Use of radiocarbon dating and tree ring analysis to study a submerged forest in Lake Kapowsin, Washington Jordan Conner, Danielle Z’berg, and Patrick Pringle,  Centralia  College  WA  

Abstract Along with three scuba divers, we investigated a submerged subfossil forest in Lake Kapowsin near Electron, Washington. Two of the submerged trees were cored by scuba diver Danielle Z’berg. Additionally, we took samples by kayak from the tops of the trees located just inches below the water and recorded the GPS locations of selected stumps (Fig. 1). Because we wanted to test the hypothesis that the lake was created when the Electron Mudflow from Mount Rainier blocked Kapowsin Creek about 1500 CE, we selected wood from rings in the cores that would yield the least amount of error when lab results were calibrated with the radiocarbon decay curve (Fig. 2). The cores were polished and mounted so that they could be measured and compared to previous samples taken from trees buried near Orting, Washington and with master tree-ring chronologies in the region. Introduction Geologists have interpreted that Lake Kapowsin is dammed by the Electron Mudflow from Mount Rainier (Crandell 1963). The Electron Mudflow was a large volcanic debris flow, or lahar, which flowed along the Puyallup River about AD 1500 (Fig. 3)(Crandell, 1963; Vallance and Pringle, 2008). The age of the Electron Mudflow comes from analysis of buried trees near Electron and Orting, Washington, however, the trees in Lake Kapowsin have never been radiocarbon dated to confirm that the lake is dammed by the Electron Mudflow or by one of the several previous lahars that flowed along the Puyallup River (Fig. 1).

Lake Kapowsin is being proposed as an Aquatic Preserve, and so a technical committee has been established by the Washington Department of Natural Resources (WADNR) to study the lake. Therefore, we sought to obtain a radiocarbon age on the subfossil trees within the lake that would provide more information confirming the lake’s age and origin. Obtaining core and saw-cut samples of the trees for tree-ring analysis would be particularly useful because previous tree-ring work on Lake Kapowsin was on trees that had been recovered from the lake by floating barge, so the origin of the wood is uncertain.

 

Figure 3. Map from Pringle (2008) showing pathways of past clay-rich lahars (volcanic mudflows) from Mount Rainier during the past 6000 years including the ~1500 CE Electron Mudflow, which has been interpreted to have blocked Kapowsin Creek to create Lake Kapowsin. Map adapted from Crandell, (1971).

 

Figure 4. diagram showing the distribution and thickness of the Electron Mudflow. After Crandell (1963).

 

Geology of the Area Lake Kapowsin lies south of the hamlet of Electron and to the west of Mount Rainier. Crandell (1963) states that the formation of this lake was brought on by the Electron Mudflow when approximately 30 feet of rock and mud debris dammed up Kapowsin Creek (Fig. 4). The mudflow may been caused by a possible eruption or explosion of Mount Rainier volcano, which led to the collapse of its upper west flank that consisted of abundant hydrothermally altered rock. Remains of this clay-rich and andesitic mudflow stretch from Electron to Sumner and can be identified at various places along the Puyallup River Valley between Electron and Rainier.

 Methods Because of the interpretation Lake Kapowsin is dammed by the deposits of the Electron Mudflow, we examined the radiocarbon decay curve recently updated by Reimer and others (2013) in order to find the time interval that would yield the least amount of error (steepest part of the curve) after calibration for trees that died about 1500 CE. We selected a three-ring sample from the pith of core 14a, about 60 rings from the outmost wood of the tree. The sample was dried, wrapped in foil, and sent to Direct AMS in Bothell, Washington. Before processing, the cores taken by diver Danielle Z’berg (Z’berg and others, this volume), were straightened, placed on a mount, and polished with abrasive paper, starting with 100 grit and working up to 2000 grit. They were then cleaned and scanned on an Epson 10000XL scanner at 2400 DPI (0.01 mm precision). The cores include one western hemlock (Tsugaheterophylla) and one Douglas-fir (Pseudotsuga menziesii). We used ImageJ image analysis software to measure the rings from the scanof the Douglas-fir core, which had the highest number of rings, 429 (Fig. 5). Together we reviewed the measured scans for accuracy and made a few small adjustments to a couple of measurements. After that, we compared our measurements with those made by Centralia College Student Rebeca Becerra (now student at Central Washington University) made in 2014 on samples from the lake in 1989. Those samples had been taken by Patrick Pringle from trees that had been removed from the lake during a logging operation,and thus the age of the samples is uncertain. We attempted to cross date individual time series of each sample’s ring widths with the aid of Cofecha software (Holmes 1983; Grissino-Mayer, 2001) for the previous and current measurements.

References Clark, E. E., 1953, Indian Legends of the Pacific Northwest. University of California Press [Berkeley], 225 p. Crandell, D. R., 1963, Surficial geology and geomorphology of the Lake Tapps quadrangle, Washington: U.S. Geological Survey Professional Paper 388-A, 84 p., 2 plates. [accessedfrom http://pubs.er.usgs.gov/usgspubs/pp/pp388A] Crandell, D. R., 1971, Postglacial lahars from Mount Rainier volcano, Washington: U.S. Geological Survey Professional Paper 677, 75 p., 3 plates. [accessedfrom http://vulcan.wr.usgs.gov/Volcanoes/Rainier/Publications/PP677/framework.html] Grissino-Mayer, H.D., 2001. Evaluating crossdating accuracy: a manual and tutorial for the computer program cofecha: Tree-Ring Research, v. 57, p. 205-221. Holmes, RL, 1983. Computer-assisted quality control in tree-ring dating and measurement. Tree-Ring Bulletin, v. 43: p. 69-78. Pringle, Patrick T., 2008, Roadside geology of Mount Rainier National Park and vicinity: Washington Division of Geology and Earth Resources Information Circular 107, 191 p. [Accessed on June 3, 2008 at http://www.dnr.wa.gov/ResearchScience/Topics/GeologyPublicationsLibrary/Pages/pub_ic107.aspx] Pringle, Patrick T., 2008, Roadside geology of Mount Rainier National Park and vicinity: Washington Division of Geology and Earth Resources Information Circular 107, 191 p. [Accessed on June 22, 2008 at http://www.dnr.wa.gov/ResearchScience/Topics/GeologyPublicationsLibrary/Pages/pub_ic107.aspx ] Pringle, Patrick, 2014, Buried and submerged forests of Oregon and Washington: time capsules of environmental and geologic history: Western Forester, v. 59, no. 2, p. 14–15, 22. [Accessed on May 5, 2014 at http://www.forestry.org/northwest/westernforester/2014/ (entire issue); or download this article alone via http://www.centralia.edu/academics/earthscience/pubs/pringle_buried_forests_WF_March_April_May_2014pp14-15-22.pdf ] Reimer P.J., Bard E., Bayliss A., Beck J.W., Blackwell P.G., Bronk Ramsey C., Buck C.E., Cheng H., Edwards R.L., Friedrich M., Grootes P.M., Guilderson T.P., Haflidason H., Hajdas I., Hatt A.C., Heaton T.J., Hogg A.G., Hughen K.A., Kaiser K.F., Kromer B., Manning S.W., Niu M., Reimer R.W., Richards D.A., Scott E.M., Southon J.R., Turney C.S.M., van der Plicht J., 2013, IntCal13 and MARINE13 radiocarbon age calibration curves 0–50000 years cal B.P.: Radiocarbon 55(4). DOI: 10.2458/azu_js_rc.55.16947 Scott, K. M.; Vallance, J. W.; Pringle, P. T., 1995. "Sedimentology, Behavior, and Hazards of Debris Flows at Mount Rainier, Washington." U.S. Geological Survey Professional Paper 1547, 56 p., 1 plate. http://pubs.er.usgs.gov/usgspubs/pp/pp1547 Steer, James, H., 2010, Fundamentals of tree ring research: The University of Arizona Press, Tucson, Arizona, p. 368. Stokes, Marvin A.; Smiley, Terah L., 1968, An introduction to tree-ring dating: University of Arizona Press, 73 p. Vallance, J. W.; Pringle, P. T., 2008, Lahars, tephra, and buried forests—The postglacial history of Mount Rainier, In Pringle, Patrick T., 2008, Roadside geology of Mount Rainier National Park and vicinity: Washington Division of Geology and Earth Resources Information Circular 107, 191 p. [URL: http://www.dnr.wa.gov/ResearchScience/Topics/GeologyPublicationsLibrary/Pages/pub_ic107.aspx ] Wolcott, Ernest E., 1973, Lakes of Washington; Volume I--Western Washington; 3rd ed.: Washington Division of Water Resources Water-Supply Bulletin 14, 619 p. [accessed May 31, 2012 at http://www.ecy.wa.gov/programs/eap/wsb/wsb_All.html] CITATION: Conner,  Jordan,  Z’berg,  Danielle,  Pringle,  Patrick,  2015,  Use  of  radiocarbon  da?ng  and  tree-­‐ring  analysis  to  study  a  submerged  forest  in  Lake  Kapowsin  WA,  3rd  Annual  Centralia  College  Capstone    Project  Presenta?ons,  p.  5.  [Download  poster  at  hMp://www.centralia.edu/academics/earthscience/pubs/conner_etal_lake_kapowsin_capstone2015.pdf  ]  

 

Further Research More samples from Lake Kapowsin could be gathered in order to increase the sample size and therefore increase the chances of finding rings within different cores that correlate. The results of the radiocarbon dating for the innermost rings that were sent to the DirectAMS lab were not received in time to be analyzed prior to publication, and could therefore be used in future research on the lake. Furthermore, the Lake Kapowsin cores could be compared to samples of other subfossil trees previously exhumed from the Electron Mudflow near Orting, Washington to see if there are any correlations. Also, other lakes in Washington could be studied using similar methods in order to determine how they came to be.

Figure    5.  Screenshot  showing  annual  growth  rings  of  one  of  the  tree  samples  from  Lake  Kapowsin  with  ImageJ  image  analysis  soUware.  

 

Discussion Cofecha matched core 15a (the Douglas-fir sample) with core 5b from the 1989 sample selection. It stated that there was a possible overlap of 121 rings; the overlap for the 5b core ended one ring away from its outermost end, while the overlap for the 15a core ended rings away from its outermost end. The samples had a correlation coefficient of 0.26, which reports that the cores have some positive linear relation. However, this could be anomalous due to the fact that our sample size was limited to two cores.

Figure 1. Submerged stumps in Lake Kapowsin have been eroded to slightly below the water line.

Calibrated  Age  

Raw  Age                        500  

Acknowledgements Special thanks to scuba divers Danielle Z’berg, Bert Brezicha, and George Potts for coring the submerged stumps. The lead author thanks the Centralia College Foundation for a Capstone Research Grant for the funding of the radiocarbon analysis.

 

Figure 2. Left, sample to be dated was selected based on this calibrated graph and the age of the Electron Mudflow by Vallance and Pringle (2008).

Or?ng  “big  stump”  ~1500  ±10  cal  yr  BP  

target  steep  zone  of  decay  curve  for  wood  sample