Bruce Heezen was one of the great oceangraphers of the 20th century. He discovered the Mid-Atlantic Ridge, the Hudson Submarine Canyon, ocean trenches, underwater volcanoes, and many other previously unknown features of the ocean floor. With Maric Tharp he published the first maps of the seafloor of each of the earth's oceans and later, the first map of the overall world ocean floor in 1977, the year that he died of heart failure in a submarine that was taking him to check additional seafloor features. He had been a classmate who shared desk space with me in the basement corridor of Columbia's Geology Department, and we were both graduate assistants to the legendary geophysicist Maurice Ewing, who was the first director of the Lamont Geological Observatory (now the Lamont-Doherty Earth Observatory) located high up on the Palisades overlooking the Hudson River.

Heezen had been a student at Iowa University when Ewing had given a lecture there that inspired Bruce to speak with him afterward. Ewing was so impressed with him, that he invited Bruce to come to Columbia and work with him at Lamont. When Heezen arrived, he was immediately put in charge of an expedition to obtain core samples from the North Atlantic Ocean floor (some of which I may have used later to establish climate variations during the Ice Age). During the following years, Bruce made many trips across all the seas and oceans, and brought back myriad cores and rock samples for Lamont scientists to analyze.

Bruce was a talented scientist and a fast learner who was a master mechanic able to fix any equipment or machinery. His curiosity about the unknown made him always keep the ship's depth-finder on while at sea. He saw that the ocean floor was not all flat and sediment-covered as had been surmised earlier, but that while flat layered sediments were common on the 2-3 miles deep abyss areas that covered more than 40 percent of the world ocean floors, there also were huge mountain ranges, deep trenches, long rift valleys, tall volcanoes, and other seafloor features that proved a bonanza for scientists to analyze. He also saw that a huge submarine canyon (larger than the Grand Canyon) existed on the continental slope south of the Hudson River's mouth - stretching hundreds of miles down from the edge of the continental shelf to the roughly 3-miles deep abyss seafloor.

In wondering what could have created such a spectacular feature, Heezen recalled reading about a curious seafloor event that had taken place in 1929. After a nearby earthquake had occurred, a dozen thick trans-Atlantic cables that connected phone lines from North America to Europe, snapped in sequence from the first one high up on the continental slope, to the lowest one which broke last. The precise times of each break was known because phone calls between Europe and America were extremely expensive then, and operators kept careful track of the time used. The location of each break was also known because the broken ends of each cable were retrieved to be reconnected on surface ships before each cable was dropped back to the bottom to resume functioning.

Knowing the time and location of each break enabled scientists to determine that they had taken place in a submarine canyon and were caused by something moving down the canyon at 60 miles per hour. The only thing that could have broken the thick strong cables, Heezen reasoned, was something like an underwater avalanche that could not be detected in the surface water thousands of feet above. Tests with equipment suspended near the canyon bottom resulted in discovering sporadic, dense, fast-moving, hitherto-unknown turbidity currents that occurred when storms roughed up coastal waters that picked up boulders, pebbles, and smaller particles and carried them across the shelf to the slope where the now-dense bottom currents would accelerate down the steeper incline and form occasional turbidity currents that had eroded the deep submarine canyons and also left tell-tale sediments along the canyon bottom.

When it was Bruce's turn to describe his research project at a weekly geology seminar in which all professors and graduate students had to participate, he was challenged by one of the long-established geology professors who thought submarine canyons were eroded by rivers that had been much longer during the Ice Age when presently submerged coastal land had been exposed by lower sea levels. He said "Come on Bruce, we're aware of your strange theories about turbidity currents leaving glacial sediments in the Hudson Submarine Canyon. But we all know that icebergs breaking off from the glaciers and floating south before melting, dropped their sediments into the canyon." Bruce's reply was classic, "Yes, that's possible, Sir, but you have to admit that it was awfully clever of those icebergs not to melt until they were all lined up directly over the canyon!"