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Home , A Bigger Grand Canyon, Canyon, Grand Canyon Supergroup, Grand Wash Cliffs, John Strong Newberry, Stream capture

CRevolution 2: Origin and Evolution of the System II themed issue

A pre–21st century history of ideas on the origin of the Grand

Wayne Ranney* 255 E. Hutcheson Drive, Flagstaff, 86001, USA

ABSTRACT INTRODUCTION from the previous one and a half centuries of study (Young and Spamer, 2001; Beard et al., From the mid-nineteenth through twen- The is a world-renowned land- 2010; Karlstrom et al., 2012). tieth centuries, geologists attained a good, form that is visited each year by over 4.5 million However, modern attempts to unravel the ori- if imperfect, view of the development of the people, almost half of whom arrive from another gin of Earth’s largest erosional feature, or the and the Grand Canyon. country. Geologists continue to debate the spe- complex history of one of our continents most Beginning in the late 1850s and continu- cifi c process or combination of processes that important , are necessarily framed by the ing through the 1880s, fundamental con- have acted to form it and precisely when exca- fi ndings obtained from much earlier research cepts such as fl uvialism, antecedence, and vation commenced. The canyon’s tremendous efforts. Many seminal conclusions from the superposition were invoked to explain the size along with its striking color and texture are nineteenth and twentieth centuries serve to development of the Colorado River. Early unequaled on Earth. Results from a combina- constrain modern studies about how the Colo- proposals envisioned the Colorado River tion of fi ve independent factors have worked rado River or its ancestors helped to carve the as “old” relative to the surrounding land- together to create this unique landscape: (1) a Grand Canyon. For example, the Muddy Creek scape. Challenges to antecedence were slow thick stack of sedimentary rock; (2) variably and constraint at the foot of the Grand Wash Cliffs to emerge, and it remained the most viable vividly colored strata; (3) epeirogenic uplift that showed that the modern Colorado River could theory into the early twentieth century. At raised the rocks without signifi cant deforma- not have existed before ca. 6 Ma (Longwell, that time two distinct periods (and styles) tion; (4) deep dissection by a continental-scale 1946; Lucchitta, 1966), while other studies far- of were proposed: a cycle river system; and (5) location within a modern ther upstream in the state of Colorado suggested with lateral stripping of strata and a canyon arid belt where rocks are not encumbered by that the river there might be as old as ca. 20 Ma cycle of deep, vertical dissection. Beginning vegetation or extreme chemical . (Hunt, 1956). Modern workers use these base- in the 1930s, newer ideas proposed that the Remove any one of these fi ve factors, and the line fi ndings to help focus their research efforts Colorado River was “young,” having been Grand Canyon, as we know it, would not exist to resolve this still intractable problem. This integrated by sequential basin spillover, the (Ranney, 2012). paper presents a summary of the evolution of timing of which was constrained by interior In spite of the intrigue, mystery, and enigmas geologic thinking on the origin of Grand Can- basin deposits lying across the mouth of the that remain, much is known about the canyon’s yon, based on work before 2000. It is hoped that Grand Canyon at the Grand Wash Cliffs (the development and formation, resulting from the perspectives from the nineteenth and twen- Muddy Creek constraint). The fi eld entered more than 150 years of scientifi c research (Karl- tieth centuries can be a valuable reference point a period of uncertainty related to the con- strom et al., 2012). Numerous workers have for future workers who will attempt to unravel fl icting evidence for an old (Paleogene) river sought to understand the origin of the Grand the mysteries that remain. upstream from the Grand Canyon versus a Canyon, and one of the basic underpinnings young (Neogene) river at Grand Wash Cliffs. of this understanding is that the canyon owes PRE-SCIENTIFIC BACKGROUND Results from a symposium convened in 1964 its existence wholly to the history and evolu- offered a solution with a poly-phase his- tion of the Colorado River (Newberry, 1861) or Native peoples of the American Southwest tory for the Colorado River. The poly-phase its ancestors. When geologists fi rst gazed into likely discovered the Grand Canyon shortly theory suggested that the river formed in a the Grand Canyon, they saw evidence for the after the continent was colonized some 13,000 complex manner by the integration of two intimate relationship between the canyon land- years ago. These natives left no written record separate drainages, although some aspects scape and the Colorado River. From this initial of their impressions but did impart oral legends became untenable. Efforts to resolve out- observation, a good, if incomplete, view of the that were the fi rst attempts by humans to com- standing dilemmas from 1964, such as the evolution of both the river and the canyon had prehend the vast scale and origin of the canyon. ages of the Colorado River and the Grand been achieved. By the end of the twentieth cen- Passed down through the millennia to today’s Canyon, have ultimately led to a modern tury, geologists were poised to move beyond the modern tribes, these legends are non-scientifi c resurgence in research. technical and theoretical limitations inherited but demonstrate nevertheless how humans in

*Email: [email protected]

Geosphere; April 2014; v. 10; no. 2; p. 233–242; doi:10.1130/GES00960.1; 5 fi gures. Received 12 July 2013 ♦ Revision received 4 January 2014 ♦ Accepted 5 February 2014 ♦ Published online 17 March 2014

For permission to copy, contact [email protected] 233 © 2014 Geological Society of America

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pre-scientifi c sought to explain ply of troops engaged in the Mormon campaign. opposite sides of the deepest chasm showed per- such an immense . The legends only Ives wrote confl icting statements about his fect correspondence of stratifi cation . . .” (Fig. coincidentally mirror later scientifi c theo- reaction to seeing such a deeply dissected and 1). This meant to him that the Colorado River ries, but in some instances they invoke a close parched landscape, but he can be considered as was not merely following a preexisting rift or genetic association between the Colorado River one of the last persons from the pre-scientifi c fi ssure but that it was the instrumental agent and the canyon. period to view the canyon in a mostly negative that created the canyon (Newberry, 1861, Part People of European descent fi rst saw the way. He referred to the canyon as “valueless” III, p. 46). He made the seminal observation Grand Canyon in 1541 when members of the and stated that it would be “forever unvisited about Grand Canyon, still the basis of all mod- Coronado Expedition sought a way to resupply and undisturbed” (Ives, 1861, Part 1, p. 110). ern studies that “the high and perpendicular their expedition by river from the Gulf of Cali- His response to the landscape reveals how some walls belong to a vast system of erosion, and are fornia. Sparse but illuminating written accounts people, even today, can react to the southwest- wholly due to the action of water” (Newberry, show that the Spaniards were ill-prepared to ern landscape when a geologic perspective is 1861, Part III, p. 45). This concept, known as comprehend the vast excavated space or sig- lacking. The few positive comments that Ives fl uvialism, was increasingly being applied in nifi cance of the landscape laid out before them. penned about the Grand Canyon may have orig- the mid-nineteenth century to refute the anti- Descriptive passages assert that the canyon was inated from the opposing reactions expressed by quated views of diluvialism. To this day, New- larger than fi rst conceived and that some boul- his saddle-mate and geologist colleague, New- berry’s fl uvialism remains the principal datum ders within it were “bigger than the great tower berry, upon viewing the same landscape. for how the Grand Canyon was formed. The of Seville” (Winship, 1922, p. 36). In the year Newberry was trained in medicine but was central idea that the Colorado River is respon- 1541, this tower was 282 feet high, less than the also schooled in natural sciences, especially sible for the carving of the Grand Canyon has thickness of the Kaibab that geology and botany. As the expedition explored never seriously been challenged, although some caps the rim of the canyon. Disinterested and Grand Canyon, Newberry came to recognize a workers have recently invoked signifi cant exca- perhaps dispirited, no Spaniard would revisit critical relationship between the canyon and the vating by ancient predecessors of the modern Grand Canyon for 235 years. Colorado River: “…examining with all possible river (Flowers et al., 2008; Wernicke, 2011). This initial encounter between Europeans care the structure of the great cañons which In 1859, Newberry was employed as geolo- and the American Southwest initiated a long we entered, I everywhere found evidence of the gist on a second exploration journey called the period in which non-geologists interacted with exclusive action of water in their formation. The San Juan Exploring Expedition, led by Captain the landscape in mostly negative ways. For 320 years, numerous conquistadors, fur trap- pers, miners, and explorers came to the Grand Canyon with the hope of fi nding precious met- als, beaver pelts, lost souls, or to attain fame. They could not imagine or foresee the scientifi c treasure that lay at their feet, for the science of geology was far off in the future. These explor- ers viewed the canyon as a barrier to travel at best, and often deemed it worthless and unwor- thy of a repeat visit. None of the people from this pre-scientifi c period in American history returned for a second visit. However, subse- quent visits from those with geologic training would change forever the way people related and reacted to the canyon.

FUNDAMENTAL CONCEPTS— MID-NINETEENTH CENTURY

Fluvialism—John Strong Newberry

It was a vanguard of early Grand Canyon geologists who fi rst announced to the world that this stupendous gorge was not simply a barrier to travel but rather a feature of world-class signifi - cance (Ranney, 2013). John Strong Newberry is credited as the fi rst geologist to view the Grand Canyon. He was part of the Colorado Explor- ing Expedition (1857–1858) commonly called the Ives Expedition for commanding offi cer Lieutenant , who headed Figure 1. Cross section of the Grand Canyon showing the correspondence of strata on a small Army contingent up the lower Colorado either side of the Colorado River (adapted from Newberry, 1861, and taken from Ranney, River to determine its navigability for the resup- 2012, p. 54).

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John N. Macomb. Serving on this overland Brown’s Hole. Here the Green River becomes upwarp: “Though the entire region has been expedition to the confl uence of the Green and suddenly entrenched 500 m in less than a kilo- folded and faulted on a grand scale, these dis- Grand (Colorado) rivers, Newberry com- meter at the entrance to the Canyon of Lodore. placements have never determined the course mented, “Though valueless to the agricultural- After reviewing the evidence, Powell settled of the . . . All the facts concerning the ist; dreaded and shunned by the emigrant, the on antecedence for the origin of the Green relation of the water-ways of this region to the miner, and even the adventurous trapper, the River, suggesting that as the Uintah mountains, hills, cañons, and cliffs, lead to the is to the geologist a para- were slowly uplifted, the river’s course was not inevitable conclusion that the system of drain- dise. Nowhere on the earth’s surface, so far as defl ected around them (Fig. 2). Thus the river age was determined antecedent to the faulting, we know, are the secrets of its structure so fully was antecedent to the mountainous landscape and folding, and erosion, which are observed” revealed as here” (Newberry, 1876, p. 54). With that surrounds it: “The river did not its way (Powell, 1875, p. 198). this pronouncement, Newberry sounded a siren down through the mountains, from a height of Powell’s ideas regarding antecedent theory call that geologists could not ignore. many thousand feet above its present site, but led to widespread acceptance by his contempo- . . . as the fold was lifted, it cleared away the raries. He did, however, remark that he struggled Antecedence—John Wesley Powell obstruction by cutting a cañon, . . . The river between an antecedent or superposed origin of preserved its level [as] the mountains were lifted the Green River. He and a colleague, Archibald Fluvialism was never challenged in relation to up” (Powell, 1875, p. 153). Marvine, had together found evidence for super- the formation of Grand Canyon, but the manner Powell terminated his second expedition at posed formation in the , in which it evolved occupied the mind of John the mouth of , where he embarked and Powell stated that he initially was inclined Wesley Powell, the second geologist to view on an overland expedition to the north side of toward that view for the Green River. However, and remark upon the canyon. He embarked on Grand Canyon, giving him a fantastic vantage when Marvine questioned Powell about why he two historic boat trips that began on the Green from which to examine the geology of this settled on an antecedent origin for the Green River in 1869 and 1871. Powell was intrigued region. He was in full agreement with New- River Powell stated that, “the [superposition] by the way the river plunged headlong into berry on a fl uvial origin for the landscape in hypothesis was found to be not only inadequate resistant Proterozoic quartzite on the northern Grand Canyon and after settling on an anteced- to the explanation of facts, but to be entirely fl ank of the Uintah Mountains, rather than take ent origin for the Green River, Powell perhaps inconsistent with them” (Powell, 1875, p. 166). a seemingly easier course to the east through the became too inclined to suggest a similar origin Thus an antecedent origin for rivers on the Col- softer rocks and much lower country located in for the Colorado River as it crossed the Kaibab orado Plateau remained virtually unchallenged throughout much of the nineteenth century. Ulti- mately, however, antecedence would lose favor with some geologists as the formative process in determining the course of the Green and Colo- rado rivers. Even in Powell’s day, modifi cations to it were already beginning.

Superposition and the Great Denudation— Clarence E. Dutton

One of the fi rst variations regarding ante- cedence came from Powell’s protégé, Clarence Dutton, a Yale-educated Army offi cer whom Powell befriended in and recruited for geologic work in the West. Dutton was an astute observer of the landscape and eventu- ally sought to elaborate on the manner in which Powell’s antecedent river was positioned on the landscape. First, he defended antecedence: “The river is older than the structural features of the country. Since it began to run, mountains and have risen across its track and those of its . . . As these irregularities rose up, the streams turned neither to the right nor to the left but cut their way through in the same old places” (Dutton, 1880, p. 16). After stating this support for antecedence, Dutton sought to explain how the specifi c place- ment of the river might have been positioned Figure 2. Cartoon depicting the sequential development of an ante- on the landscape. He looked to the Green River cedent with: (A) a stream meandering across a subdued ter- Formation, an Eocene-age lake deposit found rane; and (B) slow uplift of the same terrane such that the river at the foot of the Uintah Mountains. Accord- maintains its position, carving a canyon (from Ranney, 2012, p. 57). ing to Dutton, when the lake water drained

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away, the Green River found a course through rock was removed laterally toward the north dur- the construction of the Nankoweap Trail leading the diminutive swales and depressions on top ing the Great Denudation, relative to the amount from the to the Colorado River of the lacustrine beds. Subsequent uplift of the removed in the vertical excavation of the deep and placed Charles Walcott in charge of the sur- Uintah Mountains then caused the river to carve (Powell, 1875, p. 208). While ponder- vey party that spent the next 72 days exploring down into the deeply buried quartzite to create ing this observable fact, Dutton noted how ero- and mapping geology from Nankoweap Canyon the Canyon of Lodore. Powell had previously sion had acted to create “a great stairway” of to near present-day Hance Rapid. Structurally coined the term superposition to describe such progressively rising strata to the north of Grand and stratigraphically, this is one of the most var- a process (Powell, 1875, p. 166), and Dutton Canyon. (The idea ultimately led to the name ied and interesting sections of the canyon. Here showed a continued respect toward him: “What of the .) Later enhancements to Walcott recognized and named the fault then determined the present distribution of the Dutton’s original ideas would determine that (Walcott, 1890, p. 50), which was a more deeply drainage? The answer is that they were deter- the Great Denudation was initiated during the exposed expression of the East Kaibab mono- mined by the confi guration of the old Eocene Sevier and Laramide orogenies, followed by a cline, named and previously studied by Pow- Lake bottom at the time it was drained” (Dut- much later period of Neogene vertical dissec- ell and Dutton. This fault and fold system has ton, 1880, p. 17). Thus we see how Dutton tion. Dutton added substance to the prior work experienced a complex history, known to have offered both a validation and a refi nement to of his heroic predecessors. at least 3200 m of late Proterozoic normal off- Powell’s antecedent theory (Fig. 3). set, overprinted by 800 m of Laramide reverse Dutton made other contributions closer to CHALLENGES TO ANTECEDENCE— movement (Timmons et al., 2003). Grand Canyon by noting two vastly different LATE-NINETEENTH CENTURY What concerned Walcott was the evidence styles of erosion that occurred on the landscape for structural fl exing of the strata adjacent to the there. The fi rst he called “the Great Denuda- The Butte Fault and the Relative Age of the Butte fault, and he wondered if this would have tion,” referring to the lateral stripping of post- Kaibab Uplift—Charles D. Walcott required fault movement before thick sections Paleozoic strata away to the north. The second of Mesozoic strata were eroded: “It is diffi cult he called “the Great Erosion,” representing Challenges to antecedence came subtly at fi rst to understand how the cañon could have existed the deep vertical dissection that sliced through (Walcott, 1890) and forcefully by the close of even to a limited depth, in its present position, at Paleozoic strata within the canyon (Dutton, the century (Emmons, 1897). Alternative expla- the time of the elevation of the Kaibab Plateau. 1882). This distinction, noticed by Powell on his nations began to emerge after Powell identifi ed An explanation more in accord with observa- overland expedition in 1871–1872, concerned the eastern section in Grand Canyon as critical tions on the Eastern Kaibab displacement is the way in which a vastly superior amount of to the next line of study. In 1882, he undertook that while the uplifting of the plateau and the East Kaibab displacement were progressing, the Colorado River was cutting its down through the Mesozoic groups that then rested on the Paleozoic rocks in which the present cañon is eroded, and that, instead of cutting a chan- nel down through the and of the Paleozoic, as the plateau was elevated, it was cutting through the fold in the superjacent Mesozoic rocks (Walcott, 1890, p. 60). Walcott offered this evidence to show how the present- day canyon could not have been cut before the uplift of the Kaibab Plateau. This initial view of an older age for plateau uplift would eventually become known as the Laramide orogeny. Walcott, still appearing to defer to the prestige of his mentor, continued to envision the course of the river as essentially changeless through time. But he could not dis- miss the evidence from the Butte fault for the timing of the uplift of the Kaibab Plateau, likely occurring before the present-day canyon was cut. Three periods of uplift would eventually be proposed for the region, and it is from the work of Walcott that the debate on the timing of Pla- teau uplift commenced.

Antecedence Attacked—Samuel F. Emmons Figure 3. Cartoon depicting the sequential development of a super- posed stream with: (A) a stream meandering across a subdued ter- U.S. Geological Survey geologist Samuel rane underlain with soft ; and (B) uplift and denudation F. Emmons had completed mapping in the of the soft down into a preexisting topography (from Ran- Green River and Uintah area as part ney, 2012, p. 59). of the Hayden Survey in 1871. But almost 30

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years later, he presented a strident challenge to Davis reaffi rmed the two cycles of erosion his many observations on the evolution of the antecedence in the journal Science (Emmons, proposed by Dutton and added that they were landscape: “The most emphatic lesson that the 1897). Emmons recalled how the Green River an imperative based on the evidence. He chose canyon teaches, is that it is not a very old fea- Formation was seen to lap horizontally onto the alternate names for them, calling the fi rst the ture of the earth’s surface, but a very modern upturned edge of the Uintah Mountains. This plateau cycle for the lateral stripping of strata one; that it does not mark the accomplishment strongly suggested to him that the Uintah uplift (Dutton’s Great Denudation) and the latter the of a great task of earth sculpture, but only the was older than the lacustrine sediments: “What, canyon cycle of vertical dissection into the beginning of such a task; and that in spite of then, became of the river while these 8,000 feet strata (Dutton’s Great Erosion). Davis went its great dimension, it is properly described as of Tertiary sediments were being deposited? It a step further, however, and argued that two a young valley” (Davis, 1909, p. 346). Here could hardly have continued its course at the separate periods of uplift facilitated the two ero- marks a paradigm shift from earlier ideas, bottom of the Tertiary lake . . . its bed must have sional cycles, with two different kinds of land- which held that an immense landscape must been fi lled with sediments . . . and when the forms resulting from each—linear have necessarily formed through an immense lakes were fi nally drained, it is hardly conceiv- in the plateau cycle and sheer-walled gorges in period of time. Davis argued that the Grand able that, in redetermining its course across 150 the canyon cycle (Davis, 1901, p. 136). Canyon was a geologically young feature. miles of Tertiary beds . . . it should have attacked Another fi nding was the manner in which nor- Other notable geologists offered conjectures the fl anks of the Uintah range . . . at the same mally dry and much smaller streams while participating on expeditions to the region, point it should have entered before” (Emmons, in the Grand Canyon entered the Colorado notably Willis T. Lee (1906), Douglas W. John- 1897, p. 20). River at . Upon making this observation, son (1909), and H.H. Robinson (1910). But Emmons’ reasoning was sound and per- Davis surmised that “corrasion [deepening] of fresh ideas languished until the 1930s. haps illustrates how prior fame can oftentimes the canyon must at present be proceeding at a obscure the more practical fi ndings of those slower rate than at some earlier time” (Davis, Basin Spillover—Eliot Blackwelder not as well revered. Powell could only respond 1901, p. 168). Davis also showed how ante- that his own line of reasoning in accepting ante- cedence could not explain every aspect of the By the 1930s, it became apparent that the age cedence was too far in the past to recall why he modern drainage confi guration: “The facts now and formation of the Grand Canyon could be settled on it, and apparently the nascent debate on record . . . warrant the consideration of at not be understood without a knowledge of the ended there. But Emmons had delivered a viable least one hypothesis alternative to the theory of history of the Colorado River. Newberry had alternative to antecedence, which by the end of antecedence, as an explanation for the origin of initially shown the close relationship between the twentieth century was still a favored theory, the drainage lines in the Grand Canyon district. the two features, with subsequent workers seek- but one that would later in the century be more I do not on the one hand consider the anteced- ing to know more about the age of the uplifts roundly challenged. ent origin of the Colorado disproved, but, on relative to the dissection of the canyons. No the other hand, such an origin does not seem geologist, with perhaps the exception of Davis, EVIDENCE FOR A YOUNG compulsory. The chief objection to the theory of had expressed the possibility that the Colorado GRAND CANYON—EARLY antecedence is not that rivers cannot saw their River was young, and most workers inferred a TWENTIETH CENTURY way through rising mountains . . . but rather Paleogene age for it. Eliot Blackwelder, pro- that this theory makes a single stride from the fessor of geology at Stanford, would change of the Grand Canyon— beginning to the end of a long and complicated this. He completed work along the river from William Morris Davis series of movements and , overlooking the Mexican border to the mouth of the Grand all the opportunities for drainage modifi cations Canyon and wondered why, if the Colorado The twentieth century would begin with on the way” (Davis, 1901, p. 166). Davis argued was an old river system, had it not captured the geologists taking to the fi eld in horse and buggy that antecedence was too simple an explana- interior basins that adjoined it near Las Vegas wagons, and it would end with astronauts travel- tion given the many complications he observed (Blackwelder, 1934). These basins were only a ing to the Moon and scientists encircling Earth here, such as the numerous displacements on few kilometers from the main trunk stream yet using global positioning system technology. faults and folds and the possible reorganization remained closed to the sea. He also noted how Geologists had studied the canyon for over 40 of the drainage system during the plateau cycle the river fl owed through seemingly unrelated years and were drawn to it by the enthusiastic of erosion. basins on its way from the Rockies to the sea: and vivid reports generated by their earlier col- In addition, Davis classifi ed the major side “The Colorado River is in many ways an anom- leagues. At this time, antecedence was a favored streams in Grand Canyon as having formed in alous stream, but perhaps in no respect more so theory for the origin of the Colorado River sys- a manner inconsistent with antecedence. Cata- than in the course which it pursues. Rising in the tem (and by extension, the Grand Canyon), in ract (Havasu) Creek was a consequent stream high mountains of and Colorado, it spite of certain limitations highlighted by some. (one that fl owed down an existing gradient), traverses a series of wide basins, each of which William Morris Davis was the fi rst geologist to but Paria Creek and Kanab Creek were obse- seems to be an entity almost unrelated to the undertake an examination of the canyon land- quent ones (fl owing against stratigraphic dip), others . . . It runs south for hundreds of miles, scape at the dawn of the new century. He made while the was subsequent then for no obvious reason turns abruptly west, three excursions to the region, arriving fi rst in (paralleling strike), except in its last 40 miles, crosses , and again turns due June 1900, when he completed a 23-day journey where it becomes obsequent; and House Rock southward in an erratic course” (Blackwelder, by horseback and wagon that took him to both Valley also was a subsequent stream. This was 1934, p. 554). rims as well as the interior of the canyon. Dur- an affi rmation that the Colorado River was a Blackwelder was laying the groundwork for ing this and later trips, he offered many cogent complex drainage that foretold of a complex his grand assault on the perceived antiquity of and innovative remarks about the canyon’s for- evolution. In a later paper, given at the Ameri- the river. He noted that the river’s course from mation and its geomorphology. can Geographical Society, Davis summarized the Rocky Mountains to the sea went through

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a series of open basins, separated by bedrock the way to the Gulf of , thus forming gin and history of the Colorado River is frankly ridges where the drainage fl owed through nar- a chain of lakes strung upon a river” (Black- theoretical. Science advances not only by the row canyons. He reasoned that basin spillover welder, 1934, p. 562). discovery of facts but also by the proposal and (Fig. 4) might be a preferred process to create This was one of the fi rst contrary thoughts consideration of hypotheses, provided always the river’s course: “It is reasonable to infer that, presented regarding the age of the river. Black- that they are not disguised as facts. This view as the region bulged upward, the local streams welder dared to challenge the views of his will not meet with general acceptance. There on the higher and more northerly mountains heroic predecessors by highlighting what he had are doubtless many facts unknown to me that extended themselves, forming lakes in the near- observed along the course of the lower Colorado will be brought forward in opposition. Perhaps est basins. As this infl ux exceeded evapo- River. He agreed with Davis that the Colorado their impact will prove fatal to the hypothesis. In ration . . . the lakes rose until they overfl owed River might have experienced a complex evo- any event, the situation will be more wholesome, the lowest points of their rims and spilled into lution, but by inference may have taken too now that we have two notably different explana- adjacent basins. In time, enough excess outfl ow great a step in applying the same thoughts for tions, than it was when it was assumed by all may have developed to fi ll a series of basins all the upper river: “The foregoing sketch of the ori- that the river had existed continuously since middle or early Tertiary time. It seems to me that the new hypothesis is harmonious with most of the important facts now known about the geol- ogy and history not only of the Colorado River but of the Western States in general” (Black- welder, 1934, p. 564). Eliot Blackwelder was among the fi rst to open the door to a new way of thinking about the age and history of the Colorado River, which ultimately led to further study of and support for a young Colorado River.

The Muddy Creek Constraint— Chester Longwell

When Boulder (now Hoover) was under construction, geologists were eager to study the soon-to-be-inundated fl oor of the reservoir, knowing that rocks related to the evolution of the Colorado River and Grand Canyon would not be available for future study. Chester Lon- gwell of Yale (later Stanford) University had worked in the nearby Muddy Mountains and became interested in the geology of the Boul- der reservoir area. He was struck by a fact that was becoming more and more obvious to those involved with studies of the river—that a date no more precise than Paleogene to late Neo- gene could be ascribed to it and highlighted this dilemma in his 1946 paper: “One of the major unsolved problems of the region is the date of origin of the river itself . . . Geologists who have no direct acquaintance with the region will be at a loss to understand so wide a divergence in interpretation” (Longwell, 1946, p. 817). Longwell studied rocks near the Grand Wash Cliffs where the Colorado River exits the Grand Canyon at the western edge of the Colorado Pla- teau. Here, a mid- to late Miocene half-graben had accumulated deposits known as the Muddy Creek Formation, which lay strewn across both sides of the Colorado River. Longwell did not fi nd detritus within the Muddy Creek Formation Figure 4. Cartoon depicting the sequential spillover from formerly that could be identifi ed from known bedrock closed basins. Blackwelder envisioned such a scenario from the exposures upstream. His interpretation was that Rocky Mountains to the Gulf of California to integrate a young when the Muddy Creek Formation was depos- Colorado River (from Ranney, 2012, p. 102). ited, the Colorado River could not have been

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in its present course at the Grand Wash Cliffs: titled, “Cenozoic Geology of the Colorado Pla- posed a different solution to the Muddy Creek “There is no possibility that the river was in teau” (Hunt, 1956). This was a synthesis of problem, having the Colorado River make its its present position west of the plateau during known information about the river and the land- way through most of Grand Canyon but then Muddy Creek time. The suggestion occurs that scape it traversed, from the Uintah Mountains percolating beneath the Plateau in a stream, either permanent or intermittent, may to the Mojave Desert. Hunt likely was feeling western Grand Canyon with the water emerg- have developed on the site of the present Grand isolated at this time as he found himself being an ing in springs from the base of the Grand Wash Canyon, and debouched into closed basins west “old river” advocate in an increasingly “young Cliffs. This view also did not gain wide accep- of the plateau. However, if such a stream had river” environment. His paper was an attempt tance within the Grand Canyon community of any considerable length, it should have contrib- to restore luster once again to the earlier ideas geologists, and Hunt is often remembered more uted rounded pebbles representing the varied of Powell and Dutton, and he offered intriguing for his signifi cant contributions regarding the lithology east of the Grand Wash Cliffs. No such and novel ideas on the origin of the river and evolution of upper Colorado River basin and the stream-worn pebbles have been found in the Grand Canyon. central Colorado Plateau. basin deposits” (Longwell, 1946, p. 823). Hunt agreed that as the plateau became Longwell was describing what would later elevated higher with respect to the Basin The 1964 Symposium and a Poly-Phase become known as the “Muddy Creek prob- and Range, drainage had to develop off of History for the River—Edwin D. McKee lem” or the “Muddy Creek constraint.” This the plateau edge, but he was constrained by et al. idea, as initially presented, stated that the the Muddy Creek evidence. This led him to Colorado River could not have existed in its propose that the Colorado River might have By the 1960s, a solution was needed to present position or confi guration prior to the exited the western part of Grand Canyon to the address the confl icting evidence for a “young” emplacement of the Fortifi cation Hill basalt south through Peach Springs Wash. A decade versus “old” Colorado River. Edwin (Eddie) near Hoover Dam (which capped Muddy later this became untenable as the deposits in McKee, a preeminent Grand Canyon geologist, Creek sediments at that location). Sometime Peach Springs Wash showed north-directed convened a special symposium at the Museum later, the evidence was more specifi cally con- fl ow toward the Hurricane fault zone (Young, of Northern Arizona (MNA) in August 1964. strained to the Hualapai Limestone Member of 1966). Hunt was then left with two possibilities For the fi rst time in history, scientists gathered in the Muddy Creek Formation near the Grand for the origin of the river in Grand Canyon— a single location to specifi cally discuss problems Wash Cliffs, where an ash bed is radiometri- superposition or —and he didn’t associated with the processes that may have cally dated at 5.97 Ma (Spencer et al., 1998). like either of them. Superposition demanded formed the Colorado River and Grand Canyon, This is the evidence used for the widely cited that lake sediments be present as high as the and their age. Twenty geologists attended the age of <6 Ma for the Grand Canyon. top of the Kaibab Plateau at 2750 m and even ten-day symposium to share ideas and propos- In just a little over a single decade, both higher toward the north. This seemed unrea- als to address specifi c dilemmas. Charlie Hunt Blackwelder and Longwell provided critical sonable to him. Stream capture was also prob- was curiously absent from the list of attendees, support for a “young” Colorado River. Lon- lematic because: “It would indeed have been a refl ecting a professional rivalry that had likely gwell summarized these fi ndings at the close of unique and precocious that cut headward developed between him and McKee. McKee his paper: “In outlining the foregoing hypoth- more than 100 miles across the Grand Canyon had already enlisted the help of two doctoral esis, it has been assumed that the Plateau has section to capture streams east of the Kaibab students to look at critical deposits and geologic had exterior drainage continuously though the upwarp” (Hunt, 1956, p. 85). relationships in the western Grand Canyon. This Cenozoic era. However, as Blackwelder sug- Hunt ultimately invented a process to action may have been done in part to verify or gests, the region probably was unable to support address the dilemma, calling it anteposition, refute some of the claims by Hunt, which ran a through-fl owing stream like the Colorado for which incorporates aspects of antecedence and contrary to those of McKee (see the next two a considerable period after the onset of aridity superposition. Anteposition proposed that the sections regarding the work by Ivo Lucchitta . . . During such an interval the drainage of the path of the Colorado River through and Richard Young). Plateau area would have been accomplished by Grand Canyon was established before Muddy Two signifi cant results came out of this piv- intermittent streams ending in a number of sep- Creek time (the antecedent part). Uplift of the otal symposium that shaped thinking for the arate closed depressions, as in the Great Basin plateau edge then tilted the river’s channel remainder of the century: the development of at present . . . When the Cordilleran region toward the east, disrupting and halting the fl ow a timeline outlining a plausible sequence of attained such altitude that increased precipita- of water into the Grand Wash trough, which landscape-forming events; and an original and tion in the Rocky Mountains supplied a surplus for him solved the Muddy Creek problem. He provocative theory regarding how the Colo- of runoff into the Plateau, the confi guration of further postulated that the river was ponded rado River (and by extension Grand Canyon) the surface may have been such as to guide the north and east of Grand Canyon and as this formed from the integration of two separate overfl ow along a new consequent course to the lake became fi lled at a later time, it overfl owed and distinct river systems (Fig. 5). In the fi nal west” (Longwell, 1946, p. 833). to the south and west. The Colorado River bulletin, the authors outlined a fi ve-stage evo- then re-established its old course on the lake lutionary history of the landscape: (1) initial INTEGRATING THE COLORADO sediments and in the previously carved canyon northeast drainage across a subdued, low-lying RIVER—MID-TWENTIETH CENTURY (superposition) making its way to the Grand surface near sea level; (2) Laramide uplift of the Wash Cliffs and initiating the of the plateau surface with continued northeast drain- Reviving an Old Colorado River— Hualapai Limestone. age around monoclinal upwarps and toward Charlie Hunt Hunt offered additional ideas in a U.S. Geo- freshwater lakes in the northern plateau; (3) the logical Survey Professional Paper commemo- development of two separate and distinct drain- Charlie Hunt of the U.S. Geological Survey rating the 100th anniversary of the Powell age systems, each on either side of the Kaibab wrote a classic paper in southwestern geology Expedition (Hunt, 1969). In this paper he pro- upwarp with the younger, steeper, west-directed

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Hualapai drainage headed toward the Gulf of and Bidahochi basins, respectively; and (5) the , and intersected and captured California, and the older, more sluggish ances- integration of the two drainages by renewed the ancestral upper Colorado River. The point tral upper Colorado River fl owing southeast uplift, headward erosion, and stream capture of capture was hypothesized to have occurred along the present course of the Little Colorado (McKee et al., 1967). at the present-day confl uence of the Colorado River and possibly into the system; McKee et al. (1967) proposed that the and Little Colorado rivers, but within higher (4) the initiation of interior basins to the west steep-gradient Hualapai drainage lengthened Triassic-age strata now eroded. The ideas and east of Grand Canyon and the Muddy Creek its channel in the upstream direction (east) by generated at this symposium received much exposure, support, and fanfare in the years immediately following the gathering. The symposium introduced new processes to inte- grate the river—headward erosion and stream piracy—providing an innovative hypothesis for the development of the Colorado River and the Grand Canyon. It also helped solve the dilemma for how the river could be Miocene or older in upstream sections, but no older than Pliocene at the Grand Wash Cliffs. Headward erosion, stream piracy, and the integration of the Colorado River from separate ancestors would be the lasting legacy of this important meeting and results from it still bear some infl uence on the thinking on the evolution of the river and the canyon. However, by the mid-1970s, some cracks began to appear in the idea that the upper Colorado River once went to the southeast (Sutton, 1974). He showed that the fl uvial member of the Bidahochi Formation was deposited by southwest-fl owing streams, precluding that the ancestral upper Colorado River fl owed southeast from the area of the Grand Canyon.

LATE TWENTIETH CENTURY

Research at the Grand Wash Cliffs— Ivo Lucchitta

As a result of the 1964 symposium, new ideas concerning a poly-phase development of the river invigorated the fi eld of Grand Canyon studies. Eddie McKee engaged doctoral stu- dents who were conducting research in western Grand Canyon, where critical deposits and fi eld relationships would shed light on the timing and evolution of the river (and perhaps refute the

Figure 5. Diagram showing the sequential development of the Colorado River through Grand Canyon by headward erosion and stream piracy: (A) two separate and dis- tinct drainage systems on either side of the Kaibab upwarp; (B) headward lengthening of the Hualapai drainage, which ultimately captures the ancestral Upper Colorado River drainage; and (C) subsequent deepening of the integrated river to create the modern Grand Canyon (adapted from McKee et al., 1967, and taken from Ranney, 2012, p. 87).

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proposals of Hunt). Ivo Lucchitta conducted The Dilemma of an Immoveable Object— Toward the Twenty-First Century detailed mapping in the Grand Wash trough Earl Lovejoy and Beyond where the Muddy Creek Formation was depos- ited near the mouth of Grand Canyon. Lucchi- Earl Lovejoy, professor at the University of The remaining dilemmas in the aftermath of tta not only verifi ed the conclusions of Chester , El Paso, offered an innovative solution the1964 symposium eventually led to a period Longwell but added fi ner details to them. He to the Muddy Creek constraint (Lovejoy, 1980), of renewed interest in the origin of the Colorado showed, for example, how deposits of non-river derived in part from observations he made along River and Grand Canyon. This began with a alluvium (called the Pearce Canyon fan) ema- the Rio Grande in Big Bend, Texas, and the second symposium at Grand Canyon National nate from a side canyon on the north side of the Truckee River in Nevada. He postulated that Park in June 2000. A volume containing 33 pub- river but are found today on both sides of the the Colorado River could have been in place lished papers from the 73 geologists in atten- river. This prohibited the existence of the Colo- within Grand Canyon during deposition of the dance was the result (Young and Spamer, 2001). rado River in that location during Muddy Creek Muddy Creek Formation, but that it might have Heated debates were again evident between old time. He also affi rmed that the Muddy Creek been defl ected to the south along the base of the canyon advocate Don Elston and young canyon Formation lacked diagnostic pebbles or cobbles Grand Wash Cliffs by the east-directed wedge supporter Ivo Lucchitta. These two essentially from bedrock exposures upstream of the Grand of sediment in the Muddy Creek deposits. Love- fi lled the roles held by Charlie Hunt and Eddie Wash trough. joy had observed a similar setting where the Rio McKee, respectively, from the previous sympo- Lucchitta continued in the latter decades of Grande exited Santa Elena Canyon in the Big sium and showed that after 36 years, the debate the twentieth century to refi ne his ideas and Bend area. He also noted how the Truckee River over the age of the canyon was not yet resolved. became a vocal proponent for a Colorado River in Nevada had dropped its load of coarse sedi- A third conference was held in May 2010 that was no older than latest Miocene (Lucchitta, ment upstream from a narrow canyon and used at the U.S. Geological Survey in Flagstaff, 1972, 1987, 1989). He also proposed late Neo- this as a proxy for why the Muddy Creek For- Arizona. With 59 geologists in attendance, gene uplift of the Colorado Plateau as the driv- mation held no observable clasts from upstream there were numerous papers published in two ing force for the deep dissection of the youthful of the Grand Wash Cliffs. He sought to keep the volumes (Beard et al., 2011; Karlstrom et al., canyon (Lucchitta, 1979), although later work- idea of a Paleogene Colorado River alive and 2012). Again there was debate on the specifi c ers sought to discount the relative importance offered these viable solutions. But in the end, age of the canyon with numerous workers (fore- of recent uplift by showing that the Bouse For- virtually no one noticed. most among them being Karl Karlstrom) giving mation was not entirely marine (Spencer and evidence for a young canyon, while Brian Wer- Patchett, 1997). Lucchitta was perhaps the most A Cretaceous Laramide Grand Canyon— nicke of California Institute of Technology took widely cited researcher concerning Grand Can- Don Elston on the role of old canyon advocate. New analyti- yon’s evolution in the last quarter of the twenti- cal techniques such as thermochronology, detri- eth century. As the twentieth century drew to a close, tal zircon studies, and high-precision Ar dating another attempt to revive ideas for an old Grand were employed and provided a completely new Research on the Hualapai Plateau— Canyon was made by Don Elston, U.S. Geo- approach to solving intractable problems. Richard Young logical Survey geologist. His friend and men- Finally, a two-day Special Session at the tor, Charlie Hunt, had drawn Elston into the 125th Annual Meeting of the Geological Soci- Another doctoral student who took to the Grand Canyon debate. Elston was not deterred ety of America in Denver, Colorado, was held in fi eld during the time of the 1964 symposium by the evidence from the Muddy Creek Forma- October 2013, with more innovative ideas pre- was Richard Young, who studied gravel depos- tion and introduced distinctive ideas for how the sented on the origin of the canyon and the river. its on the Hualapai Plateau in western Grand Colorado River could be quite old (Elston and The Grand Canyon continues to attract, edu- Canyon (Young, 1966). Young’s work pro- Young, 1991). Claiming that canyon incision cate, and inspire a host of modern geologists, vided supporting evidence for an initial north- began at the beginning of the Late Cretaceous who stand on the shoulders of their heroic pre- east drainage across the southern Colorado (ca. 100 Ma), Elston argued that the majority decessors. It was these pioneering geologists Plateau after withdrawal of the Western Inte- of canyon incision occurred no later than the who announced to the world that the Grand rior Seaway. In Milkweed and Hindu canyons, Paleogene, invoking a hyper-arid period during Canyon was a truly special place and not merely Young found clasts that were derived from the Miocene in which in the Colorado a profi tless locality. the south and contained paleocurrent indica- River became greatly diminished and Grand ACKNOWLEDGMENTS tors with fl ow toward the north. This disclosed Canyon became buried in up to 240 m of side a source area for the gravel in the Mogollon canyon sediment. To him this could explain the I would like to acknowledge one anonymous Highlands, formerly located southwest of lack of diagnostic pebble clasts in the Muddy reviewer, who provided helpful suggestions to the origi- nal manuscript. Thanks to Karl Karlstrom, University Grand Canyon. The deposits were found in Creek Formation. His ideas were not widely of New , who encouraged me to contribute this paleocanyons 1200 m deep, which inferred accepted, but he remained a forceful voice in article to the Geosphere volume on Grand Canyon and signifi cant uplift and dissection at a relatively Grand Canyon origin studies, keeping the “old” served as a helpful and constructive guest reviewer. Ivo early age in the area of western Grand Canyon. river concept alive in the latter parts of the twen- Lucchitta and Dick Young provided information on the Although the deposits disappear to the north, tieth century. 1964 Symposium and the possible confl ict that existed between Eddie McKee and Charlie Hunt. As always, I Young later postulated that they perhaps were The century came to an end with geologists would not be able to remain involved in the fascinating routed along the trace of the Hurricane fault having resolved some of the earliest issues story of the Grand Canyon were it not for the profes- (Young, 2001). Along with Lucchitta, Young associated with Grand Canyon’s origin but no sional geologists who continue to conduct geologic was a prolifi c publisher of data as it concerned consensus on the specifi c timing, processes, or research in the Grand Canyon. Particular thanks to Ivo Lucchitta (U.S. Geological Survey, retired) who inspired the area of western Grand Canyon in the latter incision rates that led to the integration of the in me an initial attraction for the mysteries surrounding parts of the twentieth century. Colorado River system. the origin of the Colorado River in Grand Canyon.

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