CGRG Bibliography of Canadian Geomorphology
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Author : Enkin, R.J.; Chang, A.S.; Dallimore, A.; Baker, J.; and Thomson, R.E.
Date : 2006.
Title : Weather, climate and seismicity recorded in 1KA-present freeze cores; results from Effingham Inlet.
Publication : North Pacific Climate Workshop. Canadian Institute of Ocean Sciences, Sidney, British Columbia, Canada. March 1 to 3, 2006.
Issue :
Page(s) :
Abstract
Freeze cores of recent sediments were recovered from the anoxic inner basin of Effingham Inlet (49°04.218' N, 125°09.429' W), British Columbia. The chronology of the top of the cores was established by varve counting, 137Cs dating and 210Pb dating. These varves are dated from AD 1947 to 1997 above an ~85-cm thick landslide deposit interpreted to have been caused by the M=7.3, June 1946 Comox earthquake. Varve thickness and the thickness of individual detrital and diatomaceous laminae were examined from X-ray photographs of the sediments. The thickness, density, and temporal structure of the dark winter detrital laminae correlate to regional rainfall records (daily and monthly). The dominant diatom species, Skeletonema costatum, blooms in the late spring. Comparison of varve thickness and brightness to upwelling indices based on the strength of northwest winds during the months of May and June each year and reveal a weakly positive correlation. The lower parts of the freeze cores are dated by varve counting and 14C dating. Earthquake-generated mass wasting events are recognized at AD 1700 and 1300. Other massive horizons (“homogenites”) are interpreted to be caused by bottom-hugging upwelling currents following large rainfall. Above one of these horizons, a layer of fish skeletons suggests the displaced anoxic water killed the school. A transition from thin varves and numerous homogenites to thick varves at 105cm depth could be related to regime change at the end of the Little Ice Age (~AD 1850).
Bibliography of Canadian Geomorphology