Gully annealing by aeolian sediment: Field 

and remote-sensing investigation in Glen, 

Marble, and Grand Canyons

Joel Sankey1 (jsankey@usgs.gov)

Amy Draut2, Helen Fairley1, Brian Collins3, Dave Bedford3

1 US Geological Survey, Grand Canyon Monitoring and Research Center

2 US Geological Survey, Pacific Coastal and Marine Science Center

3 US Geological Survey, Geology Minerals Energy and Geophysics Science Center

Annual Reporting Meeting

Phoenix, AZ, January 28 & 29, 2014

U.S. Department of the Interior

U.S. Geological Survey
Fluvial-aeolian-hillslope (upland) interactions

River

Wind
What happens to upland landscapes = 

what happens to archaeological sites

• Many archaeological sites 

are susceptible to gully 

incision

• Some archaeologically 

significant locations have 

very little active aeolian 

sand area, which might 

increase susceptibility to 

gully erosion
Aeolian sand in upland landscapes

• Possible that some yet-undocumented archaeological sites are within river-corridor 

dune fields

• Archaeological sites within dune fields might be less susceptible to gully development

Basalt: 27% active sand

• River corridor dune fields largely 

originated from ‘extreme’ floods

• HFE deposits often smaller, far 

away, blocked by riparian 

vegetation

• So, less connectivity between 

fluvial and upland landscapes 

today than in past

River

Wind

Wind
Comparing active vs. inactive aeolian sand

“Active” aeolian 

sand has windrippled surfaces, 

slip faces at 

angle of repose 

(Lancaster, 1994)

Active

“Inactive” Inactive

aeolian sand: 

biocrusted

without ripples 

(Draut, 2012)
Objectives for landscape scale analysis

Active

Are gullies more Inactive

prevalent in places 

like this?

Are gullies less 

prevalent and/or 

annealed (healed) 

in places like 

this?
Hypotheses

(1) Gullies are more evident in areas where sediment is inactive with 

respect to aeolian transport than in areas with active aeolian 

transport;

(2) Gullies terminate more commonly in active aeolian sand than in 

inactive sand;

(3) The historical (remotely sensed image) record contains evidence of 

gullies that have annealed over time and so are less evident today 

than in the past.
Methods – sand mapping

(Preliminary Data from Sankey and Draut, Do Not Cite)
Methods – gully delineation

• Goal

– Identify flow paths 

with concave acrossslope shape
Gully 

delineation

DEM

Flow

Accumulation

Topographic

Plan Convexity

Final Gully Map

(Preliminary Data 

from Sankey and 

Draut, Do Not Cite)
Forster

Fossil

(Preliminary Data from Sankey 

and Draut, Do Not Cite)
Results

How does the proportion of 

active vs. inactive aeolian 

sand vary by reach? 

How does the proportion of 

area affected by gullies vary 

by reach? 

(Preliminary Data 

from Sankey and 

Draut, Do Not Cite)
Results - hypothesis 1

Are gullies more evident in areas where sediment is inactive with respect to aeolian 

transport than in areas with active aeolian transport?

(Preliminary Data 

from Sankey and 

Draut, Do Not Cite)
Results - hypothesis 2

Do gullies terminate more commonly in active aeolian sand than in inactive sand?

(Preliminary Data 

from Sankey and 

Draut, Do Not Cite)
Results - hypothesis 3

Does the historical (remotely sensed image) record contain evidence of gullies that 

have annealed over time and so are less evident today than in the past?

(Preliminary Data 

from Sankey and 

Draut, Do Not Cite)
Connectivity along the river-hillslope continuum

 To what extent will:

 - decreased fluvial (HFE) deposition, and

 - increased riparian vegetation growth (barriers),

 inhibit aeolian sand supply inland? 

Future Questions