Sudden, probably coseismic submergence of Holocene trees and grass in coastal Washington State

Journal Article · Mon Jul 01 00:00:00 EDT 1991 · Geology; (United States)

DOI:https://doi.org/10.1130/0091-7613(1991)019<0706:SPCSOH>2.3.CO;2· OSTI ID:5996390

Atwater, B F ^[1]; Yamaguchi, D K ^[2]

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1. Univ. of Washington, Seattle (United States)
2. Univ. of Colorado, Boulder (United States)

Growth-position plant fossils in coastal Washington State imply a suddenness of Holocene submergence that is better explained coseismic lowering of the land than be decade- or century-long rise of the sea. These fossils include western red cedar and Sitka spruce whose death probably resulted from estuarine submergence close to 300 years ago. Rings in eroded, bark-free trunks of the red cedar show that growth remained normal within decades of death. Rings in buried, bark-bearing stumps of the spruce further show normal growth continuing until the year of death. Other growth-position fossils implying sudden submergence include the stems and leaves of salt-marsh grass entombed in tide-flat mud close to 300 years ago and roughly 1,700 and 3,100 years ago. The preservation of these stems and leaves shows that submergence and initial burial outpaced decomposition, which appears to take just a few years in modern salt marshes. In some places the stems and leaves close to 300 year old are surrounded by sand left by an extraordinary, landward-directed surge-probably a tsunami from a great thrust earthquake on the Cascadia subduction zone.

• OSTI ID: 5996390
• Journal Information: Geology; (United States), Vol. 19:7; ISSN 0091-7613
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
COASTAL REGIONS
GEOLOGIC HISTORY
GROUND SUBSIDENCE
WASHINGTON
DECOMPOSITION
EARTHQUAKES
ESTUARIES
FOSSILS
GEOLOGIC MODELS
GRAMINEAE
PLANT GROWTH
QUATERNARY PERIOD
SAND
STRATIGRAPHY
SUBDUCTION ZONES
TIME DEPENDENCE
TREES
TSUNAMIS
CENOZOIC ERA
CHEMICAL REACTIONS
DEVELOPED COUNTRIES
DISASTERS
FEDERAL REGION X
GEOLOGIC AGES
GEOLOGY
GRAVITY WAVES
GROWTH
LILIOPSIDA
MAGNOLIOPHYTA
NORTH AMERICA
PLANTS
SEISMIC EVENTS
SURFACE WATERS
USA
WATER WAVES
580000* - Geosciences