Velero IV bucket dredge operation, [1950s?]

"Velero IV footage". Seafloor sample collector (OP bucket) is lifted from water aboard the Velero IV (ship), claw on bottom of collector opens to deposit mud sample into large bucket, men shovel samples of bottom sample out of large bucket onto sorting table, the sample contains marine specimens such as mollusks and worms and slugs and starfish, close-ups of stern winch operation and derrick, view of port side of Velero IV from on the water "U.S.C. Marine Laboratory", rinsing the mud sample in vibrating tray (shaker table), close-ups of rinsed sample, the man in the black cap is Fred C. Ziesenhenne, [1950s?]. The film was received from Dr. Tibby, 1961 December 1. A note with the film calls it "oceanography film" and mentions "Churchill-Wexler Films, educational and industrial".