U. S. Geological Survey Open-File Report 01-154
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U. S. Geological Survey Open-File Report 01-154 |
Cruise Report - DSRV ALVIN 269 |
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PURPOSE: |
To sample rock ledges from isolated banks and ledges in the Gulf of Maine. |
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DATES: |
May 20 (1130) to 28 (0530), 1968 |
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SHIPS: |
R/V GOSNOLD (Cruise
#118) |
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SCIENTIFIC PARTY: |
John S. Schlee, USGS, Chief
Scientist |
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CRUISE NARRATION: |
Departed Woods Hole at 1130 May 20th on R/V GOSNOLD for Gulf of Maine, via the Cape Cod Canal. DSRV LULU remained a day In Woods Hole while its gyroscope settled down after an early morning "tumble". Arrived off Race Point light at 1728, and dredged the southern end of Stellwagen Bank at 1800 (Station 2717) and near Wildcat Knoll at 2030 (Station 2818). The first station was mainly sand dollars and scallop shells; the second station was benthonic fauna of Cerianthus tubes, brachiopods and pink sea anemone. A final dredge was made west of Wildcat Knoll (Station 2719) at 2230 and obtained glacial pebbles plus clam shells, crabs, anemones, and gastropods. During the remainder of the night we proceeded toward north end of Stellwagen Bank. At 0815 on May 21st we dredged the northern end of the Bank near Tillies Basin. The dredge (Station 2720) brought up clamshells, Cerianthus tubes, starfish and one rafted pebble with attached sponge. The GOSNOLD proceeded northward toward the southern end of Jeffreys Ledge and made 3 dredge stations, 2 east of Scantum Basin (Stations 2721, 2722) and one on the east side of Jeffreys Ledge (Station 2723). They yielded mainly, glacial cobbles plus Cerianthus tubes, shell debris, echinoids, and sponges. Similar material on northern part of the ledge (Station 2724) was obtained In the early evening, after which we ran an echo sounding profile out into northwestern Wilkinson Basin along a triangular course track from 2000 to 2340. At 0600 on May 22nd, Schlee transferred over to LULU (which had come up to Jeffrey Ledge from Woods Hole the day previous, to make ALVIN dive 268 (See Dive narrations). Hathaway and Hayes remained aboard GOSNOLD and made a rectangular traverse of Jeffreys Basin for echosounding profiles. They arrived back at Jeffrey Ledge about 1230, to rendevoux with LULU. Hathaway transferred to LULU at 1300 and Schlee returned to GOSNOLD at 1630 from LULU following termination of dive. The armada moved over to Platts Bank on the late afternoon and evening of the 22nd. Both vessels anchored on Platts Bank for the night and on the morning of May 23rd a marker buoy was anchored on the bank by GOSNOLD, At 1048 GOSNOLD hauled its anchor, to commence occupying a series of dredge stations on Platts Bank. Moderate fog forced cancellation of an Intended AL71ZI dive; further, breakdown of a" refrigerator motor forced LULU to head for Portland, Maine, about 40 miles distant. During the remainder of that day five dredgings (Station 2725-29) were made on the bank to recover bedrock Though the chain bag dredge caught on several large rocks, no freshly broken fragments were evident in the dredge hauls. They were glacial cobbles up to 256 mm of widely varying lithologies, plus sponges, Cerianthus tubes, orange starfish, scallop shells, brachiopods, and anemones. Following the last dredge haul at 1910, we anchored for the night near the buoy. The morning of May 24th we weighed anchor and dredged the crest of Three Dory Ridge (Station 2730) and made echo sounding traverses southeast of Three Dory Ridge across Blacks Basin, Blacks Ridge, and back to Platts Bank. Additional dredgings were made on the Bank and a knoll south of it (Station 2731, 2732); like the other ones the dredge recovered mainly glacial debris along with sessile benthic fauna and one goose fish. Following the last dredge haul at 1720, we headed out for an echo sounding traverse on a triangular course for northeastern Wilkinson Basin, arriving back at Platts Bank at 2230. LULU also arrived back on the Bank the afternoon of the 24th, preparatory to diving the next day. May 25th was calm and hazy. While ALVIN with Hathaway aboard dove on the southeast side of the Platts Bank, Schlee and Hayes echo sounded over Platts Basin north of the Bank, leaving at 0930 and arriving back by the buoy at 1645. The buoy was picked up by crew of the GOSNOLD at 1700 and Schlee went over to the LULU at 1740, to prepare for a dive on May 26th. Both vessels cruised over to Three Dory Ridge early the morning of May 26th and crew of the GOSNOLD set the buoy on the flank of the ridge. Then the GOSNOLD went on a triangular course track for echo sounding profiles of eastern Platts Basin while Schlee dove in ALVIN. A sudden storm came up about 1100 with winds gusting to 40 knots out of the east. The dive was abruptly terminated at 1110 due to rough seas. GOSNOLD returned to Three Dory Ridge and stood by during afternoon. It retrieved the buoy at 1800. That evening both vessels cruised to Platts Bank and anchored for the night. Hathaway transferred back to LULU in preparation for a dive the next day. The next morning (May 27th) though the sea was calmer, conditions were marginal for surface handing of ALVIN. We cruised southwestward toward Wildcat Knoll, and though the sea continued to abate, further dives were not scheduled because a storm was forecast for the evening of the 27th. Hayes made echo sounding profiles across Wilkinson Basin from 0725 to 1700 as GOSNOLD moved toward Cape Cod Bay. The canal was entered at 2100. GOSNOLD anchored in Buzzard Bay for the night, docking at Woods Hole at 0635, May 28th. LULU cruised slowly for Woods Hole during the night and arrived there at 0530.
The dive commenced at 0905. Bottom was reached at 0935 in 100m depth. Visibility was about 25 feet. The bottom was fine sand and some silt, but showed no ripple marks. The bottom was underlain by hard rock at a depth of 6 to 8 in. Numerous Cerianthus tubes, sponges, and some sea anemones but very few fish were observed. Only scattered cobbles or small boulders were seen. Proceeded up the southeast slope of Platts Bank which reach an inclination of about 12 degrees and encountered currents of about 0.8-1.0 knots from the North. The top of the bank was reached at a depth of 75 meters. Near the edge there were few ripple marks, only a slight mottling of the bottom. The ambient light was strong enough for viewing without the submarine lights. More ripple marks were observed as the top of the bank was traversed. Most of these were aligned North-South and reached a wave length of 2-3 feet with amplitudes of about 6 in. Scattered boulder and cobble fields were traversed. Some boulders were up to about 20 feet in diameter. Fewer Cerianthus tubes but more sponges occurred on top of the bank than on the flanks of the bank. Relatively few fish were observed; these were principally cod and some haddock. No halibut, fluke, flounder, shrimp, lobsters, or crabs were seen. Very few scallops or clams, or gastropod shells were seen. Fish of which one or two specimens were observed were eel, cusk, dogfish, and sculpin. A sonar echo which was pursued but never reached because of its rapid change of position was probably a large school of fish, perhaps cod. No outcrops of sedimentary rock were observed; of the four samples that were collected, one was a core of sand from the base of the bank slope and three were glacial erratics, two granites and one gneiss from the top of the bank. Two rolls of E. G. & G., one black and white, one color; 400 feet of Eclair movies, 200 feet Bell & Howell movies, 1 1/2 roll-3 of Stereo Realist and 1 roll Nikkormat, all color, were taken, during the dive. The dive was terminated because of low propulsion - battery voltage and the submarine surfaced at 1530. |
