Archive of Boomer seismic reflection data collected aboard RV CORLISS cruise CRLS97007 off northern Oregon and southern Washington inner continental shelf

A 21-day field operation was conducted on the inner and middle continental shelf off the northern Oregon and southern Washington coast during which approximately 1200 line km of seismic-reflection, sidescan-sonar, and bathymetric data were acquired to generate reconnaissance maps of the seafloor geology and the shallow subsurface stratigraphy of this shelf environment. The Columbia River has provided huge amounts of sediment to this shelf during the Holocene transgression. Previous studies have mapped the distribution and thickness of this modern deposit on the middle and outer shelf (Nittrauer, 1978; Wolf and others, 1997), however, the distribution of this deposit on the inner shelf and its link to the adjacent coastal environment were not as clearly understood because of incomplete data coverage on the innermost shelf. Although sidescan-sonar imagery has been collected off the mouth of the Columbia River, no reconnaissance coverage was available for the entire area. Additionally, the most recent bathymetric survey of this area was completed during the 1920s (National Ocean Service, 1983). Anthropogenic activity within the Columbia River drainage basin (agriculture, logging, construction of dams, and dredging of the estuary mouth) may have altered the sediment discharge from the river which, in turn, may be affecting sediment distribution on the shelf and in adjacent coastal environments. The seismic-reflection data in concert with sidescan-sonar imagery and bathymetry collected along the same survey lines will provide an overall synthesis of the sea floor environment including the Holocene stratal geometry, the distribution of different sediment types, the distribution of mobile bedforms, outcrops of Pleistocene and older strata, and the locations of faults. The goal of this project is to provide a regional synthesis of the offshore geology to support a wide variety of management decisions and to provide a basis for further process-oriented investigations. The project is conducted cooperatively with the Washington State Department of Ecology.