Geomorphic Surfaces, Fluvial Erosion, and Landscape Evolution

What is the oldest point on this hillslope? What is the oldest point on this hillslope? What controls the soil distribution? Soil development? Soil age? What does this hillslope sequence tell about the landscape evolution? Lincoln NE Schoeneberger 2007

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). Fundamental definition of a geomorphic surface.

Is this landscape or hillslope the same age throughout Is this landscape or hillslope the same age throughout? Where do the age and/or sediment composition change?

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.

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

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

Establishes relative age relationships within a landscape Geomorphic Surfaces ( oldest surface is on top Younger surfaces cross cut older surfaces) The principle of ascendency Establishes relative age relationships within a landscape The oldest geomorphic surface occurs at the highest stable elevation.

Stream down cutting exposes soil and strata Stream down cutting exposes soil and strata. An younger erosion surface cutting a stable surface. NC E.E. Gamble

Erosional Surface B

inset relationship; northeast KS The site history interpreted: Deposition of brown unit, channel cutting, channel fill. inset relationship; northeast KS Wysocki

Erosional Surface Depositional Surface E.E. Gamble Valley Forge, PA The depositional surface along the stream forms primarily by stream (depositional) processes ( up-valley sediments) , but also receives hillslope sediment from above. The two surfaces are the same age. One is depositional, the other is erosional. E.E. Gamble Valley Forge, PA

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

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.

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.

Surface B cross cuts Surface A, and Beds 1 and 2 Surface B cross cuts Surface A, and Beds 1 and 2. What are the relative ages of each?

A man induce erosion cycle. What is the age of the landscape segments A man induce erosion cycle. What is the age of the landscape segments. Where is the stable geomorphic surface and soil? Ducktown, TN E.E. Gamble

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.

Age of Geomorphic Surfaces The upper alluvium has an age of 10 ka. The depositional surface over the alluvium is no older than 10 ka. The erosional surface that descends to the depositional surface must be the same age (10 ka).

Late Wisconsin to Recent Erosional Surface Depositional Surface Landscape example of the previous concept. E.E. Gamble Turkey Creek, IA

Geomorphic Surface 2 (depositional) older burial = age of deposit younger Fan 2 Geomorphic Surface (depositional) Buried Exposed A geomorphic surface can be eroded (destroyed) or buried and preserved. What age relationships exist in the sketch above? Does the principle of ascendency hold here? Fan 1

What is the surface age on the Hatcher alluvium? Given the ages in the alluvial deposits, what are the ages of the surfaces? Daniels & Jordan, Huddleston

A series of stepped surfaces forms a record of landscape evolution.

Stratigraphic and geomorphic relationships occur at various scales from hillslope to regional.

Surry Scarp (middle vs. lower) Coastal Plain, NC E.E. Gamble Geomorphic relationships are not always obvious, and may require field study and time to decipher. Surry Scarp (middle vs. lower) Coastal Plain, NC E.E. Gamble

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.

Faceted (stepped) surface remnants (typically only erosional component remains) Successive downcutting or erosion cycles may remove most or all of the previous depositional surfaces, but can leave remnants of the erosional surfaces. This can result in facets (consistent and repeating slope inflections) across a hillslope or landscape area. Ozarks, MO

Gamble (1982) MO Ozarks Soil-Geomorphic Study Note I didn’t get the S1 summit contrasting enough; labeled as S1 in the NE and SE ridge area, w red arrows. S1

s3 Note: Should the e4 extend out the crest in the foreground? Not shown is original field sheet, but shown in Phil & Doug’s slide…. s1 e4 s2 ?? e5

Ozarks, MO

S-2 Surface Laclede County MO Gamble

E-4 Surface Laclede County MO Gamble

Exceptions: Bedrock control ( tectonic displacement, mass movement )

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

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

Fluvial Landscape Erosion & Evolution

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. ]

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

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

Surface 1 Surface 2 Surface 3

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

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

Late Sangamon Pediment Wisconsin age erosion surface Adair Soil – Loess/Paleosol Fine Oxyaquic Vertic Argiudoll Shelby Soil Loess/Till Fine-loamy Typic Argiudoll Adair = Fine, smectitic, mesic Oxyaquic Vertic Argiudolls = very deep, somewhat poorly drained soils that formed in loess and erosional sediments (pedisediment) over a truncated paleosol developed in weathered (primary carbonates removed) pre-Illinoian glacial till. Shelby = Fine-loamy, mixed, superactive, mesic Typic Argiudolls = very deep, well drained soils formed in less weathered pre-Illinoian glacial till with primary carbonates in lower B and C horizons.

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

Drew Quadrangle MO After Gamble 1993 Ozarks, MO

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

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

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

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

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

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

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

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

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

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

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