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Home , Fort Utah, Geology of Utah, Humbug Formation, Provo Peak, Wasatch Front, Wasatch Range

Figure 2. Looking down Rock Canyon to the west toward Lake. The prominent folded rocks shown here are Humbug Formation, Deseret ,Rock and Canyon Gardison Formation. near Photo is courtesyProvo, of Beau Walker.Utah County: A Geologic Field Laboratory

Bart J. Kowallis and Laura C. Wald Department of Geological Sciences, University Provo, Utah 84604 [email protected]

Utah Geosites 2019 Utah Geological Association Publication 48

M. Milligan, R.F. Biek, P. Inkenbrandt, and P. Nielsen, editors

Figure 3. Headline and part of the article from the Provo Daily Her- ald, 29 July 1936, p. 1, reporting on the flood out of Rock Canyon Figure 4. Flood waters flowing out of Rock Canyon along Temple the previous day. Rain had begun in the mountains in the early af- View Drive in Provo in early June 1983. Photo by Bart Kowallis. ternoon. Lewis Richards, who was at his homesteadCover Image: inLooking the canyon down Rock Canyon to the west toward . heard the roaring of the flood at about 2 p.m. and reported that, “It looked like the whole mountain had begun to move.” Flooding also occurred from similar storms in other central Utah communities the same day. 2 M. Milligan, R.F. Biek, P. Inkenbrandt, and P. Nielsen, editors 2019 Utah Geological Association Publication 48

Presidents Message I have had the pleasure of working with many diff erent geologists from all around the world. As I have traveled around Utah for work and pleasure, many times I have observed vehicles parked alongside the road with many people climbing around an outcrop or walking up a trail in a canyon. Whether these people are from Utah or from another state or country, they all are quick to mention to me how wonderful our geology is here in Utah. Utah Geosites 2019 Utah is at the junction of several diff erent geological provinces. We have the Basin and Range to the west and the Central Utah Utah Geological Association Publication 48 Hingeline and Th rust Belt down the middle. Th e M. Milligan, R.F. Biek, P. Inkenbrandt, and P. Nielsen, editors have outcrops of some of the oldest sedimentary rock in Utah. Utah also has its share of young cinder cones and basaltic lava Utah Geosites showcases some of Utah’s spectacular geology, both fl ows, and ancient , stratovolcanoes, and plutonic rocks. little-known localities and sites seen by visitors to Utah’s many Th e general public comes to Utah to experience our wonderful national and state parks and monuments. Th e geosites refl ect the scenic geology throughout our state and national parks. Driving interests of the many volunteers who wrote to share some of their between our national and state parks is a breathtaking experience. favorite geologic sites. Th e list is eclectic and far from complete, and we hope that additional geosites will be added in the coming Th e “Utah Geosites” has been a great undertaking by many people. years. Th e also maintains a list of geosites I wanted to involve as many people as we could in preparing this https://geology.utah.gov/apps/geosights/index.htm. guidebook. We have had great response from authors that visit or work here in the state. Several authors have more than one site that We thank the many authors for their geosite contributions, they consider unique and want to share with the rest of us. I wanted Utah Geological Association members who make annual UGA to make the guidebook usable by geologists wanting to see outcrops publications possible, and the American Association of Petroleum and to the informed general public. Th e articles are well written Geologists—Rocky Mountain Section Foundation for a generous and the editorial work on this guidebook has been top quality. grant for desktop publishing of these geosite papers. I would like to personally thank Mark Milligan, Bob Biek, and Design and desktop publishing by Jenny Erickson, Graphic Paul Inkenbrandt for their editorial work on this guidebook. Designer, dutchiedesign.com, Salt Lake , Utah. Th is guidebook could not have happened without their support. I would like to thank Jenny Erickson for doing the great desktop Th is is an open-access article in which the Utah Geological publishing and the many authors and reviewers that helped Association permits unrestricted use, distribution, and reproduction prepare the articles. Your work has been outstanding and will of text and fi gures that are not noted as copyrighted, provided the certainly showcase the many great places and . original author and source are credited. See the Utah Geological Last, but not least, Th ank you to the American Association of Association website, www.utahgeology.org, and Creative Commons Petroleum Geologists, Rocky Mountain Section Foundation for https://creativecommons.org/licenses/by/4.0/ for details. their fi nancial support for this publication.

Suggested citation for this geosite: Guidebook 48 will hopefully be a dynamic document with the potential to add additional “geosites” in the future. I hope more Kowallis, B.J., and Wald, L.C., 2019, Rock Canyon near Provo, authors will volunteer articles on their favorite sites. I would like Utah County—a geologic fi eld laboratory, in Milligan, M., to fi ll the map with locations so that a person or family looking at Biek, R.F., Inkenbrandt, P., and Nielsen, P., editors, Utah the map or articles will see a great location to read about and visit. Geosites: Utah Geological Association Publication 48, 15 p., Enjoy Guidebook 48 and enjoy the geology of Utah. https://doi.org/10.31711/geosites.v1i1.58. Peter J. Nielsen 2019 UGA President

2 B.J. Kowallis and L.C. Wald Rock Canyon

INTRODUCTION maintained by the city of Provo. Th e amphitheater is available to the public for special programs or outdoor classroom use. Th e re- Rock Canyon near Provo, Utah is an ideal outdoor laboratory. Th e mainder of the canyon lies within the Uintah National Forest and is canyon has been known and explored for many years by scientists under the jurisdiction of the Pleasant Grove Ranger District. If you and students for its fascinating geology, biology, and botany. It is have any questions about the pavilion and park area please contact also a favorite location for rock climbers, hikers, and other out- the Provo City Parks and Recreation Department. For questions door enthusiasts. Facilities near the mouth of the canyon including regarding the canyon please contact the National Forest Service. parking, restrooms, a lecture amphitheater, and a covered pavilion with picnic tables provide an ideal location for visitors (fi gure 1). Although the canyon is beautiful, it also contains some hazards that visitors should be aware of. Among the plants that thrive in Geology is the focal point of this beautiful canyon with a history the lower reaches of the canyon is poison ivy, a plant that causes a that stretches from the (about 700 million years ago) severe, blistering rash in most people. Hikers should learn to rec- to the and , which covered much of ognize this plant before exploring the canyon. Th e canyon is also western Utah at its peak roughly 18,000 years ago (fi gure 2). Ex- home to rattlesnakes. Th ese snakes will generally try to avoid hu- cellent exposures of the rocks allow visitors to see features clearly mans, but if disturbed or cornered, they will strike and their bite is and piece together the history of the canyon. Th e oldest rocks are painful and dangerous. If bitten, you should seek immediate med- glacial deposits of the Mineral Fork Tillite. Th e tillite is overlain by a thick section of rocks of to age, all of which have been deformed into an asymmetric, overturned fold formed during the , a roughly 140 to 50 million year old mountain building event. Th e upper reaches of the can- yon were sculpted by glaciers during the and deposits of the Provo and Bonneville levels of Lake Bonneville are found at the mouth of the canyon, now cut by a recent alluvial fan. Also, at the mouth of the canyon are excellent exposures of features associ- ated with the Wasatch fault.

Visitors are asked to please respect the canyon’s natural beauty and minimize human impact by adhering to regulations and by on designated paths. Please be careful not to litter; remem-Figure 2. Looking down Rock Canyon to the west toward Utah Lake. The prominent folded rocks shown here are Mississippian Humbug Formation, DeseretFigure Limestone, 2. Looking and Gardison down Formation.Rock Canyon Photo is to courtesy the west of Beau toward Walker. Utah Lake. Th e prominent ber, what you take in, you must also take out. Th e mouth of Rock folded rocks shown here are Mississippian Humbug Formation, Deseret Limestone, Canyon, including the pavilion, restrooms, and parking lot is and Gardison Formation. Photo is courtesy of Beau Walker.

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o le Drive a mp d Te Provo Rock 2230 North h r t Temple State Street No Canyon Parking Area & Restrooms C Figure 3. Headline and part of the article from the Provo Daily Her- o Figure 4. Flood waters flowing out of Rock Canyon along Temple University Avenue University ald, 29 July 1936, p. 1, reporting on the flood out of Rock Canyon lu m View Drive in Provo in early June 1983. Photo by Bart Kowallis. b the previous day. Rain had begun in the mountains in the early af- ia Lavell ternoon. Lewis Richards, who was at his homestead in the canyon Map Key L Edwards heard the roaring of the flood at about 2 p.m. and reported that, “It Y a N Major roads n Stadium looked like the whole mountain had begun to move.” Flooding also Mountain e occurred from similar storms in other central Utah communities the Streets same day. Hiking trails

900 East 900 2 Parks 0 Scale miles 0.5 Brigham Bulldog Blvd Young University Y Figure 1. Index map showing the location of Rock Canyon and the major roads providing access to the canyon. Th e star shows the location of the parking area, rest rooms, and pavilion at the mouth the of the canyon. Figure 1. Index map showing the location of Rock Canyon and the major3 roads providing access to the canyon. The star shows the location of the parking area, rest rooms, and pavilion at the mouth of the canyon.

1 M. Milligan, R.F. Biek, P. Inkenbrandt, and P. Nielsen, editors 2019 Utah Geological Association Publication 48

ical attention. Finally, the canyon has many great places for rock Starting in about 1925, citizen groups in the valley began to try climbing, but loose rock and improper gear or training can and has and address the flooding problems, and with the help of the fed- resulted in disaster. One or more serious accidents or deaths occurs eral government, some progress was made, including the terrac- each year in the canyon due to falls from rocky slopes or cliffs. ing of the high, steep, rocky slopes of the canyon by the Civilian Conservation Corps (CCC) during 1933 and 1934 (Bush, 1995). EARLY CANYON EXPLORATION FigureBut 2.despite Looking downthese Rock efforts, Canyon to overgrazingthe west toward Utah in theLake. canyonThe prominent continued folded rocks shownand here are Mississippian Humbug Formation, Deseret Limestone, and Gardison Formation. Photo is courtesy of Beau Walker. J. Marinus Jensen (1924) self-published a book entitled the Early it was not until after the flooding in three consecutive years in the History of Provo, Utah. Jensen reports that the first mention of 1950’s that the overgrazing problem was addressed (Bush, 1995). Rock Canyon in local history is related to the difficult time the Figure 3. Headline and part early settlers of (later named Provo) had with the Ute of the article from the Provo Indians. The Utes were understandably disturbed by the pioneers , 29 July 1936, p. 1, reporting on the flood out taking over their valley. The disputes peaked in 1850 when a of Rock Canyon the previous battle broke out along the between approximately 70 day. Rain had begun in Indians, led by Big Elk, and a militia of Mormon men. For several the mountains in the early afternoon. Lewis Richards, days the battle continued until one evening the Indians, many who was at his homestead in of whom were wounded, took flight. In their escape they split the canyon heard the roaring of the flood at about 2 p.m. into two groups; one headed south toward , and the and reported that, “It looked other smaller group went toward Rock Canyon. Big Elk headed like the whole mountain had the Rock Canyon group; however, he was severely wounded and begun to move.” Flooding also occurred from similar died near the mouth of the canyon. As the militia approached storms in other central Utah communities the same day. Rock Canyon in pursuit of the Indians, it is rumored that Big Elk’s Figure 3. Headline and part of the article from the Provo Daily Her- ald, 29 July 1936, p. 1, reporting on the flood out of Rock Canyon Figure 4. Flood waters flowing out of Rock Canyon along Temple squaw attempted to climb the cliffs, but fell and was killed. Squaw the previous day. Rain had begun in the mountains in the early af- View Drive in Provo in early June 1983. Photo by Bart Kowallis. Figure 2. LookingPeak, downnear the Rock mouth Canyon of the canyon,to the west was supposedlytoward Utah named Lake. for The prominentternoon.The Lewismost Richards,folded recent who rocksserious was at shownhis flooding homestead here in problemsthe are canyon Mississippian occurred in Humbug1983 after heard the roaring of the flood at about 2 p.m. and reported that, “It Formation, Deseretthe incident. Limestone, Frequent and travel Gardison into Rock Formation. Canyon beganPhoto after is courtesy July of oflookeda Beauseries like the Walker.of whole wetter mountain than had normal begun to move.” months Flooding beginning also in September of occurredthe previous from similar year. storms Thein other centralwet cool Utah communitiesweather thepersisted until late May 1855 when “William M. Wall was given a grant to build a road. On same day. completion of the road he was to be permitted to charge fifty cents and early June of 1983 when the temperatures2 warmed and flood- for each load of wood hauled out of the canyon. There was also a ing began. A Provo Daily Herald headline on the front page of the provision in the order to the effect that the grantee should allow May 30th edition that year read “Crews Sandbag Temple View,” as all persons desiring to do so, to work on the road; and that they the road out of Rock Canyon was temporarily turned into a river should receive, as compensation therefore, the right to haul out (figure 4). After the 1983 floods, the catchment basin at the mouth eight loads of wood for every day’s work performed.” No mention of the canyon was enlarged to guard against further problems. This was made of any fee for geology excursions, rock collecting, or rock basin now serves as a city park when not needed for flood control. climbing; evidently they were not “popular” activities back then.

Due to the need for water and timber, the early settlers of exploited these resources and depleted them (Bush, 1995). During the 1860’s, Rock Canyon was settled by a few pioneer families and Rock Canyon Creek also provided the early settlers in Provo with drinking water (Jensen, 1924). Some land was cleared in the canyon to use for farming including fruit orchards (Bush, 1995). However, the land proved to be too hostile for the Euro- pean farming methods, and was quickly abandoned. The canyon proved to be more amenable to raising cattle and sheep. Livestock were taken up the canyon to graze during the summer and this quickly became so popular that overgrazing stripped the land of most of its vegetation (Jensen, 1924; Wilson, 1988). This in turn led to flooding where debris and water from the canyon flowed out into the valley often causing damage to farms and structures Figure 3. Headline and part of the article from the Provo Daily Her- built in or near the mouth of the canyon. Flood incidents occurred ald, 29 July 1936, p. 1, reporting on the flood out of Rock Canyon FigureFigure 4. Flood 4. Flood waters waters flowing flowing out of outRock ofCanyon Rock along Canyon Temple Viewalong Drive Temple in Provo quite frequently between 1896 and 1984 (Bush, 1995). One of the in early June 1983. Photo by Bart Kowallis. the previous day. Rain had begun in the mountains in the early af- View Drive in Provo in early June 1983. Photo by Bart Kowallis. ternoon. Lewismost Richards, disastrous who floods was atoccurred his homestead on 28 July in 1936 the (figurecanyon 3). 4 heard the roaring of the flood at about 2 p.m. and reported that, “It looked like the whole mountain had begun to move.” Flooding also occurred from similar storms in other central Utah communities the same day. 2 B.J. Kowallis and L.C. Wald Rock Canyon

AGE ROCKFORMATIONS CANYON,THICKNESS PROVO - ft. UTAHNOTES AGE 0-10,000 yrs old millions Alluvium, colluvium, soil 0-50

Q 10,000-30,000 yrs old years Lake Bonneville deposits 0-200 Gulf Oil-Banks #1 1 Buried valley fill in 23-8S-2E Utah Valley includes 13,000 ft deep, bottomed pre-Bonneville alluvial in beds containing 10 & lake deposits with 0-13,000 Late pollen some interbeds of 10 m.y. + volcanic see Cook et al., 1997 for

MIO-PLIO ( 15 Bouguer gravity map) WASATCH FAULT ZONE SEPARATES UTAH VALLEY FILL FROM PALEOZOIC BEDROCK OF WASATCH MOUNTAINS SHOWN BELOW 285 1000’ sandstone 1200’ Curry Peak siltstone facies Pseudoschwagerina mostly fine sandstn with some 290 siltstone interbeds Granger Mountain Formation 8200- Schwagerina PERMIAN (Wolfcampian) 10,200

295 fine grained sandstone with heavy minerals from Uncompahgre source

1400’ Curry Peak siltstone 300 facies

Wallsburg Ridge Triticites Formation 4000- mostly fine grained sandstone (Missourian-Virgilian) 7000 with fewer limestone interbeds than same interval in 305 Eowaeringella Shingle Mill Ls 300 equivalent to Jordan & (Lower Missourian) Commercial Lst at Bingham Oquirrh Group

Fusulina Bear Canyon 310 Formation 3250 (Atokan-Desmoinesian) Profusulinella

Morrowan are Bridal Veil abundant - 315 Limestone 1245 corals, bryozoans Dictyoclostus Cravenoceras 320 Manning Canyon Shale 1650 Lepidodendron

deep water facies Upper limestone 325 Great member 1800 Blue Ls Long Trail Sh Mbr 300 forms strike valley 330 Topliff Ls Mbr 700 Apatognathus Fenestella 335 Humbug Formation 540 Taphrognathus 345 Deseret Limestone 840 Spathognathodus MISSISSIPPIAN 350 Gardison Limestone 550 Syringopora, Gnathodus 6 feet of Pinyon Pk Fm at base

360 D Fitchville Dolomite 260 REGIONAL UNCONFORMITY 505 Maxfield Limestone 600 white dolostone in Rock Canyon 510 Ophir Formation 0-250 Glossopleura orange, highly fractured in Rock Canyon 515 CAMB Tintic 1100

olive-drab, phyllitic diamictite 700 Mineral Fork Tillite 145 purple & tan argillite in Slate Cny 775 Big Cottonwood Formation 1350+ only in subsurface in Rock Cny PROT

Figure 5. Stratigraphic column for the Rock Canyon area modifi ed from Hintze and Kowallis Figure(2009). Th 5. e BigStratigraphic Cottonwood Formation column shown for on thethe columnRock is Canyonnot exposed areain the modifiedcanyon, but it fromis just a Hintze couple miles and south Kowallis in Slate Canyon. (2009). Also, theThe Mio- Big Cottonwood sediments are onlyFormation in the sub- shownsurface of onthe valleythe columndeposits. Th isis thicknot pileexposed of sediments in inthe the canyon,valley are evidence but it of isthe justamount a of uplift and erosion that has occurred along the Wasatch fault zone over the last 10-12 million coupleyears. In themiles column south of notes in are Slatelisted a fewCanyon. of the fossils Also, (in italics) the thatMio-Pliocene occur in these rocks. sedi- ments are only in the subsurface of the valley deposits. This thick pile of sediments in the valley are5 evidence of the amount of uplift and erosion that has occurred along the Wasatch fault zone over the last 10-12 million years. In the column of notes are listed a few of the fossils (in italics) that occur in these rocks.

3 M. Milligan, R.F. Biek, P. Inkenbrandt, and P. Nielsen, editors 2019 Utah Geological Association Publication 48

N

Scale miles N

0 0.1 0.2 0.3 0.4 0.5 Scale miles

0 0.1 0.2 0.3 0.4 0.5 pCmf Ct Co Cm DMf Mg Md Mh Mgb TQaf Qlb Qa Qls Mineral Tintic Ophir Maxfield Fitchville Gardison DeseretpCmfHumbug Ct Great Co Pre- Cm Lake DMfStream (Qal)MgLandslideMd Mh Mgb TQaf Qlb Qa Qls Fork Quartzite Formation Limestone Dolomite Limeston Limestone Formation Blue Bonneville Bonneville Fan (Qaf) deposits Tillite Mineral TinticLimestoneOphirdepositsMaxfielddepositsFitchvilleColluviumGardison Deseret Humbug Great Pre- Lake Stream (Qal) Landslide Fork Quartzite Formation Limestone Dolomite(Qac) depositsLimeston Limestone Formation Blue Bonneville Bonneville Fan (Qaf) deposits Tillite Limestone deposits deposits Colluvium FigureFigure 6. Geologic Geologic map mapof the ofRock the Canyon Rock area Canyon showing area the location showing of the the BYU location campus in of relation the BYU to Rock campus Canyon reproducedin relation from to Hintze Rock (1978). Canyon Th e reproducedcurrent parking from lot, (Qac) deposits rest room, and pavilion are located approximately where the words “Rock Canyon” are on the map. Hintze (1978). The current parking lot, rest rooms, and pavilion are locatedFigure approximately 6. Geologic wheremap of the the words Rock “RockCanyon Canyon” area showing are on the locationmap. of the BYU campus in relation to Rock Canyon reproduced from GEOLOGIC HISTORY OF ROCK CANYON OjakangasHintze (1978). and TheMatsch current (1980) parking and Matschlot, rest androoms, Ojakangas and pavilion (1991) are located approximately where the words “Rock Canyon” are on the map. proposed that the lower part of the formation was deposited in a Th e rocks exposed in Rock Canyon range in age from Neoprotero- terrestrial glacial environment, while the upper part was deposited zoic to Recent (fi gures 5 and 6; Baker, 1972; Hintze, 1978; Davis, in a marginal-marine glacial environment (fi gure 8), and that the 1983). Th e oldest rocks are exposed near the mouth of the canyon entire sequence was deposited by glaciers in a more temperate en- while the youngest bedrock units are found on the high peaks W E vironment rather than a polar environment. Christie-Blick (1982) (Cascade Mountain, , and ) at the head of ? W E questioned the idea of a terrestrial glacial environment, insteadIce the canyon. preferringSTAGE a submarine, grounded-ice environment. ? Ice Sea 2 Land STAGE Rocks (Precambrian) Sea 2 Land Th e oldest rocks found in Rock Canyon are diamictites of the Mineral Fork Tillite that are well exposed on the north canyon wall near the water storage tank (fi gure 6). Th e outcrops are com- posed of cobbles and pebbles of quartzite, dolomite, and limestone Ice (with rare clasts of other rock types) surrounded by a fi ne-grained ? Ice matrix (Baker 1973), which has been weakly metamorphosed STAGE Sea Land ? producing a secondary foliation and phyllitic character in the 1 STAGE Sea Land matrix (fi gure 7). Over the years, there has been some debate as 1 to the origin of these deposits, but the general consensus current- Figure 8. Two-stage model for deposition of the Mineral Fork Til- Figurely is that 7. Close-up they were view deposited of Mineral by ancient Fork Tillite glaciers showing (Varney, small 1976; peb - lite proposed by Matsch and Ojakangas (1991). Stage 1 was a de- Figure 8. Two-stage model for deposition of the Mineral Fork Til- blesOjakangas of quartzite and Matsch,and dolomite 1980; floatingChristie-Blick, in a fine-grained 1983; Crittenden matrix that Figureposition 7. 7.Close-up inClose-up a terrestrial view ofview Mineral glacialof MineralFork Tillitesetting Fork showing while Tillite small stage showing pebbles 2 was of quartzitesmall a marginal peb and- lite proposed by Matsch and Ojakangas (1991). Stage 1 was a de- hasand been others, metamorphosed 1983; Link and producing others, 1994; a secondary Christie-Blick, foliation 1997). that in dolomiteblesmarine of flquartzite glacialoating in setting.aand fi ne-grained dolomite Arrows matrix floating indicate that has in been inputa fine-grainedmetamorphosed of sediment producing matrix into that the position in a terrestrial glacial setting while stage 2 was a marginal places becomes a crenulation cleavage. foliationhasdeposits. been that metamorphosed in places becomes a crenulationproducing cleavage. a secondary foliation that in marine glacial setting. Arrows indicate input of sediment into the 6 places becomes a crenulation cleavage. deposits. 4 4 N

Scale milesN 0 0.1 0.2 0.3 0.4 0.5 Scale miles

0 0.1 0.2 0.3 0.4 0.5 pCmf Ct Co Cm DMf Mg Md Mh Mgb TQaf Qlb Qa Qls Mineral Tintic Ophir Maxfield Fitchville Gardison Deseret Humbug Great Pre- Lake Stream (Qal) Landslide pCmfFork QuartziteCt FormationCo LimestoneCm DolomiteDMf LimestonMg LimestoneMd FormationMh MgbBlue BonnevilleTQaf BonnevilleQlb FanQa (Qaf) depositsQls Tillite Limestone deposits deposits Colluvium Mineral Tintic Ophir Maxfield Fitchville Gardison Deseret Humbug Great Pre- Lake (Qac)Stream deposits (Qal) Landslide Fork Quartzite Formation Limestone Dolomite Limeston Limestone Formation Blue Bonneville Bonneville Fan (Qaf) deposits FigureTillite 6. Geologic map of the Rock Canyon area showing the location of the BYU campusLimestone in relationdeposits to Rockdeposits CanyonColluvium reproduced from (Qac) deposits West East Hintze (1978). The current parking lot, rest rooms, and pavilion are located approximately where the words “Rock Canyon” are on the map. Outer Shelf Carbonate platform Figure 6. Geologic map of the Rock Canyon area showing the location of the BYU campus in relation to Rock Canyon reproduced from Hintze (1978). The current parking lot, rest rooms, and pavilion are located approximately where the words “Rock Canyon” are on the map. Sea level Sand Limestone Dolomite Shale

Shale West Older Rocks East Outer Shelf Carbonate platform Lagoon B.J. KowallisW and L.C. Wald E Rock Canyon Sea level Figure 12. Cambrian depositional system (modified from Sand Hintze ? Ice West Limestone East W E and Kowallis, 2009). Dolomite Outer Shelf Carbonate platform LagoonShale STAGE Sea ? Ice Shale 2 Land Sea level Older Rocks Sand Limestone STAGE Dolomite Sea Shale 2 Land Figure 9. Small pebbles of dark quartzite and white vein quartz FigureShale 12. Cambrian depositionalFitchville Dolo. system (modified from Hintze within the Tintic Quartzite. Weathered (orange-tan, lower right) and and Kowallis, 2009). Older Rocks unweathered (light gray) surfaces of this unit are shown. Pinyon Peak Fm. Ice Figure 12. Cambrian depositional system (modified from Hintze ? and Kowallis, 2009). ? Ice STAGE Sea Land Maxfield Lst. Figure 9. Small pebbles of dark quartzite and white vein quartz Fitchville Dolo. 1 ? within the Tintic Quartzite. Weathered (orange-tan, lower right) and STAGE Sea Land unweathered (light gray) surfaces of this unit are shown. Pinyon Peak Fm. 1 m Figure1 8. Two-stage model for deposition of the Mineral Fork Tillite proposed by Figure 9. Small pebbles of dark quartzite and white vein quartz withing the Tintic 1 m Figure 8. Two-stage model for deposition of the Mineral Fork Til- Figure 9. Small pebbles of dark quartzite and white vein quartz Fitchville Dolo. Matsch and Ojakangas (1991). Stage 1 was a deposition in a terrestrial glacial setting withinQuartzite. the Weathered Tintic Quartzite. (orange-tan, Weatheredlower right) and (orange-tan, unweathered lower(light gray) right) surfaces and ? Figure 7. Close-up view of Mineral Fork Tillite showing small peb- litewhile proposed stage 2 was by a marginal Matsch marine and glacialOjakangas setting. Arrows(1991). indicate Stage input 1 was of sediment a de- of this unit are shown. unweathered (light gray) surfaces of this unit are shown. MaxfieldPinyon Lst. Peak Fm. bles of quartzite and dolomite floating in a fine-grained matrix that positionFigureinto the 8.deposits. in Two-stage a terrestrial model glacial for setting deposition while of stage the Mineral2 was a marginalFork Til- Pinyon Peak Fm. hasFigure been 7. Close-upmetamorphosed view of producing Mineral Fork a secondary Tillite showing foliation small that peb in- marinelite proposed glacial by setting. Matsch Arrows and Ojakangas indicate input(1991). of Stagesediment 1 was into a thede- placesbles of becomes quartzite a and crenulation dolomite cleavage. floating in a fine-grained matrix that deposits.position in a terrestrialCambrian glacial to setting while Rocks stage 2 was a marginal Figure 13. Contact between? the Cambrian Maxfield Limestone and has been metamorphosed producing a secondary foliation that in marine glacial setting. Arrows indicate input of sediment into the Devonian1 mFitchvilleMaxfield Dolomite Lst. in Rock Canyon with a few feet of Th e Cambrian was a time of shallow seas and shorelines in what places becomes a crenulation cleavage. 4 deposits. Pinyon Peak Formation between them (modified from Clark and is now Utah. Th e oldest Cambrian rock unit in the canyon is the others, 2014). 4 Tintic Quartzite. It is an orange- to tan-weathering quartzite that 1 m is light greenish gray on unweathered surfaces. Th e sandstone Figure 13. Contact between the Cambrian Maxfield Limestone and from which the quartzite originated was composed of fairly clean, Figure 10. Rusty-colored Skolithos burrows in the Tintic Quartzite. Devonian Fitchville Dolomite in Rock Canyon with a few feet of rounded to subrounded quartz grains of fi ne- to medium-grain Pinyon Peak Formation between them (modified from Clark and size with local coarse-grained interbeds (Baker and others, 1949; others,Figure 13.2014). Contact between the Cambrian Maxfield Limestone and Lochman-Balk, 1976). Cross-bed sets up to 3 to 4 feet (1 m) thick Devonian Fitchville Dolomite in Rock Canyon with a few feet of can be observed in this rock unit. Some layers contain abundant Pinyon Peak Formation between them (modified from Clark and well-rounded pebbles of quartzite or vein quartz (fi gure 9) and at others, 2014). Figure 10. Rusty-colored Skolithos burrow in the Tintic Quartzite. several localities, trace burrows (called Skolithos) occur in Figure 10. Rusty-colored Skolithos burrows in the Tintic Quartzite. the outcrops (fi gure 10; see also Peterson and Clark, 1974).

Figure 10. Rusty-colored Skolithos burrows in the Tintic Quartzite. Th e Tintic Quartzite unit outcrops as highly-fractured, rough ledges and cliff s in the lower part of the canyon (fi gure 11). At the mouth of the canyon, the Tintic Quartzite is gently dipping, but a short distance into the canyon the unit is vertical to slightly over- turned. It is in some of these vertical quartzite beds where has become quite popular.

Toward the top of the Tintic Quartzite the unit interfi ngers with the overlying Ophir Shale (Baker, 1972, 1973). Like the Tintic Quartzite, the Ophir Shale has been slightly metamorphosed and would be more properly classifi ed as a phyllite rather than a shale. Poorly preserved FigureFigure 11. 11. Squaw Squaw Peak asPeak seen fromas seenNorth Templefrom Drive.North Th Temple e orangish Drive. tan, gently The orangishdipping Tintic tan, Quartzite gently is distinctivedipping atTintic the base Quartzite of the peak isand distinctive overlain by grayat the fragments and pieces of may be found in the Ophir Shale. Paleozoic dolomite and limestone beds. base of the peak and overlain by gray Paleozoic dolomites and . Th e fi nal Cambrian unit exposed in Rock Canyon is the Maxfi eld Th e Cambrian depositional system is represented in fi gure 12 with Limestone (fi gures 5 and 6). Th e lower two-thirds of this forma- shoreline sands eastward of a broad subtidal carbonate platform 5 tion consists of a mottled dark- to medium-gray limestone, while Figureand deeper 11. Squawwater slope Peak deposits as seen to from the west North (Hintze Temple and Drive. Kowallis, The the upper third is a medium- to very light-gray banded dolomite orangish2009). In tan,the Rockgently Canyon dipping area, Tintic the TinticQuartzite Quartzite is distinctive was depos- at the base of the peak and overlain by gray Paleozoic dolomites and (Granger and other, 1952; Hintze, 1978) Fossils are sparse in the ited as shoreline and near shore sands. Th en as sea level rose, the limestones. Maxfi eld Limestone, but some , gastropod, and bryozoan Figureshoreline 11. moved Squaw farther Peak east.as seen First from the lagoonal North Temple muds of Drive. the Ophir The orangish tan, gently dipping Tintic Quartzite is distinctive at the fragments have been found, as well as conodont microfossils (Hin- Shale and then the carbonates of the Maxfi eld Limestone were 5 base of the peak and overlain by gray Paleozoic dolomites and deposited atop the sand due to a major pulse of sea level rise. tze, 1978; Clark and others, 2014). limestones. 7 5 M. Milligan, R.F. Biek, P. Inkenbrandt, and P. Nielsen, editors 2019 Utah Geological Association Publication 48

West East Mississippian, Pennsylvanian, and Permian Rocks Outer Shelf Carbonate platform Lagoon Sea level Th e Rock Canyon area remained at or near sea level for the next Sand Limestone 100 million years, throughout the Mississippian, Pennsylvanian, Dolomite Shale and Permian Periods. However, in the Mississippian, an area of Shale increased subsidence developed on the continental shelf margin in Older Rocks the area of northwestern and north-central Utah, which persist- ed through the Permian. Th is basin, where thousands of feet of Figure 12. 12. Cambrian Cambrian depositional depositional system (modifi system ed from (modified Hintze and Kowallis, from 2009). Hintze sediment accumulated, is called the Oquirrh Basin (Jordan and and Kowallis, 2009). Following Cambrian time, a major period of erosion and Douglass, 1980: Erskine, 1997) and was part of a series of basins non-deposition occurred in the Rock Canyon area due to a drop and uplift s that formed the Ancestral (fi gure 14; in sea level. Th is unconformity disappears to the west where depo- Lee, 1918; Ver Wiebe, 1930; Kluth, 1986; Ye and others, 1996). In sition was still occurring. Beginning about 20 to 25 miles (30-40 the Rock Canyon area, deposits into the Oquirrh Basin during this Figure 9. Small pebbles of dark quartzite and white vein quartz km) west of Rock Canyon,Fitchville Cambrian-age Dolo. strata become thicker. within the Tintic Quartzite. Weathered (orange-tan, lower right) and time period totaled over 20,000 feet (6000 m) or approximately In addition, rocks, which are absent in Rock Canyon, unweathered (light gray) surfaces of this unit are shown. Pinyon Peak Fm. four miles (6.5 km) of strata (Baker, 1972; Hintze, 1978). Th ese appear and also thicken to the west. Th e area between these thick- rocks (including the Gardison Limestone, Deseret Limestone, er deposits off to the west? and the thinner deposits to the east is Humbug Formation, Great Blue Limestone, Manning Canyon called the “hingeMaxfield line” orLst. “Wasatch line” and marks the transition Shale, and Oquirrh Group) make up the bulk of the bedrock lo- from the stable shallow continental shelf margin to a more rapidly cated from about one mile (1.6 km) into the canyon to the tops of subsiding part of the continental margin called a miogeosyncline the highest peaks surrounding the canyon (fi gure 15). Limestones (Kay, 1951;1 m Bissell, 1974, Stokes, 1976). and sandstones of the Humbug Formation form the capping rocks atop Squaw Peak, while the Manning Canyon Shale forms the Although rocks of Ordovician and age are not currently valley and slopes below cliff s of the Oquirrh Group through which found in Rock Canyon, thin deposits of rocks of these ages likely the Squaw Peak/Rock Canyon picnic area road winds. As you hike Figureonce existed 13. Contact in this betweenarea, but theduring Cambrian the early Maxfield part of the Limestone Devonian and through the canyon, you may fi nd some marine fossils (corals, DevonianPeriod they Fitchville were eroded Dolomite away. Laterin Rock in the Canyon Devonian, with thea few ocean feet of snails, bivalves, etc.) within these rock formations as well as darker Pinyonagain covered Peak Formationthe area and between sediments them were (modified deposited from atop theClark and and harder lumps of . Limestones will fi zz with the applica- others,erosional 2014). surface. Th ese Devonian-age sediments are relatively thin, accumulatingWest only to a thickness of about 250 feet (75 m) in theEast Outer Shelf Carbonate platform Lagoon WYOMING Rock Canyon area (fi gures 5 and 6) and are called the Fitchville Do- Sea level Oquirrh Basin lomite or Fitchville Formation (Baker, 1972; Hintze, 1978; HintzeSand Figure 10. Rusty-colored Skolithos burrows in the Tintic Quartzite. Limestone Dolomite and Kowallis, 2009). Th e Fitchville Dolomite consistsShale of about 20

feet (6 Shalem) of dolomitic sandstone at the base overlain by relatively Front Range Uplift Rock unfossiliferous light- to medium-gray, vuggy dolomiteOlder Rocks(Hintze, COLORADO Canyon 1978). Clark and others (2014) found that the lowermost few feet of Eagle -- Central -- Taos Basin theFigure Fitchville 12. Cambrian Formation depositional in Rock Canyon system contain (modified fossil conodonts from Hintze (microscopicand Kowallis, fossils) 2009). that correlate this part of the formation to an U Fountain Basin nc o older Devonian formation called the Pinyon Peak Formation (fi g- Paradox Basinm p Emery a ure 13), which outcrops in thicker beds to the west of Rock Canyon. h Uplift g r e UTAH Figure 9. Small pebbles of dark quartzite and white vein quartz Fitchville Dolo. U ARIZONA p within the Tintic Quartzite. Weathered (orange-tan, lower right) and li ft unweathered (light gray) surfaces of this unit are shown. Pinyon Peak Fm. Figure 15. Fall colors grace the maples growing in the slope-form- ing Manning Canyon Shale (Mississippian) at the base of a cliff Zuni Uplift ? on Cascade Mountain. The cliffs of Cascade Mountain are formed Holbrook Maxfield Lst. from the light- and medium-gray beds of the Bridal Veil Limestone Basin with tree covered crags above the cliffs of the light-tan sandstones of the Bear Canyon Formation, both part of the Oquirrh Group NEW MEXICO (Pennsylvanian). 1 m Figure 14. Middle Paleozoic basins and uplift s showing the approximate location of Figure 14. Middle Paleozoic basins and uplifts showing the ap- Figure 11. Squaw Peak as seen from North Temple Drive. The Rock Canyon in the Oquirrh Basin (modifi ed from Hintze and Kowallis, 2009). Th is proximateperiod of uplift location and basin of subsidenceRock Canyon formed inmountains the Oquirrh that are Basincalled the (modified Ancestral orangish tan, gently dipping Tintic Quartzite is distinctive at the Figure 13. Contact between the Cambrian Maxfi eld Limestone and Devonian Fitch- fromRocky HintzeMountains. and Th Kowallis,e dashed line 2009).shows the This location period of the ofOquirrh uplift Basin and at thebasin time base of the peak and overlain by gray Paleozoic dolomites and ville Dolomite in Rock Canyon with a few feet of Pinyon Peak Formation between subsidenceit formed and formeddeposits accumulated. mountains Later that these are rocks called were thethrust Ancestral to the east duringRocky limestones. Figurethem (modifi 13. ed Contact from Clark between and others, the 2014). Cambrian Maxfield Limestone and Mountains.the The Sevier dashed orogeny. line shows the location of the Oquirrh Basin 8 5 Devonian Fitchville Dolomite in Rock Canyon with a few feet of at the time it formed and deposits accumulated. Later these rocks Pinyon Peak Formation between them (modified from Clark and were thrust to the east during the Cretaceous Sevier orogeny. others, 2014).

Figure 10. Rusty-colored Skolithos burrows in the Tintic Quartzite.

Figure 11. Squaw Peak as seen from North Temple Drive. The orangish tan, gently dipping Tintic Quartzite is distinctive at the base of the peak and overlain by gray Paleozoic dolomites and limestones. 5 6 IDAHO WYOMING B.J. Kowallis and L.C. Wald Rock Canyon

Oquirrh Basin NEVADA

Front Range Uplift

Rock COLORADO Canyon Eagle -- Central -- Taos Basin

U Fountain Basin nc o Paradox Basinm p Emery a h Uplift g r e UTAH U ARIZONA p Figure 15. Fall colors grace the maples growing in the slope-forming Manning Canyon Shale (Mississippian) at the base of a cliff on Cascade Mountain. The cliffs of Cascade Mountain are formed from the light- and medium-gray beds of the Bridal Veil Limestone with tree covered crags above the cliffs of the light-tan sandstones of the Bear Canyon li ft Formation, both part of the Oquirrh Group (Pennsylvanian). tionFigure of weak hydrochloric 15. Fall acid, whilecolors dolostones grace will only fizzthe if maplesthrust up over growing younger rocks (figures in the 16, 17 slope-formand 18). The thrust - you first scratch the surface or powder some of the rock. Chert fault and younger rocks underneath the thrust are not exposed in willing not fizzManning and is much harder Canyon than limestone Shale or dolostone. (Mississippian)Rock Canyon but they are at exposed the to thebase south near of the a cliff of Zuni Uplift Nephi, Utah and to the east in Spanish Fork Canyon. onMesozoic Cascade Mountain Mountain. Building – The Sevier The Orogeny cliffs of Cascade Mountain are formed Holbrook Followingfrom thethe end oflight- the Paleozoic and Era, Utahmedium-gray ceased to be the bedsAs the strata of were the folded Bridal and fractured, Veil some of Limestonethe rock units Basin western margin of the North American continent. During a long were deformed more plastically than others. The Ophir Shale, for spanwith of approximately tree covered 150 million years, crags fragments above of continental the example, cliffs is not of highly the fractured light-tan and has been substantially sandstones thick- andof oceanic the plates Bear collided Canyonwith western North Formation, America adding enedboth in some part parts of theof fold the and thinned Oquirrh or completely Groupsqueezed NEW MEXICO much of what is now Nevada, , Oregon, and Washing- out of other parts (figure 18). This is similar to what happens when ton.(Pennsylvanian). The collision of these fragments caused uplift and deforma- you squeeze or fold a tube of toothpaste—the paste gets thinned and tion in the rocks that had previously been deposited during the thickened in different parts of the tube. On the other hand, units Precambrian and Paleozoic. This mountain building event, called like the Tintic Quartzite behaved in a brittle manner, fracturing into Figure 14. Middle Paleozoic basins and uplifts showing the ap- the Sevier orogeny, created a high range of mountains in central pieces rather than flowing. Figure 18 shows the major fractures and Utah that we call the Sevier fold and thrust belt (Armstrong, 1968; faults in rock units of Rock Canyon. Dense fracturing and faulting proximate location of Rock Canyon in the Oquirrh Basin (modified DeCelles and Coogan, 2006). occur in the Tintic Quartzite compared to the other stratigraphic from Hintze and Kowallis, 2009). This period of uplift and basin units partly because it was in the core of the fold where deformation Erosion of these mountains left thick deposits of sandstone, was most intense and partly because the quartzite is simply more subsidence formed mountains that are called the Ancestral Rocky conglomerate, and shale off to the east (Young, 1966). None of brittle than the other rock units (figures 18 and 19). this erosional debris is visible in Rock Canyon, but the deposits Mountains. The dashed line shows the location of the Oquirrh Basin created by the erosion of the Sevier mountains can be seen in Mountain building ended about 40 million years ago and over the Spanish Fork Canyon a few miles to the south. What is visible next 20 million years the Sevier fold and thrust belt collapsed and at the time it formed and deposits accumulated. Later these rocks in Rock Canyon are the folds, faults, and fractures created when eroded, but left behind the structures formed during mountain were thrust to the east during the Cretaceous Sevier orogeny. the Precambrian and Paleozoic rocks, which had been deposited building as well as sediments shed to the east off of the mountains as several tens of miles to the west of Rock Canyon, were folded and they eroded away. 9

6 M. Milligan, R.F. Biek, P. Inkenbrandt, and P. Nielsen, editors 2019 Utah Geological Association Publication 48

Scale miles

(a) Pre-deformation 0 1 2 3 4 5

1 mi Oquirrh Formation

Manning Canyon Shale

Great Blue Limestone

Humbug Formation Gardison Limestone Maxfield Limestone Tintic Quartzite

(b) During thrusting

1 mi Oquirrh Formation

Manning Canyon Shale

Great Blue Limestone Great Blue Limestone Humbug Formation Humbug Formation Gardison Limestone Gardison Limestone Maxfield Limestone Maxfield Limestone Tintic Quartzite Tintic Quartzite

3 mi (c) Post Wasatch Fault development

2 mi

Utah Valley Squaw Peak Oquirrh Formation

1 mi Rock Canyon

Great Blue Limestone Valley fill sediments Sea Level Humbug Formation Gardison Limestone Maxfield Limestone Tintic Quartzite

-1 mi Oquirrh Formation Figure 16. Three stages in the development of the current geology of FigureRock 16. Th Canyon. ree stages in a) the Sedimentary development of therock current units geology prior of toRock the Canyon. Sevier A) Sedimen-orogenic tary rockdeformation. units prior to theb) SevierDeformation orogenic deformation. of the rocks B) Deformation due to ofthe the Sevier rocks due orogeny to -2 mi Great Blue Limestone the Seviercausing orogeny rock causing layers rock layersto be to bethrust thrust eastwardeastward several several 10’s of 10’skilometers of kilometersand to be folded and faulted. C) Formation of the Wasatch fault and infi lling of Utah Valley with material erodedand from to the be uplift folded ed side and of the faulted. fault. Th ec) approximate Formation position of theof Squaw Wasatch Peak is shownfault byand the dashedinfilling red line. of Modifi Utah ed fromValley Wald with (2007). material eroded from the uplifted side of

-3 mi the fault. The approximate position of Squaw Peak is shown by the dashed red line. Modified from Wald (2007).

10

7 B.J. Kowallis and L.C. Wald Rock Canyon

Figure 17. Folded Mississippian strata of the Gardison, Deseret and Humbug forma- Figuretion in Rock 17. Canyon. Folded Mississippian strata of the Gardison, Deseret, and Humbug formations in Rock Canyon.

The Wasatch Mountains and Wasatch Fault B

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Beginning about 20 million years ago western North America B

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i e a began to uplift , extend and pull apart due to warm rocks in the c t e c

d i Earth’s mantle rising buoyantly beneath the area. Th is extension a t Z e o d and uplift of the west continues up to the present day and is re- n Z e

o ( sponsible for the formation of the (Hin- n b

e e d tze and Kowallis, 2009). In the Rock Canyon area, this extension is ( b d in Figure 17. Folded Mississippiane strata of the Gardison, Deseret, responsible for the formation of the Wasatch Mountains and Utah d g and Humbug formationsd nin Rock Canyon. in o t Valley. A major fault zone, called the Wasatch fault, separates the g pFigure 17. Folded Mississippian strata of the Gardison, Deseret, Figure 17. Folded Mississippian strata of the Gardison, Deseret, n r o ande Humbug formations in Rock Canyon. uplift ed mountainand block Humbug from formations the down-dropped in Rock Canyon. valley. Over the t se p r r ve last 10 to 11 million years the mountains have been going up at a e d se ) r ve rate of about 0.6 to 1.0 mm/yr relative to the valley (Naeser and d ) others, 1983; Parry and Bruhn, 1987; Kowallis and others, 1990).

Th e uplift along the Wasatch fault causes stress to build up within the Earth and when the rocks cannot store up any more stress, it Mineral Fork Tillite is released in the form of earthquakes. Th e fault is composed of CoveredMineral Fork Tillite about 10 segments that break somewhat independently of each Slope Tintic Covered Covered Quartzite other (fi gure 20; Machette and others, 1991). Trenches dug across Slope Slope 20 ft Tintic Covered the segments of the Wasatch fault, including one at the mouth of Quartzite Slope Figure 19. Core20 ftzone of Rock Canyon fold. Top – photo of the core zone. Bottom Rock Canyon, have shown that earthquakes of moment magnitude –Figure Interpretive 19. drawingCore zone showing of Rockthe contact Canyon between fold. the Mineral Top – Forkphoto Tillite of andthe core 7.1 to 7.5 occur on each fault segment approximately every 2000 to Tinticzone. Quartzite Bottom with – Interpretive faults (red) and drawing bedding (gray). showing Bedding the has contact been completely between Figure 19. Core zone of Rock Canyon fold. Top – photo of the core destroyedthe Mineral in the centralFork Tillitebrecciated and zone. Tintic Modifi Quartziteed from Wald with (2007). faults (red) and 4000 years (Machette and others, 1991). With ten fault segments, zone. Bottom – Interpretive drawing showing the contact between bedding (gray). Bedding has been completely destroyed in the cen- we can expect that a large surface-rupturing earthquake will occur the Mineral Fork Tillite and Tintic Quartzite with faults (red) and tral brecciated zone. Modified from Wald (2007). every 200-400 years somewhere along the Wasatch fault. bedding (gray). Bedding has been completely destroyed in the cen- tral brecciated zone. Modified from Wald (2007). Figure 18. Geologic units mapped onto the profi le WEST EAST of Squaw Peak on the north wall of Rock Canyon. Figure 20. Wasatch fault segments as described by Machette and During the Sevier Orogeny, these rocks were others (1991). Each segment is capable of producing magnitude 7.0 thrust eastward several tens of miles and em- Figureto 7.5 earthquakes.20. Wasatch Onfault average segments earthquakes as described occur by atMachette intervals and of placed in the Rock Canyon area. Th e main faults othersbetween (1991). 500-2500 Each yearssegment on eachis capable segment. of producing This figure magnitude is modified 7.0 and fractures formed during this mountain tofrom 7.5 Hintze earthquakes. (2005). OnRock average Canyon earthquakes is located approximatelyoccur at intervals where of building 0event are0.1 shown in0.2 this sketch0.3 0.4 0.5 between 500-2500 years on each segment. This figure is modified of the north wall of the canyon. Th e the word Provo is on the figure. red box shows the area blownScale miles from Hintze (2005). Rock Canyon is located approximately where up in fi gure 19. Modifi ed 9 the word Provo is on the figure. Figurefrom Wald 18. (2007). Geologic units mapped onto the profile of Squaw Peak on the north wall of Rock Canyon. During the Sevier Orogeny, these rocks were thrust eastward several tens of miles and emplaced in the Rock Canyon area. The main faults and fractures formed during this9 mountain building event are shown in this sketch of the north wall of the canyon.0 The0.1 red box0.2 shows0.3 the0.4 area blown0.5 up in Figure 19. Modi- fied from Wald (2007). Scale miles 0 0.1 0.2 0.3 0.4 0.5 0 0.1 0.2 0.3 0.4 0.5 11 Figure 18. Geologic units mapped onto the profile of Squaw Peak on the north wall of Rock Canyon. During the Sevier Orogeny, these Scale miles 8 rocks were thrust eastward several tens of miles andScale emplaced miles in the Rock Canyon area. The main faults and fractures formed during this mountain building event are shown in this sketch of the north wall of the canyon. The red box shows the area blown up in Figure 19. Modi- Figure 18. Geologic units mapped onto the profile of Squaw Peak on the north wall of FigureRock Canyon. 18. Geologic During unitsthe Sevier mapped Orogeny, onto the these profile of Squaw Peak on the north wall of Rock Canyon. During the Sevier Orogeny, these fied from Wald (2007). rocks were thrust eastward several tens of miles and emplaced in the Rock Canyon area. Therocks main were faults thrust and eastward fractures several formed tens during of miles this and emplaced in the Rock Canyon area. The main faults and fractures formed during this mountain building event are shown in this sketch of the north wall of the canyon. The red boxmountain shows thebuilding area blown event up are in shown Figure in 19. this8 Modi sketch- of the north wall of the canyon. The red box shows the area blown up in Figure 19. Modi- fied from Wald (2007). fied from Wald (2007). 8 8 B

r M. Milligan, R.F. Biek, P. Inkenbrandt, and P. Nielsen, editors 2019 Utah Geological Association Publication 48

e

c

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i a t e d

Z o n e

( b e d d in g n o t p re se r ve d )

Mineral Fork Tillite

Covered FigureFigure 21. 21. Looking Looking north toward north Mount toward Mount along Timpanogos the Wasatch faultalong from the Slope Tintic Covered theWasatch road atop fault the alluvial from fanthe at road the mouth atop of the Rock alluvial Canyon. Noticefan at the the abrupt mouth change of Quartzite Slope inRock the slope Canyon. of the chain Notice link fencethe alongabrupt the changeroad. Th isin change the slopein the fenceof the line chainoccurs 20 ft wherelink itfence crosses along the fault the scarp road. created This during change the most in recent the large fence earthquake line occurs (which has been dated at about 600 years ago) on the Provo segment of the Wasatch fault. where it crosses the fault scarp created during the most recent large Figure 19. Core zone of Rock Canyon fold. Top – photo of the core Th ere is no break in the road here because fi ll was brought in to smooth out the slope. earthquake (which has been dated at about 600 years ago) on the zone. Bottom – Interpretive drawing showing the contact between Because the fi ll is not as fi rmly compacted as the rest of the alluvial fan sediments, the asphalt typically has cracks running across the road at this location. the Mineral Fork Tillite and Tintic Quartzite with faults (red) and Provo segment of the Wasatch fault. There is no break in the road bedding (gray). Bedding has been completely destroyed in the cen- here because fill was brought in to smooth out the slope of the road- tral brecciated zone. Modified from Wald (2007). 1890;way when Oviatt, it was1997). built. Reheis Because and others the fill (2014) is not suggested as firmly that compacted about 30,000as the restyears of ago the the alluvial basin fannow sediments, occupied bythe the asphalt Great typicallySalt Lake has cracks running across the road at this location. began to fi ll and Lake Bonneville was born. Th e lake grew until Figure 20. Wasatch fault segments as described by Machette and it covered almost one quarter of the state of Utah (Hintze and Figureothers 20. (1991). Wasatch Each fault segmentssegment as is described capable by of Machette producing and magnitudeothers (1991). 7.0 Eachto 7.5segment earthquakes. is capable of On producing average magnitude earthquakes 7.0 to 7.5 occur earthquakes. at intervals On of Kowallis, 2009). Th e lake reached its peak at about 18,000 years averagebetween earthquakes 500-2500 occur years at intervals on each of between segment. 500-2500 This figureyears on iseach modified segment. ago forming the highest prominent lake terrace. Th is terrace, Thfrom is fi gure Hintze is modifi (2005). ed from Rock Hintze Canyon (2005). isRock located Canyon approximately is located approximately where called the Bonneville terrace or shoreline, can be seen from the wherethe wordthe word Provo Provo is is on on the fifigure. gure. mouth of Rock Canyon (fi gure 22). Once the lake reached this 9 From studies of the trench across the fault at Rock Canyon (locat- level, a natural dam near the Utah-Idaho border was breached ed near the heliport on fi gure 6), the most recent large earthquake allowing water to fl ood and drain out to the north catastrophi- appears to have occurred approximately 600 years ago (Lund and cally onto the Snake River Plain (Reheis and others, 2014; Oviatt Black, 1998; Lund, 2005). Th is earthquake created a fault scarp (a and Jewell, 2016) causing the lake level to drop rapidly to a lower surface fault rupture) 6 to 10 feet (2-3 m) high, the remnants of level, called the Provo level, where it stabilized for several hundred which can still be seen along the road up to Rock Canyon (fi gure years. Continuing climate change caused regression of the lake to 21). Also, if you examine the outcrops of the Tintic Quartzite on the present level of the . Th e Provo-level terrace is the north side of the canyon (ENE of the heliport at the mouth of the fl at surface on which most of the the canyon on fi gure 6), you will fi nd that the outcrop of quartz- campus is built (fi gure 6). ite has been broken and fractured into many small pieces by the movement along the Wasatch fault. In addition to these lake terraces near the mouth of Rock Canyon, Figure 23. In the high elevations to the east, near the head of Rock visitors can also observe the change in the character of the canyon Canyon, the canyon opens up into a wide “U” shape sculpted out by glaciers during the Pleistocene ice ages. Lake Bonneville and the Pleistocene Ice Age as they hike to the east. Th e lower reaches of the canyon have a typical “V” shape produced by stream erosion, but farther into the About 1.8 million years ago the world-wide climate cooled signifi - canyon, just beyond the picnic and camping area on fi gure 6, it cantly creating large continental glaciers in North America and opens up into a wider “U” shape carved by glaciation (fi gure 23). Europe. Scientists studying this ice age have identifi ed several pe- riods of ice advances and retreats as the climate alternately cooled Recent Alluvial Deposits and warmed (Petersen and others, 1973). In Utah during periods Figure 22. Looking south from the parking lot at the mouth of Rock of cooler climate, mountain glaciers formed in the Wasatch and Aft er the disappearance of Lake Bonneville, sediments carried by theCanyon. stream The fl powerowing lineout ofpoles Rock are Canyon placed onwere the dumped Bonneville at the terrace, mouth Uinta mountains and large, fresh-water glacial lakes, called pluvial a flat surface created when Lake Bonneville was at its highest level. of the canyon forming an alluvial fan (see the fan-shaped deposit lakes, formed in the basins to the west (Atwood, 1909; Blackweld- The steep slope in the middle of the photo to the left of the pow- er, 1931; Madsen and Currey, 1979). Th e most recent, and one oner polesfi gure represents 6 outward the from approximate the mouth locationof the canyon). of the WasatchToday, manyfault of the largest of these pluvial lakes was Lake Bonneville (Gilbert, homesalong which as well the as mountainsthe Provo Templehave been and uplifted. Missionary Training Cen- 12 10 Figure 21. Looking north toward along the Wasatch fault from the road atop the alluvial fan at the mouth of Rock Canyon. Notice the abrupt change in the slope of the chain link fence along the road. This change in the fence line occurs where it crosses the fault scarp created during the most recent large earthquake (which has been dated at about 600 years ago) on the Provo segment of the Wasatch fault. There is no break in the road here because fill was brought in to smooth out the slope of the road- way when it was built. Because the fill is not as firmly compacted as the rest of the alluvial fan sediments, the asphalt typically has cracks running across the road at this location.

B.J. Kowallis and L.C. Wald Rock Canyon

Baker, A.A., 1973, Geologic map of the Springville quadrangle, Figure 21. Looking north toward Mount Timpanogos along the Utah: U.S. Geological Survey Map GQ-1103 (1:24,000). Wasatch fault from the road atop the alluvial fan at the mouth of Rock Canyon. Notice the abrupt change in the slope of the chain Baker,Figure A.A., 23. InHuddle, the high J.W., elevations and Kinney, to the D.M., east, 1949, near thePaleozoic head of Rock link fence along the road. This change in the fence line occurs Canyon,geology the of canyon north andopens west up sidesinto a of wide Uinta “U” Basin, shape Utah: sculpted Bulletin out by where it crosses the fault scarp created during the most recent large glaciersof the during American the Pleistocene Association ice of ages.Petroleum Geologists, v. 33, p. earthquake (which has been dated at about 600 years ago) on the 1161-1197. Provo segment of the Wasatch fault. There is no break in the road here because fill was brought in to smooth out the slope of the road- Bissell, H.J., 1974, Tectonic control of Late Paleozoic and Early way when it was built. Because the fill is not as firmly compacted sedimentation near the hinge line of the Cordille- as the rest of the alluvial fan sediments, the asphalt typically has ran miogeosynclinal belt: Tectonics and Sedimentation, the cracks running across the road at this location. Society of Economic Paleontologists and Mineralogists, v. Figure 22. Looking south from the parking lot at the mouth of Rock Canyon. The Figure 22. Looking south from the parking lot at the mouth of Rock SP22, p. 83-97. powerCanyon. line poles The are power on the line Bonneville poles terrace, are placed a flat surfaceon the created Bonneville when Lake terrace, Bon- neville was at its highest level. The steep slope in the middle of the photo to the left of Blackwelder, E., 1931, Pleistocene glaciation in the thea flat power surface poles represents created the when approximate Lake locationBonneville of the Wasatchwas at its fault highest along which level. theThe mountains steep slope have been in theuplifted. middle of the photo to the left of the pow- and Basin Ranges: Geological Society of America Bulletin, v. er poles represents the approximate location of the Wasatch fault 42, p. 865-922. along which the mountains have been uplifted. Bush, S., 1995, Rock Canyon watershed: A history and resource 10 review: Honors Thesis, Brigham Young University, 53 p. (AS 36.B752 B8812 1995). Christie-Blick, N., 1983, Glacial-marine and subglacial sedimen- tation Upper Mineral Fork Formation, Utah, in Molnia B.F., editor, Glacial-Marine Sedimentation: Springer, Boston, MA, p. 703-776. Christie-Blick, N., 1997, Neoproterozoic sedimentation and tecton- ics in west-central Utah, in Link, P.K, and Kowallis, B.J., editors, Proterozoic to recent stratigraphy, tectonics, and volcanology, FigureFigure 23. 23. In theIn highthe elevationshigh elevations to the east, to near the the east, head nearof Rock the Canyon, head theof canyonRock Utah, Nevada, and central Mexico: Brigham opens up into a wide “U” shape sculpted out by glaciers during the Pleistocene ice ages. Canyon, the canyon opens up into a wide “U” shape sculpted out by Young University Geology Studies, v. 42, part I, p. 1-30. terglaciers of the during Church the of Pleistocene Jesus Christ ice of ages.Latter-day Saints are built on Clark, D.L., Derenthal, D., Kowallis, B.J., and Ritter, S.M., 2014, this alluvial fan. As described earlier in this paper, the alluvial fan The major pre-Mississippian unconformity in Rock Canyon, is a place where flooding out of the canyon can still be a problem. central , Utah: Geology of the Intermountain West, v. 1, p. 1-5. SUMMARY Crittenden, M.D., Jr., Christie-Blick, N., and Link, P.K., 1983, Evi- Rock Canyon is a location where many of the events that shaped dence for two pulses of glaciation during the late Proterozoic Figure 22. Looking south from the parking lot at the mouth of Rock Utah’s geologic history can be studied and observed. It is an excel- Canyon. The power line poles are placed on the Bonneville terrace, in northern Utah and southeastern Idaho: Geological Society lent place for students, scout groups, families, or anyone interested a flat surface created when Lake Bonneville was at its highest level. of America Bulletin, v. 94, p. 437-450. The steep slope in the middle of the photo to the left of the pow- in learning more about geology to spend a few hours. The hiking Davis, F.D., 1983, Geologic map of the southern , er poles represents the approximate location of the Wasatch fault trails, picnic areas, rock climbing areas, rest rooms, along with along which the mountains have been uplifted. easy access and parking make this one of Utah’s best outdoor Utah: Utah Geological and Mineral Survey Map 55-A (1:100,000). 10 geologic laboratories. DeCelles, P.G., and Coogan, J.C., 2006, Regional structure and REFERENCES CITED kinematic history of the Sevier fold-and-thrust belt, central Armstrong, R.L., 1968, Sevier orogenic belt in Nevada and Utah: Utah: Geological Society of America Bulletin, v. 118, p. 841- Geological Society of America Bulletin, v. 79, p. 429-458. 864. Atwood, W.W., 1909, Glaciation of the Uinta and Wasatch Ersking, M.C., 1997, The Oquirrh Basin revisited: American Asso- Mountains: U.S. Geological Survey Professional Paper 61. ciation of Petroleum Geologists Bulletin, v. 81, p. 624-636. Baker, A.A., 1972, Geologic map of the Bridal Veil Falls quadran- Gilbert, G.K., 1890, Lake Bonneville: U.S. Geological Survey gle, Utah: U.S. Geological Survey Map GQ-998 (1:24,000). Monograph 1, 438 p.

13 M. Milligan, R.F. Biek, P. Inkenbrandt, and P. Nielsen, editors 2019 Utah Geological Association Publication 48

Granger, A.E., Sharp, B.J., Crittenden, M.D., and Calkins, F.C., Lund, W.R., 2005, Consensus preferred recurrence-interval 1952, Geology of the Wasatch Mountains east of Salt Lake and vertical slip-rate estimates: Review of Utah paleoseis- City: Utah Geological Society, Geology of the central Wasatch mic-trenching data by the Utah Fault Parameters Mountains, Utah, Guidebook to the Geology of Utah, no. 8, p. Working Group: Utah Geological Survey Bulletin 134, 109 p. 1-37. Lund, W.R., and Black, B.D., 1998, Paleoseismic investigation Hintze, L.F., 1978, Geologic map of the Y Mountain area, east of at Rock Canyon, Provo segment, Wasatch fault zone, Utah Provo, Utah: Brigham Young University Geology Studies, County, Utah: Utah Geological Survey Special Study 93, 21 p. Special Publication 5. Machette, M.N., Personius, S.F., Nelson, A.R., Schwartz, D.P., and Hintze, L.F., and Kowallis, B.J., 2009, Geologic : Lund, W.R., 1991, The Wasatch fault zone, Utah–segmenta- Brigham Young University Geology Studies Special Publica- tion and history of earthquakes: Journal of Struc- tion 9, 225 p. tural Geology, v. 13, p. 137-149. Jensen, J.M., 1924, Early History of Provo, Utah: Provo, Utah, Madsen, D.B., and Currey, D. R., 1979, Late Quaternary glacial self-published, available at Brigham Young University Harold and vegetation changes, area, B. Lee Library (F 834 .P8 J45x 1924), 182 p. Wasatch Mountains, Utah: Quaternary Research, v. 12, p. Jordan, T.E., and Douglass, R.C., 1980, Paleogeography and struc- 254-270. tural development of the Late Pennsylvanian to Early Perm- Matsch, C.L., and Ojakangas, R.W., 1991, Comparisons in dep- ian Oquirrh Basin, northwestern Utah, in Fouch, T.D., and ositional style of “polar” and “temperate” glacial ice, Late Magathan, E.R., editors, Paleozoic Paleogeography of west Paleozoic Whiteout Conglomerate (West Antarctica) and late central : Society of Economic Paleontologists Proterozoic Mineral Fork Formation (Utah), in Anderson, and Mineralogists, Rocky Mountain Section, West-Central J.B., and Ashley, G.M., editors, Glacial marine sedimentation: United States Paleogeography Symposium I, p. 217-238. Paleoclimatic significance: Geological Society of America, Kay, M., 1951, North American geosynclines: Geological Society Special Paper 261, p. 191-206. of America Memoir 48, 143 p. Naeser, C.W., Bryant, B., Crittenden, M.D., Jr., and Sorensen, M.L., Kluth, C.F., 1986, Plate Tectonics of the Ancestral Rocky Moun- 1983, Fission-track ages of apatite in the Wasatch Mountains, tains: Part III, Middle Rocky Mountains: Paleotectonics and Utah: an uplift study: Geological Society of America Memoir Sedimentation in the Rocky Mountain , United States: 157, p. 29-36. American Association of Petroleum Geologists Memoir 41, p. Ojakangas, R.W., and Matsch, C.L., 1980, Upper Precambrian (Eo- 353-369. cambrian) Mineral Fork Tillite of Utah: A continental glacial Kowallis, B.J., and Walker, B., 2009, Rock Canyon field guide: and glaciomarine sequence: Geological Society of America Brigham Young University Department of Geological Scienc- Bulletin, Part I, v. 91, p. 495-501. es, 1 folded sheet. Oviatt, C.G., 1997, Lake Bonneville fluctuations and global climate Kowallis, B.J., Ferguson, J., and Jorgensen, G.J., 1990, Uplift along change: Geology, v. 25, p. 155-158. the Salt Lake segment of the Wasatch fault from apatite and Parry, W.T., and Bruhn, R.L., 1987, Fluid inclusion evidence for zircon fission track dating in the Little Cottonwood stock: Nu- minimum 11 km vertical offset on the Wasatch fault, Utah: clear Tracks and Radiation Measurements, v. 17, p. 325-329. Geology, v. 15, p. 67-70. Lee, W.T., 1918, Early Mesozoic physiography of the southern Rocky Petersen, M.S., Rigby, J.K., and Hintze, L.F., 1973, Historical geology Mountains: Smithsonian Miscellaneous Collections, v. 69. of North America: Dubuque, Iowa, Wm. C. Brown Co., 193 p. Link, P.K., Miller, J.M.G., and Christie-Blick, N., 1994, Glacial-ma- Peterson, D.O., and Clark, D.L., 1974, Trace fossils Plagiogmus and rine facies in a continental rift environment: Neoproterozoic Skolithos in the Tintic Quartzite (Middle Cambrian) of Utah: rocks of the Cordillera, in Deynoux, Journal of Paleontology, v. 48, p. 766-768. M., Miller, J.M.G., Domack, E.W., Eyles, N., Fairchild, I.J., Reheis, M.C., Adams, K.D., Oviatt, C.G., and Bacon, S.N., 2014, and Young, G.M., editors, Earth’s Glacial Record: Cambridge Pluvial lakes in the of the western United States–a University Press, p. 29-46. view from the outcrop: Quaternary Science Reviews, v. 97, p. Lochman-Balk, C., 1976, The Cambrian section of the central 33-57. Wasatch Mountains, in Hill, J.G., editor, Geology of the Cor- Stokes, W.L., 1976, What is the Wasatch Line?, in Hill, J.G., editor, dilleran Hingeline: Rocky Mountain Association of Geologists Geology of the Cordilleran Hingeline: Rocky Mountain Asso- – 1976 symposium, p. 103-108. ciation of Geologists–1976 Symposium, p. 11-25.

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Varney, P.J., 1976, Depositional environment of the Mineral Fork Formation (Precambrian), Wasatch Mountains, Utah, in Hill, J.G., editor, Geology of the Cordilleran Hingeline, Rocky Mountain Association of Geologists – 1976 symposium, p. 91-102. Ver Wiebe, W.A., 1930, Ancestral Rocky Mountains: American Association of Petroleum Geologists Bulletin, v. 14, p. 765- 788. Wald, L.C., 2007, Structural analysis of Rock Canyon near Provo, Utah: M.S. thesis, Brigham Young University, 63 p. Wilson, M.L., 1988, Analysis of a proposed economic develop- ment: The case of Heritage Mountain: M.S. Thesis, Brigham Young University, Provo, Utah, 123 p. (G1.02 .W55 1988). Ye, H., Royden, L., Burchfiel, C., and Schuepbach, M., 1996, Late Paleozoic deformation of interior North America: the greater Ancestral Rocky Mountains: American Association of Petro- leum Geologists Bulletin, v. 80, p. 1397-1432. Young, R.G., 1966, Stratigraphy of coal-bearing rocks of Book Cliffs, Utah-Colorado: Utah Geological and Mineral Survey Bulletin 80, p. 7-22.

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