U.S. Geological Survey Open-File Report 2009-1101
The Partition Intervalometer: A Programmable Underwater Timer for Marking Accumulated Sediment Profiles Collected in Anderson Sediment Traps: Development, Operation, Testing Procedures, and Field Results
Hueneme Canyon Site — Mooring 838, Water Depth 190 m
Upper trap – 60 mab – (Intervalometer 4): programmed at 09:30 (local time) on 9-11-07 with a 10-day drop interval, trap overfilled with sediment, all discs/washers deployed, 16 discs indicating approximately 160 days of sediment accumulation in the filled collection tube. Remaining discs and washers were recovered from the cone portion of the sediment trap.
Lower trap – 30 mab – (Intervalometer 5): programmed at 10:05 on 9-11-07 and a 10-day drop interval, trap overfilled with sediment, collection tube filled with sediment with 11 discs indicating 110 days of continuous sediment accumulation throughout the entire length of the collection tube. A malfunction occurred after disc 11 was deposited probably as a result of a disc jam and perhaps resulting in a motor failure. Remaining discs and washers were randomly located in the cone area of the sediment trap and in the manifold of the intervalometer.
The sediments collected from both sediment traps were primarily muddy in nature and contained alternating bands of black-colored anoxic sediments as well as irregular fine- and coarse-grained material throughout the core.
Mugu Canyon Site — Mooring 839, Water Depth 190 m
Upper trap – approximately 100 mab – (Intervalometer 1): initialized at 08:56 on 9-11-07, only about 2.5 cm of sediment accumulated in the collection tube because disc 1 blocked the sediment-trap opening to the collection tube. However, all the discs and washers were released from the manifold and were scattered throughout the sediment collected in the cone above the collection tube.
Mid-level trap – 60 mab – (Intervalometer 2): programmed at 09:10 on 9-11-07, 17 discs and 2 washers were deposited into the collection tube with no evidence of overfilling of sediment above the collection tube. This would indicate at least 190 days of continuous sediment accumulation as defined by the (marker) disc placement in the tube.
Lower trap – 30 mab – (Intervalometer 3): the 10-day disc drop interval was preset at 09:42 on 9-11-07, the trap overfilled with sediment, 16 discs were found in the collection tube, disc 17 was lost but the remaining disc (18) and the two washers were found in the overlying sediment accumulated in the sediment-trap cone above the collection tube.
This would indicate that approximately 160 days of sediment amassed in the collection tube.
Similarly, the sediments collected from both traps were muddy, displayed several areas of alternating coarse- and fine-grained material throughout the cores, and revealed the possible presence of anoxic sediments with associated black-banding coloration through several segments of the core.