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CRevolution 2: Origin and Evolution of the Colorado River System II themed issue Implications of the Miocene(?) Crooked Ridge River of northern Arizona for the evolution of the Colorado River and Grand Canyon Ivo Lucchitta1,*, Richard F. Holm2, and Baerbel K. Lucchitta3 1U.S. Geological Survey, Flagstaff, Arizona 86001, USA, and Museum of Northern Arizona, Flagstaff, Arizona 86001, USA 2Northern Arizona University, Flagstaff, Arizona 86011, USA 3U.S. Geological Survey, Flagstaff, Arizona 86001, USA ABSTRACT epic journey of discovery on the Green and Col- river fl owed southward through Peach Springs orado Rivers. The debate has illuminated not Canyon (Fig. 1) until late Miocene time, when it The southwesterly course of the probably only the history of the Colorado River itself, but established its present course in western Grand pre–early Miocene and possibly Oligocene of rivers and canyons in general. Of especial sci- Canyon by some subterranean piping mecha- Crooked Ridge River can be traced continu- entifi c and popular interest is the question: How nism. The problem was not solved, however, ously for 48 km and discontinuously for 91 did this canyon, the Grand, come to be? because the widespread interior-basin deposits km in northern Arizona (United States). Views on the issue are in two main groups: would have blocked this course as well. Such The course is visible today in inverted relief. One holds that the river is old (possibly as old deposits are ubiquitous in the Basin and Range Pebbles in the river gravel came from at least as Eocene) and has always had approximately province, not just along the lower Colorado as far northeast as the San Juan Mountains its present confi guration; the other holds that River area. Furthermore, Young’s (1979, 1982) (Colorado). The river valley was carved out the river has achieved its present course only work showed that fl uvial deposits in Peach of easily eroded Jurassic and Cretaceous relatively recently (generally near the end of Springs Canyon were deposited by streams rocks whose debris overloaded the river with the Miocene) through one of several processes fl owing north, not south as proposed by Hunt. abundant detritus, probably steepening the of integration, including headward erosion and The stage was set for the notion that an ancient gradient. After the river became inactive, the stream capture, lake spillover, subterranean pip- upper river and a much younger lower one were regional drainage network was rearranged ing, and reactivation of pre-existing canyons, integrated after 5–6 Ma into a single river with three times, and the nearby Four Corners possibly of early Tertiary age. the present course. This idea was strongly infl u- region was lowered 1–2 km by erosion. The Most of the early workers from Powell on enced by the then-new discovery that the upper river provides constraints on the early evolu- (Powell, 1875; Dutton, 1882; Davis, 1901) Gulf of California, into which the Colorado tion of the Colorado River and Grand Can- were proponents of the fi rst notion, as was Hunt fl ows, had opened only in late Miocene to early yon. Continuation of this river into lakes in (1956, 1969), who painstakingly assembled a Pliocene time (Durham and Allison, 1960). Arizona or Utah is unlikely, as is integration host of information about ancient courses of the McKee et al. (1967) argued that the old upper through Grand Canyon by lake spillover. Colorado and San Juan Rivers on the Colorado river reached the east side of the Kaibab Plateau The downstream course of the river prob- Plateau. More recent work generally is part of (Fig. 1), which was seen as an insurmountable ably was across the Kaibab arch in a valley the second group. barrier, and then fl owed southeast along the roughly coincident with the present eastern Studies in the early to mid-1900s in the Basin present alignment of the Little Colorado River Grand Canyon. Beyond this point, the course and Range province along the present course of into the Rio Grande. In latest Miocene time this may have continued to the drainage basin of the lower Colorado River (Lee, 1908; Black- ancestral river was captured east of the Kai- the Sacramento River, or to the proto–Snake welder, 1934; Longwell, 1936, 1946) brought bab Plateau and diverted into its present course River drainage. Crooked Ridge River was about the transition from earlier views to the through Grand Canyon by a vigorous young beheaded by the developing San Juan River, later ones. These studies showed that areas now stream that propagated itself from the Gulf of which pirated its waters and probably was traversed by the Colorado are fi lled with middle California by headward erosion. However, the tributary to a proto–Colorado River, fl owing and late Miocene interior-basin deposits. This course into the Rio Grande was not supported by roughly along its present course west of the was later confi rmed in detail for the Pierce Ferry available data, so Lucchitta (1975, 1984, 1989, Monument upwarp. area at the mouth of Grand Canyon (Fig. 1) by 2013), making use of improved understanding Lucchitta (1966, 1967, 1972, 2013). The con- of the paleogeology and paleotopography of the INTRODUCTION clusion was that no Colorado River could have region, proposed instead that the ancient river existed in its present Basin and Range course had crossed the Kaibab Plateau in an arcuate Debate on how and when the Colorado River until after 5–6 Ma. strike valley controlled by the south-plunging and Grand Canyon (southwestern United States) The question then arose: What was the course part of the Kaibab dome. This valley followed the came into being as we know them today has of the mid-Miocene or earlier Colorado River present alignment of eastern Grand Canyon (see continued in the 140 years since J.W. Powell’s on the western Colorado Plateau for the 10+ Babenroth and Strahler, 1945), then continued million years when it did not fl ow into the Gulf northwest along regional strike, bypassing west- *Corresponding author: [email protected]. of California? Hunt (1969) suggested that the ern Grand Canyon and the lower Colorado River Geosphere; December 2013; v. 9; no. 6; p. 1417–1433; doi:10.1130/GES00861.1; 14 fi gures; 3 tables. Received 14 August 2012 ♦ Revision received 14 August 2013 ♦ Accepted 28 August 2013 ♦ Published online 11 October 2013 For permission to copy, contact [email protected] 1417 © 2013 Geological Society of America Downloaded from http://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/9/6/1417/3343539/1417.pdf by guest on 27 September 2021 Lucchitta et al. Colorado River Uncompahgre Plateau Henry Mtns. La Sal Mtns. Needle Mtns San Juan Colorado River Abajo Mtns. Mtns. Marble Kaibab Plateau Canyon San Juan River Ute Mtns. Pierce Kaibito White Mesa Ferry Plateau Carrizo Mtns. Western /arch Grand Canyon Black Mesa Crooked Ridge Eastern Little Colorado Grand Canyon River Hopi Buttes (area of "Hopi Lake") Hualapai Peach Springs Plateau Canyon Figure 1. Regional view of southwestern Colorado Plateau from the San Juan Mountains to the western Plateau edge near Pierce Ferry. Base map extracted from 10 m-resolution U.S. Geological Survey (USGS) National Elevation Dataset by J. Luke Blair, USGS. Labels by authors. Note: bar scale is accurate. area. Subsequent capture and diversion by the history of the Colorado River and its integration in directions (generally north or northeast) other younger stream would have been as per McKee into the present course through Grand Canyon. than the present one (e.g., Scarborough, 2001; et al. (1967), but west of the Kaibab Plateau. Some have ignored the evidence for Muddy Potochnik, 2001; Hill and Ranney, 2008). These proposals contain two major novel- Creek (Miocene) interior-basin deposition at Three current concepts are of particular inter- ties: One is that the Colorado River in its pres- the mouth of Grand Canyon (e.g., Robert et al., est in the context of the present paper. The fi rst ent course through Grand Canyon is no older 2011), or have discounted it (Wernicke, 2011; is that an ancestral upper Colorado River emp- than 5–6 Ma; the other is that river systems are Flowers and Farley, 2012); others proposed that tied into “Hopi Lake” (in which was deposited not immutable, but are part of drainage net- this was never a constraint because some sort of the Pliocene and Miocene Bidahochi Forma- works that change with time through a quasi- canyon already existed in Muddy Creek time or tion) (Fig. 1) during the interval when the river Darwinian competition in response to exter- even earlier (Faulds et al., 2001; Wallace et al., did not fl ow in its present lower course west of nal circumstances such as tectonism and by 2005; Young, 2008; Wernicke, 2011; Flowers the Colorado Plateau. The second is that “Lake means such as headward erosion and capture. and Farley, 2012). Subterranean piping is a pop- Hopi” at one time drained northward along the Drainages with the steepest gradient survive ular theory (Hill et al., 2008; Pederson, 2008), as present alignment of Marble and perhaps Glen and expand their drainage area by capturing is lake spillover (Blackwelder, 1934; Meek and Canyons. The third is that the Colorado River the water of lower-gradient and therefore less Douglass, 2001; Scarborough, 2001; Spencer became integrated in its course through Grand aggressive drainages, which become inactive. and Pearthree, 2001). Another idea is that parts of Canyon and Basin and Range reaches by means There is no “beginning” and no “end” to most Grand Canyon are old and were occupied by the of cascading spillovers—Hopi Lake into Huala- rivers, only changes in the connections and Colorado River but were choked by debris dur- pai Lake (Pierce Ferry area; Fig.

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