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Geomorphic Surfaces, Fluvial Erosion, and Landscape Evolution Geomorphic Surfaces, Fluvial Erosion, and Landscape Evolution.

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Presentation on theme: "Geomorphic Surfaces, Fluvial Erosion, and Landscape Evolution Geomorphic Surfaces, Fluvial Erosion, and Landscape Evolution."— Presentation transcript:

1 Geomorphic Surfaces, Fluvial Erosion, and Landscape Evolution Geomorphic Surfaces, Fluvial Erosion, and Landscape Evolution

2 Schoeneberger 2007 Lincoln NE What is the oldest point on this hillslope?

3 Geomorphic Surface Defined A portion of a landscape that can be defined by space and time. It may include multiple landforms. It is a mappable feature with definable borders. A geomorphic surface is two-dimensional. It has no thickness (Ruhe 1975).

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5 Utility and Scientific Value of Geomorphic Surfaces  Partitions the landscape into spatial units that originate from a common set of processes.  Provides the scientific principles that establish age (relative or actual) relationships among landscapes, landforms, and soils.

6 Elements of a Geomorphic Surface Depositional Depositional (formed by deposition of sediment). Erosional Erosional (formed by removal of earth material). Both may be present; but the deposition component is often removed by younger erosion.

7 E.E. Gamble Turkey Creek, IA Depositional Surface Late Wisconsin to Recent Erosional Surface

8 Geomorphic Surfaces ( oldest surface is on top Younger surfaces cross cut older surfaces) The principle of ascendency Establishes relative age relationships within a landscape

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10 E.E. GambleNC

11 Erosional Surface B

12 Wysocki inset relationship; northeast KS

13 E.E. Gamble Valley Forge, PA Depositional Surface Erosional Surface

14 Criteria for Identifying Geomorphic Surfaces Landscape morphometry Sediment bodies or packages Weathering profiles, paleosols including surface soils.

15 Recognition of Geomorphic Surfaces Requires: Field observations and use of spatial information (topo maps, aerial photos). Field identification of landscape features, landforms, and sediments resulting from erosion and/or deposition during a given time.

16 Age Tenets of Geomorphic Surfaces An erosional geomorphic surface is younger than any surface to which it ascends (cross cuts). An erosional component of a geomorphic surface is the same age as depositional component to which it descends.

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18 E.E. Gamble Ducktown, TN

19 Age Nuances ●An erosional surface is the same age as the depositional surface to which it descends, and therefore, no older than the youngest alluvium beneath depositional surface. ●The alluvium beneath a depositional surface may be a time transgressive deposit. Maximum age of a depositional surface equals basal alluvium age.

20 Age of Geomorphic Surfaces

21 E.E. Gamble Turkey Creek, IA Depositional Surface Late Wisconsin to Recent Erosional Surface

22 Geomorphic Surface (depositional) Buried Exposed Fan 1 Fan 2 Geomorphic Surface 2 (depositional) older burial = age of deposit younger

23 Daniels & Jordan, Huddleston What is the surface age on the Hatcher alluvium?

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26 E.E. Gamble Surry Scarp (middle vs. lower) Coastal Plain, NC

27 Faceted (Stepped) Surfaces Geomorphic evidence of erosion surfaces is a number of inclined facets (stepped surfaces) on a hillslope. The facets must be repeating and traceable across hillslopes. Until geologic erosion obscures the morphometric relationships these facets are discernible geomorphic surfaces.

28 Faceted (stepped) surface remnants (typically only erosional component remains) Ozarks, MO

29 Gamble (1982) MO Ozarks Soil-Geomorphic Study S1

30 s1 s2s2 e4 e5 ?? s3

31 Ozarks, MO

32 S-2 Surface Laclede County MO Gamble

33 E-4 Surface Laclede County MO

34 Exceptions: Bedrock control ( tectonic displacement, mass movement )

35 EROSIONAL AND DEPOSITIONAL SURFACES 1. deposition of BED 2 2. stabilization and pedogenesis 3. Fluvial erosion down cutting or headward. BED 1 (thinly interbedded silt and sand) BED 2 (massive unconsolidated sand) buried soil A soil B incision Wysocki et al, (2000)

36 EROSIONAL AND DEPOSITIONAL SURFACES 3. erosion 4. stabilization and pedogenesis BED 1 (thinly interbedded silt and sand) BED 2 (massive unconsolidated sand) buried soil A soil B soil C soil D Wysocki et al, (2000) Two less developed soils on the younger erosional surface More developed soil on older surface There is not necessarily a 1:1 relationship of soil to geomorphic surface.

37 Fluvial Landscape Erosion & Evolution Fluvial Landscape Erosion & Evolution

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39 Fluvial Erosion effects / controls much of the earth’s surface. Fluvial erosion establishes relationships and provides tools for assessing relative age of portions of the landscape and the soils on them. [ Constructional landscapes (e.g. young lava flows, intense eolian deposition, etc.) play by a different set of rules. ]

40 FLUVIAL EROSION SURFACES Start from a controlling stream. Move up interfluve flanks toward divide. Cut older geomorphic surfaces. Ruhe (1967)

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42 FLUVIAL EROSION SURFACES Erosion surface profile is curvate and concave upward toward divide. Ruhe (1967)

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44 Surface 3 Surface 2 Surface 1

45 stepped geomorphic surfaces; Las Animas Arroyo (Caballo Reservoir area), NM Schoeneberger / Wysocki

46 FLUVIAL EROSION SURFACES l Erosion strips weathering products of older surfaces forming a young, fresh surface. l New soil forming cycle begins.. Ruhe (1967)

47 Late Sangamon Pediment Wisconsin age erosion surface Adair Soil – Loess/Paleosol Fine Oxyaquic Vertic Argiudoll Shelby Soil Loess/Till Fine-loamy Typic Argiudoll

48 FLUVIAL EROSION SURFACES Ruhe etal. (1967) l Divides remain as a stable portion of the landscape until beveled by an encroaching erosion surface.

49 Ozarks, MO Drew Quadrangle MO After Gamble 1993

50 EROSIONAL AND DEPOSITIONAL SURFACES 1. deposition of BED 1 BED 1 (thinly interbedded silt and sand)

51 BED 1 (thinly interbedded silt and sand) BED 2 (massive unconsolidated sand) buried soil A buried soil B buried soil C buried soil D BED 3 (massive sand and gravel) buried soil E BED 4 (dune sand)

52 EROSIONAL AND DEPOSITIONAL SURFACES 1. deposition of BED 1 2. stabilization and pedogenesis soil A

53 BED 2 (massive unconsolidated sand) BED 1 (thinly interbedded silt and sand) EROSIONAL AND DEPOSITIONAL SURFACES Daniels and others (1971) SURFACE A SURFACE B SURFACE STABILIZATION AND SOIL FORMATION

54 EROSIONAL AND DEPOSITIONAL SURFACES 1. deposition of BED 1 2. stabilization and pedogenesis 3. deposition of BED 2 BED 1 (thinly interbedded silt and sand) BED 2 (massive unconsolidated sand) buried soil A

55 EROSIONAL AND DEPOSITIONAL SURFACES 3. deposition of BED 2 4. stabilization and pedogenesis BED 1 (thinly interbedded silt and sand) BED 2 (massive unconsolidated sand) buried soil A soil B

56 EROSIONAL AND DEPOSITIONAL SURFACES 3. deposition of BED 2 4. stabilization and pedogenesis 5. erosion BED 1 (thinly interbedded silt and sand) BED 2 (massive unconsolidated sand) buried soil A soil B incision

57 EROSIONAL AND DEPOSITIONAL SURFACES 5. erosion 6. stabilization and pedogenesis BED 1 (thinly interbedded silt and sand) BED 2 (massive unconsolidated sand) buried soil A soil B soil C soil D

58 EROSIONAL AND DEPOSITIONAL SURFACES 5. erosion 6. stabilization and pedogenesis 7. deposition of BED 3 BED 1 (thinly interbedded silt and sand) BED 2 (massive unconsolidated sand) buried soil A soil B buried soil C buried soil D BED 3 (massive sand and gravel)

59 EROSIONAL AND DEPOSITIONAL SURFACES 7. deposition of BED 3 8. stabilization and pedogenesis BED 1 (thinly interbedded silt and sand) BED 2 (massive unconsolidated sand) buried soil A soil B buried soil C buried soil D BED 3 (massive sand and gravel) soil E

60 EROSIONAL AND DEPOSITIONAL SURACES 8. stabilization and pedogenesis 9. deposition of BED 4 BED 1 (thinly interbedded silt and sand) BED 2 (massive unconsolidated sand) buried soil A buried soil B buried soil C buried soil D BED 3 (massive sand and gravel) buried soil E BED 4 (dune sand)

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