How a New Geology and Glacial Paradigm Explains Colorado South Platte-Arkansas River Drainage Divide Topographic Map Evidence, USA

United States Geological Survey (USGS) topographic maps (available at the USGS National Map website) are used to determine development of the asymmetric South Platte River drainage basin (south of Denver) by noting low points (referred to as divide crossings) where south-oriented floodwater channels once crossed the South Platte-Arkansas River drainage divide. Twelve groups of observed divide crossings are described most of which show evidence for flood-formed diverging and converging channels including where divide crossings are cut across Thirtynine Mile volcanic field ejectamenta. A new Cenozoic geologic and glacial history paradigm requires southeast- and south-oriented floods to have flowed across what is now the east-west continental divide to reach the southeast-oriented Arkansas River valley and to have eroded the divide crossings before north-oriented South Platte River valley headward erosion captured the flow. Such floods are not consistent with accepted Cenozoic geologic and glacial history interpretations, but are consistent with new paradigm interpretations (developed to explain Missouri River drainage basin topographic map drainage system evidence) in which a thick continental ice sheet (located where large continental ice sheets are usually reported to have been) deeply eroded the underlying bedrock and caused crustal uplift to create a deep “hole” with a deep “hole” rim segment roughly following today’s Wyoming and northern Colorado east-west continental divide and then continuing eastward along what is now the Mis-souri-Arkansas River drainage divide. The new paradigm results in a Cenozoic geologic and glacial history in which immense south-oriented continental ice sheet meltwater floods first flowed in a south direction across the rising deep “hole” rim and were then forced by rim uplift to flow along the rim subsequently in north directions into the developing deep “hole”.


Statement of the Research Problem
To a geomorphologist the South Platte River drainage system south of Denver (see Figure 1 and The geologic research community's failure to say much about South Platte River drainage system history is intriguing because published reports say much more about the regional geologic structures, stratigraphy, volcanic activity, economic resources, and paleontology than they say about the regional drainage history. For example, two recent Colorado Geological Survey reports [1] [2] describe Park County geology but hardly mention the regional drainage history even though significant regional South Platte River drainage history events must have occurred. This failure to determine regional drainage histories is not unique to the South Platte River headwaters region and shows up in geologic literature pertaining to most other drainage systems. While geologists rarely say so, they are reluctant to determine regional drainage histories because the drainage histories determined from detailed topographic maps (on which drainage history evidence is most easily observed) frequently do not agree with commonly accepted Cenozoic geology and glacial history paradigm (accepted paradigm) interpretations.
According to Thomas Kuhn [3] the geology research community has consciously and/or unconsciously determined (usually without saying so) that most   Open Journal of Geology been applied for many decades and is unfortunate because USGS detailed topographic maps provide much of the information needed to easily reconstruct former drainage routes and having a knowledge of prior drainage routes is critical if geologists want to correctly understand a region's Cenozoic geologic and glacial history. The author of this paper [4] recently used Missouri River drainage basin topographic map evidence to construct a paradigm (new paradigm) able to explain topographic map drainage system and erosional landform features. This new paradigm explains most Missouri River drainage basin topographic map drainage system and erosional landform evidence by requiring a thick North American continental ice sheet (located where large continental ice sheets are usually thought to have been) that deeply eroded the underlying bedrock (accepted paradigm ice sheets did not deeply erode the underlying bedrock) and that weighed enough to raise surrounding regions to create a deep "hole" in which the thick ice sheet was located and in which a much thinner ice sheet later formed (accepted paradigm ice sheets did not cause surrounding region uplift or create a deep "hole"). The new paradigm's deep "hole" southwest rim rose as massive south-oriented meltwater floods flowed across it and was located along what is today the Montana, Wyoming, and northern Colorado east-west continental divide and then continued eastward roughly following today's Missouri River-Arkansas River drainage divide. Present day drainage patterns evolved as valleys eroded headward to capture the massive meltwater floods and as mountain and regional uplift forced floodwaters to flow along the deep "hole" rim and subsequently into deep "hole" space being opened up as the large ice sheet melted. The completely different and incompatible accepted and new paradigms lead to incompatible Cenozoic geologic and glacial histories. This paper describes how the new paradigm explains some of the yet to be explained South Platte River headwaters region topographic map drainage system and erosional landform evidence.

Geographic Setting
The South Platte River headwaters drainage basin (south of Denver) is located in central Colorado and is bounded on the northwest by mountains forming the North American east-west continental divide (with the southwest-oriented Colorado River headwaters drainage basin on the other side and the north-oriented North Platte River headwaters drainage basin to the north of the Colorado River headwaters drainage basin), on the west and southwest by the Mosquito Range (which forms a segment of the South Platte River-Arkansas River drainage divide), on the south and southeast by the Thirtynine Mile volcanic field including the largely eroded Guffey volcano and other hills (which are also located along the South Platte River-Arkansas River drainage divide), and on the east and north by the Rampart Range (including Pikes Peak) and the Front Range. Much of the South Platte River headwaters drainage basin is located in South Park, which when compared with surrounding mountains is a relatively flat inter- Fenneman ([6]: p. 103-104) describes South Park as a peneplain surface about 80 kilometers in diameter at an altitude ranging from less 2743 to more than 3048 meters which "extends in some areas eastward with increasing dissection from the Park to the foothills. On the south there is no sharp limit short of the Arkansas River". Thornbury ([7]: p. 343) comments "Actually much of the Park does have low relief, but there is diversity of topography in the form of pediments, stream terraces, lateral and terminal moraines, and outwash plains". The South Platte River is formed in South Park at the confluence of its generally southeast-oriented South Fork and Middle Fork (both of which begin in the surrounding mountains) and then flows in a southeast direction before turning in a northeast direction to leave South Park proper and flow through Elevenmile Canyon before turning in a north direction to cross the Front Range, although southeast-oriented Tarryall Creek, which also begins along the east-west continental divide flows through northern South Park before reaching the north-oriented South Platte River. Further north the North Fork (South Platte River) begins at the continental divide and flows in southeast, east, and northeast directions through mountainous regions before joining the north-oriented South Platte River.

Previous Work-Accepted Paradigm Interpretations
River canyons crossing Rocky Mountain ranges and evidence for high-level Rocky Mountain erosion surfaces intrigued early geomorphologists who lacked the good quality topographic maps available today. High-elevation peneplains (or erosion and deposition surfaces) were proposed to have extended across the Colorado Front Range area on which today's drainage systems formed (although details of drainage system formation were rarely given). Regional uplift enabled what were proposed to be superimposed drainage systems to cut into the underlying mountains and to remove basin fills that had partially buried mountain ranges and to excavate or partially excavate intermontane basins. For example, Atwood ([8]: p. 315) comments "Late in Tertiary time, after the mountain ranges had been subdued, after thousands of feet [meters] of mid-Tertiary sediments had accumulated, after the great volcanic flows of Colorado… had poured forth, after the vast quantities of ejectamenta had settled and accumulated as breccias, tuffs, and ash beds, and just before the opening of the Pleistocene period" the entire Rocky Mountain region was uplifted and streams that had been flowing over buried mountain ranges lowered their channels so as to produce the gorges and water gaps seen today. This superposition hypothesis has been rarely challenged, although Pelletier ([9]: p. 5) cites several researchers who suggest middle "Cenozoic peak elevations were as high or higher than today" and proposes climate change as an alternate explanation for the southern Rocky Mountain re- Determining details of the South Platte River headwaters drainage development does not appear to have been a previous research priority, although some investigators saw evidence for a south-oriented drainage system flowing to the Arkansas River prior to the present-day north-oriented South Platte River canyon. Stark et al. ([5]: p. 141) for example, based on previously mentioned southoriented South Park regional slopes suggested southeast-oriented South Platte River headwaters once flowed to the Arkansas River and were shifted (by volcanic activity and possible regional uplift) to flow in an "east" direction [they probably meant in a "north" direction]. Thornbury,([7]: p. 344) attributes the South Park drainage diversion to regional uplift and tilting. Epis and Chapin ([10]: Figure 9, p. 58) identify on plastic relief maps (U.S. Army Map Service 2˚ quadrangles) south-oriented paleovalleys leading from the South Platte River headwaters area to the Arkansas River and discuss regional deformation, but like Stark et al. and Thornbury do not describe the capture events required to shift south-oriented drainage from the nearby Arkansas River northward to the more distant Platte and Missouri Rivers.
The Guffey volcano and associated Thirtynine Mile Mountain volcanic materials are sometimes described as having formed on a late Eocene erosion surface (or peneplain) and are located along what is now the South Platte River-Arkansas River drainage divide. Epis and Chapin ([10]: p. 57) indicate the Guffey volcano flanks "are well preserved in an elliptical ring of mountains composed of outward-dipping andesitic flows and breccias. The steepest dips are to the north (10˚ to 15˚) on Thirtynine Mountain and to the west (8˚) on Black Mountain. To the east… the flows have dips of only 2˚ to 6˚. The gentlest dips are to the southeast where andesitic lavas flowed at least 11 km down a paleovalley." The cover of McGookey's book [11] shows a large stratovolcano rising above this ring although not all previous investigators agree with his interpretation. Detailed 1:62,500 scale geologic maps by Wobus and Epis [12] and Epis et al. [13] document extrusive igneous rocks, mudflows, and related materials covering the area where the Guffey stratovolcano supposedly stood. Today deep north-to-south oriented through valleys crossing the South Platte River-Arkansas River drainage divide are eroded on either side of the east-to-west oriented Thirtynine Mile Mountain. If a high stratovolcano formed in Oligocene time as sometimes proposed subsequent volcanic activity and/or water erosion has almost completely removed that large mountain.
McGookey ([11]: p. 143) attributes diversion of South Park drainage to the north-oriented South Platte River to Guffey volcano related mudflows which "dammed the pre-Oligocene south-flowing drainage and caused a large lake to develop over South Park and in the Florissant Valley. The outlet from the South Park Lake became the South Platte River, which is superimposed across the Front Range". Earlier he commented (p. 33) "Just why the river cut a straight northeast trending canyon has not been explained. There is no obvious line of weakness". Meyer et al. ( 15) states "It is reasonable to conclude, therefore, that the original areal extent of the lake paleobasin is unknown; and that, as a result, much information about the original topography and the nature of the catchment area is unknown". Efforts to explain South Platte River headwaters drainage system history in a manner consistent with accepted paradigm Cenozoic geologic and glacial histories have produced general hypotheses in which volcanic and/or tectonic activity blocked an earlier south-oriented drainage system to create the north-oriented South Platte River drainage system, but most details are left to the reader's imagination. Previous researchers do not report using topographic map evidence to conduct simple tests such as studying low points (or divide crossings) along the South Platte River-Arkansas River drainage divide to determine how blockage of earlier south-oriented drainage routes explains the map evidence. As this paper describes low points (or divide crossings) along the South Platte River-Arkansas River drainage divide indicate multiple streams of south-oriented water (some flowing in complexes of diverging and converging channels) eroded the volcanic and mudflow deposits claimed by some previous researchers to have blocked the south-oriented drainage routes. While evidence for at least some blockage and lake formation is good the topographic maps show evidence for large south-oriented flood flows that occurred after the blockages and makes it difficult to explain how the north-oriented South Platte River canyon developed. The topographic map evidence indicates the rather vague accepted paradigm hypotheses leave out many important details.

Previous Work-New Paradigm Interpretations
The new paradigm explains Missouri River drainage basin topographic map create what are today the north-northwest oriented Blue River drainage system and the Colorado River-South Platte River drainage divide". Another new paradigm demonstration paper [17] describes how topographic map evidence shows how mountain uplift blocked south-oriented floodwaters that were moving from the now north-oriented North Platte River headwaters area into the Colorado River valley and forced the floodwaters to make a U-turn so as to flow in a north direction into the Laramie Basin and then across the rising Laramie Range as described in an earlier new paradigm demonstration paper [18] to reach what was at that time an actively eroding southeast-oriented North Platte River valley. Still another new paradigm demonstration paper [19] describes how headward erosion of that southeast-oriented North Platte River valley (along the northern Laramie Mountains northeast margin) beheaded and reversed south-oriented floodwaters flowing into the Laramie Basin and next beheaded and reversed flood flow moving south from the Casper, Wyoming area into north central Colorado to create the north-, east-, and southeast-oriented North Platte River route seen in Figure 1. Topographic map evidence is also used in two other new paradigm demonstration papers [20] [21] to show how a northeast-oriented South Platte River valley segment eroded headward across massive south-oriented floods from the western Nebraska North Platte-South Platte River confluence area into northeast Colorado. In summary, published new paradigm demonstration papers have interpreted detailed topographic map drainage system and erosional landform evidence to reconstruct how much of the previously unexplained North Platte and South Platte River drainage systems developed.
Not yet documented in published new paradigm demonstration papers is a test of the new paradigm prediction that deep "hole" rim area uplift enabled east-and northeast-oriented South Platte River valley headward erosion (north of Denver) to behead and reverse south-oriented floodwaters which had been moving across a rising Front Range (south of Denver) to join southeast-oriented floodwaters flowing across what is now the Colorado River (headwaters area)-South Platte River (headwaters area) drainage divide (now the east-west continental divide) and then to continue flowing in a south direction to what must have been an actively eroding Arkansas River valley. Prior to Arkansas River valley headward erosion the new paradigm predicts those floodwaters flowed to what are now the Rio Grande River and Pecos River drainage basins and in northeast New Mexico that headward erosion of the Canadian River valley captured some of the south-oriented flood flow (predictions which can be tested by observing detailed topographic map drainage system and erosional landform

Research Method
This study began by using detailed topographic maps available at the USGS Na-

Results
Weston Pass in the Mosquito Range (DC-1 in Table 1 and in Figure 2 Trout Creek Pass, which Stark et al. [5] show may follow a fault line appears to have been eroded in sedimentary strata by a large and prolonged stream of water that must have flowed from what is now the south-oriented South Fork South Platte River alignment (upstream from Antero Reservoir) across Trout Creek Pass to reach south-southeast oriented water on the Trout Creek headwaters alignment and which was subsequently captured by headward erosion of the southwest-oriented Trout Creek valley. South-oriented flow across Trout Pass was subsequently beheaded and reversed to create north-oriented Salt Creek drainage by South Fork South Platte River valley headward erosion (which also involved beheading and reversal of a different south-oriented flood flow channel to create a north-oriented South Fork South Platte River segment between Antero Reservoir and Hartsel). The southwest-oriented Mushroom Gulch water gap across Kaufman Ridge suggests the south-oriented stream diverged to the east of Trout Creek Pass with some water flowing in a south-southeast direction along the Kaufman Ridge east flank before turning in southwest direction to erode the Mushroom Gulch water gap and then to join Trout Creek while a diverging stream of water flowed across Trout Creek Pass to join the south-southeast oriented Trout Creek alignment west of Kaufman Ridge and to converge with the Mushroom Gulch water gap stream of water just south of the Trout Creek Limestone Ridge water gap.     The drainage pattern seen in Figure 6 is difficult to explain from an accepted paradigm perspective, but much easier to explain when viewed from the new paradigm perspective. For example, note how there are as many south-oriented drainage routes as there are north-oriented drainage routes. DC-15 in Figure 6 identifies a north-to-south oriented divide crossing which links south-oriented Pine Creek with the north-northeast-oriented South Platte River. Headward ero-

Discussion
With the exception of DC-1, DC-13, DC-14 and DC-15 all of the described divide crossings suggest large floods of south-oriented water flowed from the northoriented South Platte River drainage basin into the southeast-and east-oriented Arkansas River drainage basin while DC-13, DC-14 and DC-15 suggest the now north-oriented South Platte River valley originated as a south-oriented flood flow channel. Further, many divide crossings are eroded across areas directly or indirectly affected by Thirtynine Mile volcanic activity and are younger than the volcanic affected materials. Previous (accepted paradigm) investigators such as Epis and Chapin (1975) suggested the Thirtynine Mile volcanic activity occurred on top of a southward sloping late Eocene peneplain surface and identified paleovalleys cut in that surface. If those paleovalleys predate Thirtynine Mile volcanic activity and the divide crossings described here postdate the volcanic activity the Thirtynine Mile volcanic activity may have occurred as massive south-oriented floods flowed across the region and may be indirectly related to the flood source. Likewise, the flow reversal in the now north-oriented South Platte River valley enabled a deeper north-oriented valley to erode headward (in a south direction) along what had been south-oriented flood flow channels. To explain the South Platte River flow reversal tectonic uplift must have raised the South Platte River headwaters region relative to regions further to the north and the tectonic activity must have occurred as the southeast-and south-oriented floods flowed across the region. Such a scenario is inconsistent with accepted paradigm interpretations, but is what the new paradigm predicts. The South Platte River headwaters area is located along a segment of the new paradigm's deep "hole" rim which was being raised by continental ice sheet caused crustal uplift as massive Open Journal of Geology south-oriented meltwater floods first flowed across it and were subsequently diverted by the rim uplift to flow along the rim and eventually to flow toward the deep "hole." As deep "hole" rim uplift progressed the south-oriented Mississippi River became the only deep "hole" southern outlet and at first valleys such as the Arkansas River valley eroded headward in a westward direction from that outlet to divert south-oriented floodwaters toward that outlet. But as deep "hole" rim uplift and headward erosion of the Mississippi River valley outlet progressed the Missouri River valley eroded headward to not only divert south-oriented floodwaters toward the Mississippi River outlet but also to capture south-oriented floodwaters from further to west which the deep "hole" rim uplift was diverting in north directions and into the developing deep "hole". Many southeast-oriented South Platte River headwaters and tributaries now begin in formerly glaciated mountain regions located along the east-west continental divide which means the massive south-oriented meltwater floods must have flowed across what is now the southwest-oriented Colorado River headwaters drainage basin (as described in a previously cited new paradigm demonstration paper [16]). Headward erosion of the deep southwest-oriented Colorado River valley into what must have been a rising deep "hole" rim region progressively captured (from west to east) south-and southeast-oriented floodwaters moving toward the South Platte River headwaters area. This new paradigm interpretation implies that as deep "hole" rim uplift began large south-oriented meltwater floods also entered the Colorado River drainage basin. New paradigm demonstration papers not previously cited show south-oriented meltwater floods also flowed across what is now the Wyoming Great Divide Basin into the Colorado River drainage basin [23] [24] and within the Colorado River drainage basin across what is now the Yampa River-Colorado River drainage divide to reach the Colorado River valley [25]. While not the subject of this paper these new paradigm demonstration papers document immense volumes of meltwater which must have entered the Colorado River drainage basin and which were probably responsible for many Colorado River drainage basin erosional features. More pertinent to this paper's geographic area the evidence presented here documents how headward erosion of a deeper north-oriented South Platte River valley along what had been south-oriented flood flow channels (in the region south of Denver) captured south-and southeast-oriented flood flow, which had been moving to the Arkansas River valley and which Colorado River valley headward erosion subsequently captured.
The new paradigm interprets the mountain glaciation to have occurred after

Conclusions
Previous ing south-oriented Mississippi River valley and finally were forced to flow in north and northeast directions toward deep "hole" space located between the rising deep "hole" rim and the melting ice sheet.