fig7thum.jpg (79078 bytes)Figure 8. Sidescan-sonar images across two areas interpreted to be gravel patches north of Grays Harbor. The example in (A) suggests that the high-backscatter gravel patch occurs in a subtle bathymetric depression on the corresponding seismic-reflection profile. The example in (B) shows that the high-backscatter patches occur both above and away from paleo-river valleys that were cut during the last lowstand of sea level. Bottom photographs show that the low-backscatter areas have a surficial veneer of rippled fine sand while the high-backscatter areas show the presence of gravel. Click on the figure to view a larger image. Figure location shown in Fig.4.

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