1. Fluvial Processes and Geomorphic Environments

2. Fluvial Processes Erosion headward dissection vertical incision lateral migration Transport bed load suspended load dissolved load Deposition deltas natural levee backswamp alluvial fan

3. Fluvial erosion, transport, and deposition by flowing water. des excludes glaciofluvial systems Sediments: coarse to fine grained, commonly stratified; texture and morphology depends upon deposition environment Landscapes: alluvial plain, canyonlands, river valley Landforms: arroyo, flood-plain step, meander, stream terrace Microfeatures: bar, groove, gully

4. Braided Stream Platte River near Louisville, NE

5. Landscape: flood plain, river valley; Landforms: meanders, oxbow lake, scroll bar ; Laramie R., WY Wysocki

11. Ritter et al., 1995

13. ( Ritter, et al., 1995 )

14. Benoit MS, AR USGS 7.5’ quad

19. MS River Oxbow Deer Creek Source

21. Wysocki Holocene clay capped stream terrace (Sharkey soil); Washington Co., MS

22. Wysocki Sharkey soil profile ; Washington Co., MS Sharkey Series very fine, Chromic Epiaquert

23. Wysocki Natural levee to backswamp transition. Dundee Series Fine Silty Typic Endoaqualf Sunflower Co. MS

24. Landscape: river valley; Landforms: scroll bars, oxbows, channelized river ; Miss. R., AR / MS Wysocki

25. Landscape: loess-covered till plain; Landform: entrenched stream, meanders; Lincoln, NE Wysocki

26. ( NASA id 16633 ) Landscapes : river valley, gulf (water) Landforms : delta (birds foot) channel, natural levee Mississippi R., LA (1999; natural color)

27. Landform: stream terraces ; Snake R., near Jackson Hole, WY Wysocki

28. Landforms: canyon, strath terrace; Black Canyon (Gunnison R.), CO Schoeneberger

29. Fill Terrace

30. Erosional terrace

31. Alluvial Fans Alluvial fans compared to perennial streams – cross-sectional profile - longitudinally convex –flashy flow system – sediment composition: Degree of Sorting - < stream alluvium Degree of Rounding - < stream alluvium Clast supported - > stream alluvium –debris / mudflow - common in proximal areas

32. Landforms : low mountains, interfluves, alluvial fan, braided river ; Brodeur Peninsula, Baffin Is, Nunavut, CAN ( GSC#2002-205 )

36. Insert graphic from Lambert, 1996 ( NM, 2002 ) Landform: alluvial fan; Parent Material: fan alluvium; Organ Mountains, Las Cruces, NM Schoeneberger

37. Landform: alluvial fan ; Death Valley, CA. What is the grayer deposit to left?

38. Landform: alluvial fan; Cedar Creek Fan MT Ennis, MT USGS 7.5’ Quad

39. Ritter, et al, 1995

41. How do you distinguish a low gradient alluvial fan from a stream terrace?

42. One Mile Alluvial Fans Stream Terrace

43. active alluvial fan fan remnant ( fan surface abandoned but substantially intact; inset fan-head trenches, terraces) eroded fan remnant ( little fan surface remains; e.g. < 50 % of original fan surface ) eroded fan remnant sideslopes ( no fan surface remains; hillslope elements dominate ) original fan surface Evolutionary stages of alluvial fan landforms ( cross-sectional profiles ) PJS, 2004 Inset fan

44. ( Peterson, 1981; fig. 3 ) Basic Landform elements of Basin & Range terrain – southwestern US A - alluvial fan B - ballenas F - alluvial flat M - mountains (LS) P - fan piedmont (LS) S - fan skirt Y - playa bolson, semi-bolson Landscape :

45. A - alluvial fan V - interfan valley P - fan piedmont ( Peterson, 1981; fig. 7 ) Drainageway Types (FFP). 1 - interfan - valley drainageway 2 - fanhead trench 3 - onfan drainageway 4 - interfan-valley drainageway Inset fan fan remnant

46. Landscape: bajada in a semi-bolson ; Landforms: ballena, eroded fan remnants, eroded fan-remnant sideslopes, inset fan, terraces ; Organ Mountains., Las Cruces, NM Schoeneberger

47. Hillslope Evolution : back wearing side slopes and pedimentation S = ?? a = ?? P = ?? c = ?? ps = ?? ( Peterson, 1981; fig. 16 )

48. ( Peterson, 1981; fig. 15 ) Hillslope Evolution & Hillslope - Profile Positions: - 2 dimensional - backwearing slope convergence - divide lowering

49. ( Peterson, 1981; fig. 9 ) p - ( partial ballenas ) s - ( relict summit area )

50. Landscape: bajada in a semi-bolson ; Landforms: eroded fan remnants, eroded fan- remnant sideslopes ; Organ Mountains., Las Cruces, NM Schoeneberger

51. ( adapted from Peterson, 1981; fig. 17 ) c = crest m = summit s = shoulder b = backslope f = footslope t = toeslope x = drainageway Variations of hillslope-profile positions in southwestern US Landscapes

52. Landscape: bajada ; Landform: eroded fan remnants, inset terraces ; Tortugas Mtn. view (Organ Mountains., Las Cruces, NM ) Schoeneberger

53. ( Peterson, 1981; fig 11 ) 1 - original fan surface 2 - first gullying sequence ( or its remnants of pediments, footslopes ) 3 - second gullying sequence ( or its remnants of pediments, footslopes ) 4 - third gullying sequence ( or its remnants of pediments, footslopes ) Landscape Evolution : Typical Erosion Sequences of Fan Piedmonts Generalized (Erosional) Evolution of Divides a – relict fan-piedmont surface (1) b - asymmetric, relict fan piedmont surface and new, encroaching pediments c - ridgeline remnants of pediments 2 & 3 d - late stage erosion of “c”

55. Landform : slot canyon Escalante Natl. Mon., UT Schoeneberger slot canyon – A long, narrow, deep and tortuous channel or drainageway with sheer rock walls eroded into sandstone or other sedimentary rocks, especially in the semi-arid western USA (e.g. Colorado Plateau); subject to flash flood events; depth to width ratios exceed 10:1 over most of its length and can approach 100:1; commonly containing unique ecological communities distinct from the adjacent, drier uplands. NSSH