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Posted by on Mar 31, 2020 in TellMeWhy |

When Was the Ocean Floor First Mapped Accurately?

When Was the Ocean Floor First Mapped Accurately?

The earliest methods of depth measurement on record are the use of sounding poles and weighted lines, recorded from Egypt more than 3000 years ago, and in use without significant improvement until the voyage of HMS Challenger in the 1870s, when similar systems using wires and a winch were used for measuring much greater depths than previously possible, but this remained a one depth at a time procedure which required very low speed for accuracy.

The shape of the ocean floor was not accurately determined until the 1920s. Until the end of the last century mapping had depended on the accounts by sailors of rock formations and deep troughs in the ocean bed. Recent scientific developments, and new instruments and techniques have enabled maps to be drawn with greater accuracy and detail. By transmitting sound waves from ships to the sea bed, and back, it is possible to make a record of the changes in depth.

Mechanical, acoustical and electronic instruments have pictured the ocean floor not as a vast plain but as a series of mountain ranges, valleys, peaks and canyons. Some of the mountains are far higher than most of those on land and the deepest part of the ocean is much farther below sea level than the highest land mountain is above it.

At the beginning of the twentieth century mapping the seafloor was a very difficult task. The mapping of the seafloor started by using sound waves, contoured into isobaths and early bathymetric charts of shelf topography. These provided the first insight into seafloor morphology, though mistakes were made due to horizontal positional accuracy and imprecise depths. In 1957, Marie Tharp, working alongside with Bruce Charles Heezen created the first three-dimensional physiographic map of the world’s ocean basins.

Tharp’s discovery was made at the perfect time. It was one of many discoveries that took place near the same time as the invention of the computer. Computers, with their ability to compute large quantities of data, have made research much easier, include the research of the world’s oceans.

There has been a boom in the underwater environmental exploration; rather than simply creating a map, scientists are attempting to visualize the entire seafloor with maximum possible detail. Computers are put to good use here with their help, researchers have managed to store and analyze large quantities of data. This led to the creation of the first digital map of the world ocean bed in 1970. Constantly developing technology allows computing to take place in the special equipment required for “high-resolution orthoimagery”. This means researchers may no longer need to use sound frequencies to conduct marine exploration.

This method was later upgraded to Airborne Laser Bathymetry (ALB). ALB provides images that are both higher quality and in color. The improvements to these research methods and the large amount of data received, stored and computed all led to the creation of one of the first color images of the underwater environment created on a computer.

Content for this question contributed by John Merion, resident of Milliken, Weld County, Colorado, USA