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	Alluvial Fan Flooding
		The Tortolita piedmont consists mainly of the dissected remnants of ancient fans.
		The alluvial fans that are inset into these dissected remnants are composed mainly of sand.
		This is because the fan apexes are not at the mountain front.
	www.nap.edu /books/0309055423/html/100.html (573 words)

	* Alluvial fan - (GIS): Definition
		Alluvial Fan - A low, outspread, relatively flat to gently sloping mass of loose rock material, shaped like an open fan or segment of a flattish cone, deposited by a stream at a place where it issues from a narrow valley onto a plain.
		Alluvial fan deposits are among the most common surficial sediments in mountainous terrain.
		AO An alluvial fan inundated by 100-year flooding (usually sheet flow on sloping terrain), for which average flood depths and velocities have been determined; flood depths range from 1 to 3 feet.
	en.mimi.hu /gis/alluvial_fan.html (235 words)

	Alluvial fan Summary
		This fan shape can also be explained with a thermodynamic justification: the system of sediment introduced at the apex of the fan will tend to a state which minimizes the sum of the transport energy involved in moving the sediment and the gravitational potential of material in the cone.
		Alluvial fans are most likely to be found in desert areas subject to periodic flash floods from nearby thunderstorms in local hills.
		Alluvial fans are very common around the margins of the sedimentary basins of the Basin and Range province of southwestern United States and northern Mexico.
	www.bookrags.com /Alluvial_fan (1893 words)

	RBF Consulting - Community - Papers/Presentations
		Alluvial fans are a dominant feature in the arid southwest where it is estimated that 15 to 25 percent of the area is covered by fans.
		The morphology of an alluvial fan is dependent upon a complex interaction of several variables which include: (1) area, mean slope, and vegetative cover of the source area, (2) slope of the stream channel, (3) discharge and climatic environment, and (4) geometry of the mountain front, adjacent fans and valley floor.
		Alluvial fan design discharges from the watershed hydrology utilized for the hydraulic analysis should include an appropriate "bulking factor" to increase clear water discharges to account for sediment in the total flow volume.
	www.rbfconsulting.com /papers/philips_ascepp4.html (2746 words)

	Alluvial Deposits
		Alluvial fans are flat to gently-sloping masses of loose rock material (largely sand and gravel) that are shaped like an open fan.
		There, displaced sediments in some alluvial fans on the west flank of the Sangres document that the bordering faults of the range were active as recently as 7,500 to 7,800 years ago.
		Some alluvial fans at the interface of the San Luis Valley and the west flank of the Sangres were displaced five to seven feet by faulting as recently as 7,500 to 7,800 years ago.
	www.uni.edu /~andersow/alluvialdeposits.html (748 words)

	Summary: Alluvial Features, Fans
		Fans are apron-like deposits of granular debris that extend from the base of a mountain front to a lowland below.
		Fans range in extent from meters to kilometers and in height from centimeters to tens of meters.
		Alluvial fans are formed by the sequential deposition of sediments carried by episodic streams that issue from water courses in mountain fronts onto broad, open areas where the streams spread out, lose speed, and dump their sediment loads.
	www.tec.army.mil /research/products/desert_guide/lsmsheet/lsfans.htm (1082 words)

	AllRefer.com - alluvial fan Information
		Alluvial fans are cone-shaped landforms that form at the base of slopes, near the mouth of a mountain canyon.
		An alluvial fan results when a sediment-laden stream or river rapidly deposits its load of gravel and silt as its speed is reduced on entering a plain.
		The surface of such a fan slopes outward in a wide arc from an apex at the mouth of the steep valley.
	www.allrefer.com /alluvial-fan (294 words)

	Erosion Control -- Holding Back the Sands of Time: Challenges for New Communities in Lands of Little Rainfall
		Alluvial fans are attractive places to live because of their elevation above valley floors, but they may pose hazards from infrequent dry-mantle flooding events.
		Interestingly, the active fan apex was not found at the head of the fan, as might be expected, but farther down from an entrenched channel that, House observed, had been capable of conveying the majority of discharges associated with the flooding events of the 1990s.
		If a person were to observe time-lapse photography of fan development over millions of years, he or she would see the main stem wandering from one side of the fan to the other.
	www.forester.net /ec_0003_holding.html (3372 words)

	Aspects of alluvial fan shape indicative of formation process: A case study in southwestern California with application ...
		The radial slope of fans where debris flow processes dominated is constant while fluvially-fed fans have a concave-upward shape.
		Fan length and surface gradient are inversely correlated: debris flow fans are shorter and steeper (>15°) than their fluvial counterparts.
		Citation: Williams, R. Zimbelman, and A. Johnston (2006), Aspects of alluvial fan shape indicative of formation process: A case study in southwestern California with application to Mojave Crater fans on Mars, Geophys.
	www.agu.org /pubs/crossref/2006/2005GL025618.shtml (344 words)

	Geology of Death Valley National Park
		Although rainfall is scarce in the valley, water is the creative force that builds Death Valley's alluvial fans.
		As Death Valley deepens and tilts, older alluvial fan channels are permanently abandoned, while new channels cut deep trenches on their way to the base of the fan.
		No doubt countless fans have formed since the opening of Death Valley about 3 million years ago, but those earlier fan deposits are now buried thousands of feet beneath younger fans and the valley floor.
	wrgis.wr.usgs.gov /docs/parks/deva/rfan.html (535 words)

	Alluvial Fan Flooding
		Fans ranged from fully active, where flooding or debris flows could occur anywhere on the fan, to incised, where the bulk of the fan is not subject to flooding.
		Alluvial fans evolve through geologic time, and their evolution is affected by climate change and tectonics, and therefore a wide variety of fan morphologies can be observed, from the ideal smooth surface on which flow paths can be predicted only with great uncertainty to deeply incised fans with flow confined to a single channel.
		Fans differ from pediments, some of which are cone-shaped, in that fans are formed by the accumulation of sediment, while pediments are erosional surfaces that are usually covered by a thin veneer of alluvium and colluvium.
	www.nap.edu /readingroom/books/all (3103 words)

	Chapter 5: An Evaluation of Alluvial Fan Agriculture
		These fans are formed primarily from the erosion and redeposition of older Pleistocene and early Holocene alluvial fans found farther upslope.
		Hence, fans far from the mountain front or fans with small drainage basins are most suitable for water distribution on floodwater fields with a minimum of human intervention and labor.
		Channel fans aggrading on bottomland in larger washes during Hohokam occupation would have been flooded by storms similar to the one in late August; that flow did not overflow onto the current surfaces of the prehistoric channel fans because of the present entrenchment of active stream channels.
	www.uapress.arizona.edu /onlinebks/fish/chapter5.htm (3331 words)

	ALLUVIAL FAN - Mojave Desert - Glossary of Terms and Definitions
		ALLUVIAL FAN - A fan-shaped sloping deposit of alluvium on a flat plain, whose source is usually a narrow canyon located at the head of the fan.
		Stream Terraces and Older Surfaces - Mojave Preserve - California...In the distance, the surface of an older quaternary alluvial fan is preserved intact (partly due to a resistant caliche bed preserved at the surface).
		Alluvial Fans in Death Valley...From the mouth of Golden Canyon, the top of Artist's Drive, or Dante's View, you have a sweeping view across Death Valley toward...
	www.mojavedesert.net /glossary/alluvial-fan.html (607 words)

	NWO - Orbital signatures in alluvial fan sequences? A key example from the Miocene of Spain
		Alluvial fan architecture typically reveals coarsening upward sequences on various scales that are commonly related to pulsating tectonics and/or autocyclic processes while climate is generally being neglected.
		We propose to study the sedimentary signatures and architecture of small-scale, coarse-clastic fan systems in the Calatayud-Teruel Basin, Spain, which developed along an active basin margin in a semi-arid climate setting during the late Miocene.
		The challenge is to demonstrate the astronomical signal in alluvial fan successions from coeval proximal settings in the C-T Basin, to reconstruct processes and mechanisms of astronomical climate forcing and control on alluvial fan sedimentation, and to establish similarities and differences with the effects of tectonic and autocyclic forcing.
	www.nwo.nl /projecten.nsf/pages/2300130876 (227 words)

	Bryce Canyon National Park: GEODETECTIVE Program (Site not responding. Last check: )
		Alluvial fans and deltas are sedimentary landforms deposited by flowing water.
		Alluvial fans are often found at the base of arid / semiarid mountain ranges where intermittent streams flow.
		Alluvial fan examples can be found in Death Valley National Park and along the sides of the Colorado River at Grand Canyon National Park.
	www.nps.gov /archive/brca/geodet/geodet_fansanddeltas.html (953 words)

	The San Bernardino County Museum
		Alluvial fan sage scrub is a sub-type of coastal sage scrub found on the alluvial fans and flood plains of the coastal side of the San Bernardino and San Gabriel Mountains.
		The climatic features of alluvial fan sage scrub are similar to those for Coastal Sage Scrub, but differ in the frequency and intensity of surface flooding that occurs within the habitat.
		Alluvial Fan Sage Scrub Communities have been severely altered by flood control activities that circumvent the periodic flooding necessary to maintain the habitat, leading to the gradual type conversion of this unique community type.
	www.co.san-bernardino.ca.us /museum/exhibits/etiwandafan/alluvialfan_sagescrub.htm (273 words)

	Alluvial Fans - Physical Geology Project
		Alluvial fans form because material is constantly being eroded in narrow valleys above the fan.
		Alluvial Fans normally form at the base of topographic features where there is a marked break in the slope.
		Alluvial fan hazard areas are those areas on a fan that have the potential to damage or harm the health or welfare of the community.
	www.earlham.edu /~pipersh/Geo/2005fans.htm (437 words)

	DLESE description of Alluvial Fan Flooding
		Alluvial fans are gently sloping, fan-shaped landforms common at the base of mountain ranges in arid and semiarid regions such as the American West.
		Floods on alluvial fans, although characterized by relatively shallow depths, strike with little if any warning, can travel at extremely high velocities, and can carry a tremendous amount of sediment and debris.
		Alluvial Fan Flooding attempts to improve our capability to determine whether areas are subject to alluvial fan flooding and provides a practical perspective on how to make such a determination.
	www.dlese.org /library/catalog_NAP-5364.htm (269 words)

	[No title]
		Davis (1905) took an evolutionary standpoint and suggested that alluvial fans occurred in a youthful stage in the arid lands cycle of erosion.
		Denny (1967) suggested that alluvial fans represent a dynamic equilibrium in the transportation of course debris from mountain range to the adjacent basin.
		In addition to the attention paid to fan deposits, alluvial fan researchers have recognized that fan entrenchment can be either temporary or permanent, and distinguishing between the two seems to be critical to the correlative cause (Ritter et al., 1995).
	geog.tamu.edu /~jlg4551/689final.doc (2329 words)

	Southern California Areal Mapping Project home
		Tributary canyons commonly terminate in alluvial fans that debouch onto the valley floors of the through-going axial valleys.
		This is a space-shuttle image of a single giant alluvial fan in the Gansu Province, China (source: NASA photograph STS048-610-034, September 1991, obtained from the NASA Earth from Space archive of space-shuttle images).
		During any given alluvial cycle, the latter once were part of a continuous sediment package that extended from canyon-head to canyon-mouth; however, upstream components now are isolated, relict bodies of sediment scattered along the canyon bottom.
	scamp.wr.usgs.gov /scamp/html/scg_surf_alluv.html (1968 words)

	Building Homes on Southern California’s Alluvial Floodplains
		Many land-use decisions on alluvial fan floodplains are occurring in a void.
		The Task Force is charged with developing tools for better land-use decisions on alluvial fan floodplains, including a model ordinance for communities that are subject to these recurrent dangers.
		The Department of Water Resources submitted an application to implement the Alluvial Fan Task Force to FEMA in February 2005 from a Pre-Disaster Mitigation Grant.
	www.floodplain.org /Alluvial_Fan_Housing.htm (1289 words)

	Western City Magazine
		Many mayors and council members have never heard of an alluvial fan and may not be aware that a portion of their city is on a floodplain because the Federal Emergency Management Agency (FEMA) doesn't map floodplains that extend beyond the limits of a Flood Insurance Rate Map (FIRM).
		Elected officials are unaware that new developments may be subject to alluvial fan flooding because FEMA hasn't mapped many alluvial fan floodplains that are experiencing unprecedented growth.
		The task force is charged with developing tools for better land use decisions on alluvial fan floodplains, including a model ordinance for communities that are subject to these recurrent dangers.
	www.cacities.org /index.jsp?zone=wcm&previewStory=23652 (1258 words)

	Rocky Mountain National Park - Horseshoe Park -- Alluvial Fan
		Alluvial Fan and Fan Lake from Rainbow Curves on Trail Ridge Road.
		In addition to tons of lighter rocks, gavel and sand creating a 42-acre alluvial fan.
		Unofficially called "Fan Lake", it has provided new habitats for wildlife displaced by the Lawn Lake flood's debris.
	www.rmnp.com /RMNP-Areas-HorseshoePark-AlluvialFan.html (234 words)

	[No title] (Site not responding. Last check: )
		Alluvial fans are fan-shaped deposits of water-transported material (alluvium).
		Consequently, alluvial fans tend to be coarse-grained, especially at their mouths.
		Alluvial fan and center-point irrigation in Dixie Valley, California.
	darkwing.uoregon.edu /~millerm/fan.html (110 words)

	Fan Tan - Search Results - ninemsn Encarta (Site not responding. Last check: )
		Fan Tan, Chinese gambling game and a Western card game.
		The gambling game is played on a table, the top of which has a square marked out, the sides...
		Alluvial Fan, fan-shaped mass of sediment that is deposited when a mountain stream flows out from a canyon onto a plain.
	au.encarta.msn.com /Fan_Tan.html (168 words)

	Alluvial Fan & Flash Floods - Anza Borrego SP - Earthcaches on Waymarking.com (Site not responding. Last check: )
		An alluvial fan is made up of sediment that is sporadically transported out of a relatively narrow mountain canyon and deposited at the mouth (end) of the narrow valley where it opens up into flatter terrain.
		Once the water reaches the lower slope of the alluvial fan, the water slows and the larger particles begin falling out of the water.
		As you look at the rocks and boulders in the canyon and alluvial fan, you will find that just about all of them are smooth and rounded.
	www.waymarking.com /wm/WM5NQ (1236 words)

	Hydrogeology of the Bakersfield area of the San Joaquin Valley (Site not responding. Last check: )
		Deposition of the alluvial fan is the geologic response to this change in slope and to the transition from confined to unconfined flow.
		Water runoff from the Sierras flows from NE to SW down the bed of the Kern River onto the alluvial fan where the water slowly seeps from the river bottom into the distant margins of the fan.
		Although the presence of arsenic at the foot of the fan is interesting, it is not a concern for Bakersfield since the city draws its water from the mouth of the fan, far removed the mixing zone.
	www.sjgs.com /groundwater/groundwater.html (1428 words)

	SEMP - Venezuela’s 1999 Massive Historic Alluvial Fan Flooding Event (Site not responding. Last check: )
		An alluvial fan is a gently sloping, cone- to fan-shaped landform created over thousands to millions of years by deposition of eroded sediments at the base of mountains.
		Alluvial fans evolve through geologic time, and their evolution is affected by climate change and tectonics, and therefore a wide variety of fan morphologies can be observed, from the ideal smooth surface on which flow paths can be predicted only with great uncertainty to deeply incised fans with flow confined to a single channel.
		At the alluvial fan apex, the debris-flow volume exceeded the channel’s capacity, resulting in multiple stream “avulsions” and flows spreading debris throughout the community.
	www.semp.us /biots/biot_362.html (1982 words)

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