Geology of Vancouver Lake, Washington, “Bulls Eye” Lake

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By: Candice Armijo and Curt Peterson

Questions

How old is Vancouver Lake?

How was the shape of the lake formed?

How did the water accumulate in the lake?

Did the water get trapped inside this form?

What We Know AboutVancouver Lake

Surface area of lake: ~9km2

Depth of lake:

~1 to 4 meters

Has been classified as a short-lived ‘ephemeral’ lake.

West Side of lake

West side of lake

Bottom of Scroll bar

NW Side of Lake

Core Crvl-07

Ash Layer

Columbia River Moving to the West

Mud (%)90.99

Mud (%)13.4

Mud (%)78

Mud (%)88.3

Mud (%)89.3

Sand (%)9.01

Sand (%)86.6

Sand (%)22

Sand (%)11.7

Sand (%)10.7

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

CRVL‐02 (1.3m)

CRVL‐03(0m)

CRVL‐07 (0m)

CRVL‐07 (4m)

CRVL‐08 (1.8m)

Sieve analysis

Cross Section

CRVL-02CRVL-03

CRVL-08CRVL-07

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SW NE

core CRVL-07

Sandy mud

Mud

Sandy mud

Mud

Peaty mud

Ash

Peaty mud

Sediment movement

Lake sediments

Sediment movement

Lake sedimentsHolocene Sea Level Rise

Floodplain

Ash - Mt. St. Helen’s Eruption Set-P ~2,500-3,000 yr BP

Floodplain

Samples taken for Radiocarbon Dating

‘Bulls Eye’ Lake

Vancouver Lake was formed by the submergence of an ellipsoidal vegetated flood plain basin that was previously formed by successive but oppositely directed channel migrations, i.e., oppositely orientated scroll bars. The Bulls Eye Lake or Bulls Eye Pond is maintained indefinitely when the rate of submergence from sea level rise exceeds the rate of sedimentation in the stable flood plain basin.

Bower Slough

Conclusion Represent a new classification of flood plain features which are likely unique to large-scale fluvial-tidal settings.

Bachelor Island Sauvie Island Deer Island

Radiocarbon dates are pending: Beta Analysis Inc. (Summer 2012)

CoAuthours

Davidshofer, Charles J. Eslinger, Thomas E. Friedman, Corey J. Gallagher, Sean M. Gardner, Ashley L. Gibson, Matthew G. Handrich, Tracy E. Jenkins, Emily Kho, Paulina Large, Adam M.

Misak, Nicholas M. Osilla, Jade Catherine P. Paetsch, Jacob W. Pontifex, Molly K. Priddle, Shawn C. Shafer, Erik P. Shields, Harold E. Slaughter, Brian Stata, Eric R. Sunnarborg, Justin M.

Sourceswww.co.clark.wa.us/waterresources/documents/Monitoring/VanLakewww.ci.vancouver.wa.us/publicworks/vancouverlake/MapsMaterials/vlwp_mapsandmaterials.htmC.D. Peterson, 2011 Geomorphologywww.wlsevier.com Shannon and Wilson, Inc., 1972, Portland Or., Vancouver Lake Urban Planning Project Port of Vancouver, Wa.