The sound film of "The North Pacific Crossing" is one of a Series produced by Teledyne Exploration Co. presenting the high power sparker profiles taken aboard the M/V Stranger during her circumnavigation of the earth. Over a thousand miles of subbottom seismic profiles are shown, beginning with the departure from Kyushu, Japan. Portions of the typical records are shown from the Shikoku Basin, Japan Trench, the mid-Pacific sea mountains, Hawaiian Platform and the Abyssal Hills Province between Hawaii and San Diego, the end of the cruise.
The Motor Vessel Stranger left the Japanese island of Kyushu at midnight on Christmas Eve, 1968, with one more ocean crossing to complete her round-the-world passage. The North Pacific crossing via Wake Island and Honolulu to-San Diego was to log over 5,000 miles, ending on Feb. 12. The Stranger's average speed was 8 knots.
Close to Kyushu the sea floor is rough. The sediments are thin except where down-faulted blocks have trapped them. The Shikoku Basin begins close to the land and within a few hours of her departure the Stranger is profiling the bottom at depths of 10,000 ft. As the record continues into deeper water, the time for sound echoes to return to the ship increases. The travel time labels on the charts show when a shift is made at the recorder to keep the subbottom record on the paper.
At the bottom of the Shikoku Basin the water is 15,000 ft deep. The uniform layered rocks of Oligocene and Eocene age rise slowly to the east.
Most of the layered rocks far from shore are believed to be of volcanic origin. The fluid lavas apparently flowed out over many tens of thousands of square miles of the Pacific sea floor. A veneer of deep sea sedimentary oozes covers the bottom and helps to smooth it.
North of Iwo Jima among the Bonin Islands a group of submarine volcanoes rise abruptly from the basin floor. The flanks of the mountains are partly covered with wedge-shaped aprons of volcanic ash, lava and perhaps sediments derived from the erosion of the mountain rock. Where the volcanoes are close together several thousand feet of layered rocks are trapped between them.
The Stranger is now 120 miles west of the Japan Trench and sailing eastward. The slope toward the trench is at first gradual. Thick layered sections are trapped behind ridges in the basement rocks. There is nothing Visible yet to forecast the spectacular downbuckle of the sea floor a few miles to the east.
On portions of the slope the subbottom rocks are composed of large overlapping lens shaped structures. These are apparently depositional features produced by cyclic changes in the supply of sediments. They are remarkably similar in appearance to the fore-set lenses of delta sediments, but here occur at depths below 13,000 ft.
