1

Geology Colloquium

Dr. Ellen HermanBucknell University

Interpreting Flow and Sediment Transport in Karst Springs

Thursday March 1stTalk at 4, refreshments at 345 PM

310 White Hall

Hollows, Wind Gaps, Water Gaps, and Ancient Rivers

GEO 321 Lecture 15

Armoring of HollowsArmoring of Hollows

Topographic InversionW-Shaped HollowsGully Gravure ( Bryan, 1940)

2

Dip

Slop

eScar

p Sl

ope

Asym

met

rical

Hog

back

(Hom

oclin

alRi

dge)

Sym

met

rical

Hog

back

Antic

line

Axis

Appr

ox.

WV Rt28/55

North Fork Mtn., N of Seneca Rocks, WV

Area on Next Slide

Spur or “Nose”

Hillslope “Hollow” Boulder Source: Tuscarora SS

“Cliffs”

3

Bouldery Hollow

Boulder-Free Nose

Bouldery Hollow Bouldery Hollow

Boulder-Free Nose

Gully Gravure, North Carolina

Image from Bryan, Kirk, 1940, Gully Gravure –– A Method of Slope Retreat: Journal of Geomorphology, v. III, no. 2, p. 89-107.

Gully Gravure, North Carolina

Modified from Bryan, Kirk, 1940, Gully Gravure –– A Method of Slope Retreat: Journal of Geomorphology, v. III, no. 2, p. 89-107.

Z’ Z

Paleo-topography

“W”-Shaped Channel

4

Modified from Bryan, Kirk, 1940, Gully Gravure –– A Method of Slope Retreat: Journal of Geomorphology, v. III, no. 2, p. 89-107.

Topographic InversionGully Gravure, North Carolina

Valley Type ClassificationThornbury, 1969

• Antecedent (Predates Structures)• Superposed (Super-imposed)• Consequent (Flows Down Bedding Dip)

–vs. Obsequent (Flows Opposite Dip)• Subsequent (Eroded into Weak Rocks)

New River: 2nd Oldest River in the World???

photo by John Remo

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New River: 2nd Oldest River in the World?

River had to be in place before folding of

resistant rocks that now form ridges

Logic behind the statement: New River, unlike other rivers, cuts almost completely through the structures (Faults, folds, etc.) of the Appalachian Mountains, and therefore it must been in that route before the mountains formed, over 200 million years ago!

River maintained path throughout

uplift!

• Antecedent• Superposed• Consequent• Obsequent• Subsequent

New River: 2nd Oldest River in the World?

Alternative 1:River formed on

old Tertiaryerosion surface

(shown in A), then landscape was

rejuvenated & River was superimposed on folded Appalachians.

Alternative 2: River was

superimposed in segments from

shale- or limestone-dominated valleys.

• Antecedent • Superposed• Consequent• Obsequent• Subsequent

Live Anticline, Breached by Water Gap

Live Folds -Consequent Drainage

Short, N. M., and Blair, R. W., 1986, Geomorphology from Space, NASA daac.gsfc.nasa.gov/DAAC_DOCS/geomorphology/

GEO_2/GEO_PLATE_T-42.HTML

6

Homoclinal Ridges, near Rawlings, Wyoming

Short, N. M., and Blair, R. W., 1986, Geomorphology from Space, NASA daac.gsfc.nasa.gov/DAAC_DOCS/geomorphology/

Obsequent(Flows Opposite

Dip)

CR

CV

WT BR

HFIMNF

Antecedent (Predates Structures)Superposed (Super-imposed)Consequent (Flows Down Bedding Dip)

vs. Obsequent (Flows Opposite Dip)Subsequent (Eroded into Weak Rocks)

Seven Bends of the North Fork Shenandoah River

Woodstock, VA •Subsequent

•Eroded into Weak Rocks (Martinsburg Shale)

7

Seven Bends, North Fork Shenandoah River, near Woodstock, VA

Subsequent Eroded in Weak

Martinsburg Shale

Seven Bends of the North Fork Shenandoah River

Woodstock, VA •Subsequent

•Eroded into Weak Rocks (Martinsburg Shale)

Passage Ck.Fort Valley, VA

Subs

eque

nt ,

Erod

ed in

Wea

k D

evon

ian

Shal

e

8

Compton Gap, Blue Ridge Mtns., Shenandoah N.P.

Wind Gap: Consequent or Old Water Gap Surrounded by Peneplains?

Look at Topo Map near Woodstock Fire Tower

http://terraserver.microsoft.com/

Search for Strasburg, VALook at bends of Shenandoah R.Subsequent Streams, Water Gaps in

Massanutten Mtn. & Fort ValleyWind Gaps in Blue Ridge of VA

e.g. Compton Gap, Jenkins GapHarpers Ferry, WV

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CR

CV

WT BR

HFIMNF

Look at Topo Map

http://terraserver.microsoft.com/

Looked at Erosional terraces on Greenbrier River north of Ronceverte, WV

Depositional Terraces on the Ohio River near Chester and Arroyo, WV

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Dolls Gap, West Virginia• From

http://www.wvexp.com/index.php/Dolls_Gap•

Doll's Gap, or Dolls Gap, forms the famous "saddle" of Gap Mountain in West Virginia's eastern panhandle. A "wind gap," the formation was established long ago by a stream which once crossed the mountain; after years of uplifting, the stream abandoned the pass across the mountains.

Gaps in N Fork Mountain

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12

CR

CV

WT BR

HFIMNF

13

LANDSAT Image Courtesy Tim Warner & Duane NellisWVU Remote Sensing Lab

Geologic Overview of Canaan Valleya Billion Years of the Past and 10

Million Years into the Future

J. Steven KiteRobert E. Behling

WVU Geology & Geography

GeologicalMap of Canaan Valley

Cardwell, & others, 1968,

Geologic Map of West

Virginia: WVGES

Source: Kozar, Mark D., 1996, Geohydrology and Ground-Water Quality of Southern Canaan Valley, Tucker County, West Virginia, USGS Water Resources Investigations Report 96-4103, 67 p.

Generalized Cross-Section of the Bedrock Geology Along the Breached Blackwater Anticline, Canaan Valley

PRICE FORMATION

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Source: Kozar, Mark D., 1996, Geohydrology and Ground-Water Quality of Southern Canaan Valley, Tucker County, West Virginia, USGS Water Resources Investigations Report 96-4103, 67 p.

Generalized Cross-Section of the Bedrock Geology Along the Breached Blackwater Anticline, Canaan Valley

Hin

ge

Blackwater Ridge: ~ 10 million Years Ago?

PRICE FORMATION

Geology of

Canaan Valley

Streams Drain

Parallelto Valley

Chestnut Ridge: Analog to “Canaan” Area ~ 10 million Years Ago

Streams Drain Off Ridge Flanks

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Wind Gaps: Relicts of Drainage on Blackwater Ridge?

Blackwater R.

Possible Paleo-Drainage Routes: ~ 10 million Years Ago?

Blackwater River Piracy of Streams Flowing Off Old

Blackwater Ridge

Paleo-Drainage Routes: ~ 10 million Years Ago?

Dry Creek Piracy of

Blackwater Drainage

Blackwater River Piracy of Streams Flowing Off Old

Blackwater Ridge

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Southern Canaan Valley Will Be

Lost to Dry Fork Piracy

Northern Canaan Valley Will Grown as Ridges Retreat

Speculation on the Next 10,000,000

Years in “Canaan Valley”

Risi

ng R

idge

of

Pric

e Sa

ndst

one

Cortl

and

Valle

y

Glad

e Cr

eek

Valle

y

Risi

ng R

idge

of

Pric

e Sa

ndst

one

Cortl

and

Valle

y

Glad

e Cr

eek

Valle

y

May Be Lost to Dry Fork?

Risi

ng R

idge

of

Pric

e Sa

ndst

one

Cortl

and

Valle

y

Glad

e Cr

eek

Valle

y

Geology Colloquium

Dr. Ellen HermanBucknell University

Interpreting Flow and Sediment Transport in Karst Springs

Thursday March 1stTalk at 4, refreshments at 345 PM

310 White Hall

Paleohydrology & Paleoflood Hydrology

•See 2001 Lecture for more slides

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Prediction from Geomorphology & Holocene Stratigraphy

DepositsSlackwater: StageBedload: Tractive Force, Stream Power

PaleosolsInterruption of Stability

LandformsSlackwater Terraces

Tool Kits for the Paleohydrologist

• Vegetation Along Stream • Proxy Records, e.g. Tree Rings• Bedload Competence• Channel Geometry: Plan and Cross-

Section• Slackwater Deposits: Bath-Tub Rings

BedrockAlluvium

FloodplainFloodplainT1T1

T2T2

Channel ShelfDepositional Bar

TERRACE ASSEMBLAGE(oak, sassafras, dogwood,

mt. Laurel, white ash)

FLOODPLAIN FOREST(hackberry, black walnutamerican elm, sycamore)

RIPARIAN SHRUBS(alder, slippery elm,

box elder, red willow)

DEPOSITIONAL BAR(herbaceous vegetation;

willow, sycamore, or cottonwood seedlings)

Eric N. Davis, 2000. Modified from Osterkamp and Hupp, 1984.

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Dendrohydrology

Datable Flood Scar

Tractive Load Size• How to determine what moved.

– flake scars bruises on sheltered surfaces, multiple impact marks, Fe staining (Cheat), imbricated w/ tires, plastics, lumber, etc., aerial photography (BFR)

tau = τ = γ D Sγ = gamma = specific weight of waterD = depthS = gradient (slope)

Critical Tractive Force = tauc = τc = 166 d

d = grain diameter (mm)

Critical Tractive Force: Force Required to Move Particle of diameter = d

Remember?

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D = 0.0001 A1.21 S-0.57 (Knox, 1987)V = 0.065 d0.5 (Williams, 1983)Vc = 0.18 d0.44 (Koster, 1978)Vc = 0.18 d0.49 (Costa, 1983)Q1.5 =0.011 Lm

1.54 (Williams, 1983)λm = 166 Qm

0.46 (Carlston, 1965)τ = 0.030 d1.49 (Williams, 1983)

τ = 0.17 d (Williams, 1983)

ω = 0.079 d1.29 (Williams, 1983)

Symbols (Williams,

1984)

A = intermediate axis of largest clasts, mmd = particle diameter, mmD = competent flow depth, mλm = meander wavelength, mQ1.5 = discharge of 1.5 yr flood, m3/sQm = mean annual discharge, m3/s S = energy slope (approx. = topo. gradient), m/mV = mean flow velocity, m/sVc = threshold (critical) flow velocity, m/s

τc = threshold (critical) tractive force, N/m

τ = bed shear stress, N/mω = stream power/m of width, watts/m2

Floods & Quaternary Stratigraphy

Arid Streams (Most Sensitive: Most Studied)“Pluvials” Wet Episodes (≈ “Glacials”)Vegetation Cover Critical

Holocene Arroyo-Cutting and FillingUnder Drought:Hyper-Arid: Loss of Channel VegetationPromotes Erosion of Channel

Semi-Arid: Loss of Slope VegetationPromotes Erosion of Slopes + Filling of Channels

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http://geochange.er.usgs.gov/sw/impacts/geology/arroyos/

The Arroyo Problem in the Southwestern

United States

Brandon J. VogtU.S. Geological Survey

Tucson 1940

Note Rock

Tucson 1982

Note Rock

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Tucson 1940, 1982 Images From Landscape Changes in the Southwestern United States: Techniques, Long-term Data Sets, and Trendsby Craig D. Allen, Julio L. Betancourt, & Thomas W. SwetnaminSisk, T.D., editor. 1998. Perspectives on the land use history of North America: a context for understanding our changing environment. U.S. Geological Survey, Biological Resources Division, Biological Science Report USGS/BRD/BSR 1998-0003 (Revised September 1999). 104 p.

http://biology.usgs.gov/luhna/chap9.html

Precipitation Style & Floods

Convectional Thunderstorms: Favored by Hot Air Masses (Drought?)

Hurricanes: Favored by Warm SST & ITC North of Equator. Requirements Not Met in No. Hemisphere During “Glacials”

Frontal Precip: Driven By Energy of System (Increases w/ Warmer Oceans), But Circulation Pattern Is Locally More Important

Snow-Melt: Favored by Longer Winters, but Not If It Gets Too Cold (= Too Dry)

Floods & Quaternary Stratigraphy in Eastern USConvectional Thunderstorms: Favor Debris

Flows, Erosion of Gullies & Small Channels; Inefficient Middle to Large Streams

Hurricanes: Favor Debris Flows, Efficient Sed Transport on Small to Middle Streams

Frontal Precip: Efficient Sed Transport in Middle to Large Streams. Low Rainfall Intensity Limits Sediment Delivery by Small Streams

Snow-Melt: Freeze-Thaw Produces Lots of Sediment on Slopes, Inefficient Transport by Small Streams, Erosion by Large Rivers

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Quaternary Fluvial Stratigraphy in Eastern US

Complicated by Base-Level Fluctuations

Sea-Level Changes (Drop w/ Glaciation) e.g. Unglaciated Potomac, James basins

Local Basel Level (Rise w/ Outwash Aggradation) e.g. Glaciated Ohio, Allegheny River & Tribs

Quaternary Fluvial Stratigraphy in Eastern US

Where & When Are Base-Level Fluctuations More Important Than Climate-Driven Sediment Supply?

Unglaciated Rivers in Ohio River Basin (Kanawha, Mon, etc.):Ohio River Outwash Aggradation vs. Upland Sediment Flux (Local Slopes + Tribs)