Post on 15-Mar-2018
transcript
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.
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
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.