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Description
The discovery survey of Astoria Canyon off the Oregon coast. The lines of dotsare lines of soundings navigated by means of radio-acoustic ranging, the firstprecision navigation system to eliminate the need for visual signals. Thissystem was developed by the C&GS; in the 1920's and used until WWII. Manydiscoveries were made because of it. (Image credit: NOAA Central Library Historical Collection)