Surficial geology interpretive map from the inner continental shelf off the northern Oregon and southern Washington coast based on sidescan-sonar imagery and sediment samples

Two 21-day field operations were conducted in 1997 and 1998 in the estuaries and on the inner continental shelf off the northern Oregon and southern Washington coast. These cruises aboard the R/V Corliss were run in order to generate reconnaissance maps of the seafloor geology and the shallow subsurface stratigraphy using sidescan-sonar and seismic-reflection mapping techniques. The 1998 cruise also collected sediment grab samples, bottom photographs, and video images to verify the sidescan-sonar imagery and to document the seafloor geology. The combination of these data with previously collected sediment sample data (Robert, 1974; Nittrouer, 1978; and Smith et. al., 1980) has been used to define the extent and lithology of shelf sediments associated with the Columbia River littoral cell. This work is one component of a larger project studying the erosion of the Washington Oregon coasts and is being coordinated by the U.S. Geological Survey and the Washington State Department of Ecology. The reasons for collecting these data are to provide a regional synthesis of the offshore geology for this project and to support a wide variety of management decisions and to provide a basis for further process-oriented investigations.

1997年与1998年，研究团队在俄勒冈州北部及华盛顿州南部沿岸外的河口区域与内陆陆架海域，开展两次为期21天的野外作业。本次航次由R/V Corliss号科考船执行，旨在借助侧扫声呐（sidescan-sonar）与地震反射测绘（seismic-reflection mapping）技术，绘制海底地质与浅地下地层的勘察测绘图。1998年的航次还额外采集了抓斗沉积物样品（sediment grab samples）、海底摄影照片与视频影像，用于验证侧扫声呐成像结果并记录海底地质特征。将本次采集数据与此前已获取的沉积物样品数据（Robert, 1974; Nittrouer, 1978; Smith et al., 1980）相结合，可明确与哥伦比亚河沿岸输沙单元（Columbia River littoral cell）相关的陆架沉积物分布范围与岩性（lithology）。本研究是华盛顿州与俄勒冈州海岸侵蚀大型研究项目的子课题之一，由美国地质调查局（U.S. Geological Survey）与华盛顿州生态部（Washington State Department of Ecology）统筹协调。本次数据采集工作的核心目标，在于为该项目提供近海地质的区域综合研究成果，支撑各类管理决策，并为后续面向过程的专项研究提供基础依据。