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Richard F. Madole

Publications and source records attributed to Richard F. Madole.

16 recordsLinked to original sources
USGS2017

Constraints on the age of the Great Sand Dunes, Colorado, from subsurface stratigraphy and OSL dates

The age of the Great Sand Dunes has been debated for nearly 150 yr. Seven ages ranging from Miocene to late Holocene have been proposed for them. This paper presents new information—chiefly subsurface stratigraphic data, OSL dates, and geomorphic evidence—that indicates that the Great Sand Dunes began to form in the latter part of the middle Pleistocene. The dunes overlie a thick wedge of piedmont-slope deposits, which in turn overlies sediment of Lake Alamosa, a paleolake that began to drain about 440 ka. The wedge of piedmont-slope deposits extends westward for at least 23 km and is as much as 60 m thick at a distance of 10 km from the Sangre de Cristo Range. Ostracodes from one well indicate that the eastern shoreline of Lake Alamosa extended to within 4.3 km of where the Great Sand Dunes eventually formed. The time represented by the wedge of piedmont-slope deposits is not known exactly, but the wedge post-dates 440 ka and was in place prior to 130 ka because by then the dunes overlying it were sufficiently close and tall enough to obstruct streams draining from the Sangre de Cristo Range.

Quaternary Research↗
USGS2016

Geologic map of Great Sand Dunes National Park, Colorado

Geologic mapping was begun after a range fire swept the area of what is now the Great Sand Dunes National Park in April 2000. The park spans an area of 437 square kilometers (or about 169 square miles), of which 98 percent is blanketed by sediment of Quaternary age, the Holocene and Pleistocene Epochs; hence, this geologic map of the Great Sand Dunes National Park is essentially a surficial geologic map. These surficial deposits are diverse and include sediment of eolian (windblown), alluvial (stream and sheetwash), palustrine (wetlands and marshes), lacustrine (lake), and mass-wasting (landslides) origin. Sediment of middle and late Holocene age, from about 8,000 years ago to the present, covers about 80 percent of the park. Fluctuations in groundwater level during Holocene time caused wetlands on the nearby lowland that bounds the park on the west to alternately expand and contract. These fluctuations controlled the stability or instability of eolian sand deposits on the downwind (eastern) side of the lowland. When groundwater level rose, playas became lakes, and wet or marshy areas formed in many places. When the water table rose, spring-fed streams filled their channels and valley floors with sediment. Conversely, when groundwater level fell, spring-fed streams incised their valley floors, and lakes, ponds, and marshes dried up and became sources of windblown sand. Discharge in streams draining the west flank of the Sangre de Cristo Range is controlled primarily by snowmelt and flow is perennial until it reaches the mountain front, beyond which streams begin losing water at a high rate as the water soaks into the creek beds. Even streams originating in the larger drainage basins, such as Sand and Medano Creeks, generally do not extend much more than 4 km (about 2.5 miles) beyond where they exit the mountains. The Great Sand Dunes contain the tallest dunes (maximum height about 750 feet, or 230 m) in North America. These dunes cover an area of 72 square kilometers (28 square miles) and contain an estimated 10–13 billion cubic meters (2.4 to 3.1 cubic miles) of sand. The dunes accumulated in an embayment that formed where the trend of the Sangre de Cristo Range changes from southeasterly to southwesterly. They owe their exceptional height to a combination of factors including range-front geometry, topography, an abundant sand supply from the nearby basin, a complex wind regime, and the Sangre de Cristo Range, which prevents continued eastward migration of dune sand deposited by the prevailing southwesterly and westerly winds. Although the sand on the surface of the Great Sand Dunes is of late Holocene age, most of this massive sand body is a complex of deposits that accumulated episodically for more than 130,000 years.

Colorado↗
USGS2012

Holocene alluvial stratigraphy and response to climate change in the Roaring River valley, Front Range, Colorado, USA

Stratigraphic analyses and radiocarbon geochronology of alluvial deposits exposed along the Roaring River, Colorado, lead to three principal conclusions: (1) the opinion that stream channels in the higher parts of the Front Range are relics of the Pleistocene and nonalluvial under the present climate, as argued in a water-rights trial USA v. Colorado, is untenable, (2) beds of clast-supported gravel alternate in vertical succession with beds of fine-grained sediment (sand, mud, and peat) in response to centennial-scale changes in snowmelt-driven peak discharges, and (3) alluvial strata provide information about Holocene climate history that complements the history provided by cirque moraines, periglacial deposits, and paleontological data. Most alluvial strata are of late Holocene age and record, among other things, that: (1) the largest peak flows since the end of the Pleistocene occurred during the late Holocene; (2) the occurrence of a mid- to late Holocene interval (~2450–1630(?) cal yr BP) of warmer climate, which is not clearly identified in palynological records; and (3) the Little Ice Age climate seems to have had little impact on stream channels, except perhaps for minor (~1 m) incision. Published

Colorado↗
USGS2007

Surface-exposure ages of Front Range moraines that may have formed during the Younger Dryas, 8.2 cal ka, and Little Ice Age events

Surface-exposure ( 10 Be) ages have been obtained on boulders from three post-Pinedale end-moraine complexes in the Front Range, Colorado. Boulder rounding appears related to the cirque-to-moraine transport distance at each site with subrounded boulders being typical of the 2-km-long Chicago Lakes Glacier, subangular boulders being typical of the 1-km-long Butler Gulch Glacier, and angular boulders being typical of the few-hundred-m-long Isabelle Glacier. Surface-exposure ages of angular boulders from the Isabelle Glacier moraine, which formed during the Little Ice Age (LIA) according to previous lichenometric dating, indicate cosmogenic inheritance values ranging from 0 to ∼3.0 10 Be ka. 1 Subangular boulders from the Butler Gulch end moraine yielded surface-exposure ages ranging from 5 to 10.2 10 Be ka. We suggest that this moraine was deposited during the 8.2 cal ka event, which has been associated with outburst floods from Lake Agassiz and Lake Ojibway, and that the large age range associated with the Butler Gulch end moraine is caused by cosmogenic shielding of and(or) spalling from boulders that have ages in the younger part of the range and by cosmogenic inheritance in boulders that have ages in the older part of the range. The surface-exposure ages of eight of nine subrounded boulders from the Chicago Lakes area fall within the 13.0–11.7 10 Be ka age range, and appear to have been deposited during the Younger Dryas interval. The general lack of inheritance in the eight samples probably stems from the fact that only a few thousand years intervened between the retreat of the Pinedale glacier and the advance of the Chicago Lakes glacier; in addition, bedrock in the Chicago Lakes cirque area may have remained covered with snow and ice during that interval, thus partially shielding the bedrock from cosmogenic radiation.

Colorado↗
USGS2007

From buttes to bowls: Repeated relief inversion in the landscape of the Colorado Piedmont

Mesas and buttes of the central Colorado Piedmont are composed of at least two distinct rock types, which differ in their cohesiveness and resistance to erosion. The lower parts of the exposed stratigraphic section are poorly cemented, Upper Cretaceous to Middle Eocene sandstones of the Dawson Formation. The caprocks are composed of one or more resistant formations of Late Eocene age: the Castle Rock Conglomerate, Wall Mountain Tuff, and the conglomerate of Larkspur Butte. These formations were originally deposited in topographic lows, but due to their resistance,they now cap prominent buttes and mesas of the Colorado Piedmont. Erosion of the caprock through progressive retreat of the butte scarp produces colluvium that has a higher resistance to erosion than the poorly cemented underlying sandstone. Once the caprock of a butte has been removed by erosion, the underlying weakly cemented Dawson Formation is readily eroded. Ultimately, the armored lower slopes of the former butte remain as a circular ridge standing as much as 100 m above the surrounding topography. This process produces a topographic low surrounded by relict faceted slopes where the flat top of the butte once stood. Prominent alluvial fans are associated with some of these annular features, and they record the main phases of butte removal and excavation of the central part of the armored slopes. Multiple generations of alluvial fans contain coarse- and fine-grained facies that represent changes in effective stream power and record alternating phases of aggradation and erosion. The degree of soil development in the fan alluvium and height of the fan surfaces above streams indicates the oldest preserved gravel fan deposit is of late-middle Pleistocene age. The youngest luminescence (optically stimulated luminescence) dated alluvial fans were deposited during the late Pleistocene about the time of the Pinedale glacial maximum in Colorado, ca. 21,000 yr B.P.

Colorado↗
USGS1995

Spatial and temporal patterns of late Quaternary eolian deposition, eastern Colorado, USA

Eolian sediment covers about 60% of Colorado east of the Rocky Mountains; about 30% of the sediment is sand and 70% is loess. Initially, flood plains were the principal sources of eolian sediment, but during the Holocene, dunes formed from older eolian sand and alluvium on uplands. Since latest Pleistocene time, dominant dune-forming winds have been northwesterly in the northern part of the region and southwesterly in the southern part. At present, sand sheets and dunes, mainly parabolic types, are stable and covered with vegetation. In dunes, sand is commonly 20–30 m thick but elsewhere averages < 10 m. Three sand units are recognized on the basis of bedforms, topographic expression, and soil development. Preliminary age limits for the three units, based on 26 numerical ages, are 22.5–9 ka, 8−1 ka, and l.0−0. 15 ka. The middle unit is the product of multiple episodes of eolian activity that are not yet accurately dated. Loess is widespread but thin (generally < 2.4 m). Three units — middle Pleistocene, late Pleistocene. and Holocene — are recognized on the basis of differences in soil-profile development and stratigraphic position; late Pleistocene loess is by far the most common loess.

Colorado↗
USGS1995

Ribbon Cliff landslide Washington, and the earthquake of 14 December 1872

Estimates of the epicentral location and maximum intensity of the earthquake of 14 December 1872, the largest and oldest historic earthquake documented in the Pacific Northwest, are controversial largely because the estimates are based on ground effects. The Ribbon Cliff landslide is one of the more critical ground effects used to argue that the epicenter was in the vicinity of Lake Chelan in central Washington. Sketchy historical accounts link the Ribbon Cliff landslide to the 1872 earthquake, but a subsequent study disputed the historical accounts and, on the basis of dendrochronology, concluded that the landslide occurred more than 100 yr prior to the earthquake. However, Quaternary stratigraphic relations and the results of multiple dating techniques reported here indicate that the main Ribbon Cliff landslide probably occurred within a 14-yr period that includes the time of the 1872 earthquake. Although our study supports the historical accounts that link the landslide to the December 1872 earthquake, it does not prove that seismic shaking triggered the landslide.

Washington↗
USGS1991

Quaternary history of some southern and central Rocky Mountain basins

This chapter summarizes the current state of late Cenozoic stratigraphic knowledge in some Rocky Mountain basins (here defined as the structurally low portions of major drainage basins) that have been studied in detail since Scott’s (1965) summary on the nonglacial history of the southern and middle Rocky Mountains. The Quaternary history of few of these basins has been studied as intensively as that of the surrounding mountain ranges, despite the wealth of fluvial and other types of deposits present in the basins and the potential for dating them. The areas discussed here include the Bighorn Basin in Wyoming and Montana, the Laramie Basin and part of the Sweetwater River Basin in Wyoming, the Yampa River Basin in Colorado, and the Uinta Basin in Utah (Fig. 1). Small parts of the Great Plains and Colorado Plateau physiographic provinces are included in this discussion. Correlations of deposits within and among some of the areas can now be made more confidently than in 1965 because of detailed mapping and the discovery of many more localities with dated volcanic ashes.

Colorado, Wyoming, Montana↗
USGS1988

Stratigraphic evidence of Holocene faulting in the mid-continent: The Meers fault, southwestern Oklahoma

Stratigraphic relations and ten 14 C ages show that movement occurred on the Meers fault in late Holocene time. Movement on the fault postdates the Browns Creek Alluvium, which began to be deposited between 14,000 and 13,000 yr B.P., and predates the East Cache Alluvium, which was deposited between 800 and 100 yr B.P. Surface warping along the fault led to local stream incision on the upthrown side of the fault and deposition of slopewash and fan alluvium on the down-thrown side. Three 14 C ages of charcoal and soil humus buried by fan alluvium indicate that faulting probably occurred between 1400 and 1100 yr B.P. The soil that formed in the fan alluvium is only slightly more developed than that in the East Cache Alluvium, and the weak development of both soils indicates a geologically recent age that is consistent with the radiocarbon ages obtained for these deposits.

Oklahoma↗
USGS1987

Rocky Mountains

The Rocky Mountain region is one of the most topographically distinct and impressive parts of North America. The Rocky Mountains rise abruptly above the bordering regions, particularly on the east and northeast where they are flanked by plains, less so on the west and southwest where they are bounded by high plateaus. The Rocky Mountains comprise more than 100 individually named ranges that form a belt extending for slightly more than 5,000 km, from near Santa Fe, New Mexico, on the south to the Bering Sea on the north (Fig. 1). The belt varies in width from less than 100 km in the Canadian Rockies to nearly 600 km in the Middle Rockies of Wyoming and northeast Utah. The summits of the ranges rise 1,500 to 2,100 m above adjacent lowlands, to heights 1,800 to 4,400 m above sea level. The Southern Rockies of Colorado have the greatest amount of area, between 3,300 and 4,400 m, and the highest peak, Mount Elbert (4,400 m). The largest area of low mountains is in the Northern Rockies of Idaho and Montana, where summits are commonly only 2,100 to 2,400 m above sea level. A substantial part of the Rocky Mountain region consists of lowlands, in the form of basins and fault-bounded troughs and trenches that lie between ranges. The Rocky Mountain Trench is perhaps the most spectacular fault-bounded lowland, even if it is not the most representative. It extends north from Flathead Lake, Montana, more than 1,500 km, and forms

Book chapter↗
USGS1976

Bog stratigraphy, radiocarbon dates, and Pinedale to Holocene glacial history in the Front Range, Colorado

Radiocarbon dates and stratigraphic cores from bogs, kettle ponds, and former ice-marginal lakes on the east and west sides of the Front Range, Colo., between lat 40°00' and 40°24' N. suggest that (1) valley glaciers of Pinedale age began to recede from their terminal positions between about 14,600 and 13,000 yr ago, (2) revegetation of glaciated areas at altitudes of 2,600-2,900 m (8,600-9,500 ft) was complete by 11,000-10,000 yr ago, (3) at one site, 3,500±1,000 yr elapsed before peat began to form after deglaciation, (4) the formation of bogs within the glaciated areas kept pace with glacier recession in a general way, beginning at progressively later times as deglaciation proceeded upward, (5) Pinedale glaciers had disappeared or were reduced to small remnants by about 8,000 yr ago, (6) moraines that have been mapped as belonging to the early stade of Pinedale Glaciation are no younger than 13,000 yr B.P. and may be older than 14,600 yr, and those delimiting what has been mapped as late stade are no younger than about 7,600 yr B.P. and are probably older than 7,800 yr, and (7) most of the till mapped as Pinedale was deposited between about 14,600 and 8,000 yr ago.

Colorado↗