.C. Greer, K.D. Gurgel, W.L. Wahlquist, H.A. Christy and G.B. Peterson. 1981. Atlas ofUtah. Weber StateCoIl, and Brigham Young Univ. Press, Provo, Utah. 300 p. Hlntze,L.F. 1975. Geological Highway Mapof Utah. Brigham Young Univ. Geol. Stud. Spec.Pub. 3. (Reprinted1984). Brigham Young MancosShale Lowlands along Interstate 70and south of the Book Utah. Plateau Province, Univ., Provo, Cliffs, Canyonlands Section of the Colorado R.W. 1981. Surfacegeology. pp. 20-21. In: D.C. Greer, K.D. Grand Utah. Moyle, County, Gurgel, W.L. Wahlquist, H.A. Christy and G.B. Peterson. 1981. south of the and east of the High Plateaus, Atlasof Utah. WeberState Coil. and Brigham YoungUniv. Press, in weaker rocks. Provo, Utah. 300 p. form a fairly flat region developed Murphy, D.R. 1981. Elevationand relief. pp. 18-19. In: D.C. Greer, High Plateaus. The High Plateaus Section ofthe Colo- K.D. Gurgel, W.L. Wahiquist, H.A. Christy and G.B. Peterson. rado Plateau Province consists of north-south oriented 1981. Atlas of Utah. Weber State Coil, and Brigham Young Univ. Press, Provo,Utah. 300. fault blocks of old (Mesozoic Era) to recent (Cenozoic Era) sandstones and shales capped by recent(Cenozoic RANGELANDS14(2), April 1992 109

Murphy, D.R.1989a. Drainage.pp.6-8. In: K.L.Johnson (ed.).1989. Stokes,W.L. 1986. . Utah Mus. ofNat. Hist. Occas. RangelandResources of Utah. Utah RangelandComm. (uneum. Pap. No.6. Utah Mus.Nat. Hist. andUtah Geol. and Mm. Surv., Salt pub.). Utah StateUniv. Coop.Ext. Ser. coop. with UtahDept. Agr. Lake City, Utah. 280 p. and Utah Div. WildI. Res., Logan, Utah. 103. p. Murphy, D.R. 1989b. Physical features of Utah. pp. 4-6. In: K.L. Johnson (ed.). 1989. RangelandResources of Utah. Utah Range- land Comm. (unenum. pub.). Utah State Univ. Coop. Ext. Ser. coop. with Utah Dept.Agr. and UtahDiv. Wildl. Res., Logan, Utah. 103 p.

Vegetation Types of Utah

Roger E. Banner

Utah is aland of contrast.Elevations range from2,350 ft in extreme southwesternUtah to 13,528 ft at King's Peak in the Uinta Mountainsin northeastern Utah (MacMahon 1988). The wide variety of physical features that occur, linked to the diversity of plant and animal communities, produces many kinds ofrangeland ecosystems. Although many vegetation maps have been produced over the years, KUchier (1964, 1970) compiledmaps showing the potential natural vegetationof the conterminous with 20 subdivisionsshown for Utah. One ofthese, , occurs primarilyon old lake bottomsthat are now salt flat and is essentially devoid of vegetation. Küchler's map subdivisionsfor Utah give adequate detail and are recognizable, makingthem appropriatevegetation units for discussion in an overview (MacMahon 1988, West 1989). This paper summarizes information presented by West (1989). Alpine Zone Alpine ecosystems in Utahoccur in mountainousareas above timberline, usuallyabove 11,000 ft. The 498,000ac classified as alpine meadows and barrens and (Yorks SubalpineZone vegetation on the Aquarius Plateauof southcen- McMullen1980b) in Utah is located in the Uinta Moun- tral Utah. tains. Small alpine areas occur on other Utah mountain Domestic sheep grazing has been the primary human ranges. use of the alpine zone in Utahsince the mid-nineteenth Vegetationof this zone is called tundra and is domi- century.However, it has steadily declinedover thepast 40 nated by mosses and lichens, low-growing, perennial Much of the zone is low in herbaceous and vascular Tree years. alpine inherently pro- prostrate shrubby plants. ductivity yet relatively high in ecological condition. species present grow along the ground and appear as shrubs. Usually,fewer than 200 alpine plant species are SubalpineZone present on any given mountain range. Grasses and The subalpinezone runs down slope from the alpine sedges are widespread and species of the mustard, rose, zone to approximately9,000 ft. The subalpine zone in saxifrage, buckwheat, and pink families are common. Utah is estimated to be 1,250,000ac. The largest areas of the Tufted hair grass, alpine avens, and sedge are prevalent this zone occur in the Uinta Mountains and cap on many dry and wet meadow sites. Watersedge is com- Wasatch, Paunsagunt, Markagunt, Aquarius, and Tava- mon in bog communities, and shrub thickets are often puts Plateaus. Small areas occur on otherUtah mountain dominated by willows; Drummond willow, grayleaf wil- ranges. low, or plain-leafwillow. Undisturbed forested sites within the subalpine zone are dominated by conifers such as Engelmann and blue The author is Assistant Professorand ExtensionSpecialist, Range Science spruce, and subalpineand white (true) firs. Intermingled Department,Utah State University, Logan, Utah 84322-5230.