History of Bathymetry: Early Methods

With Google Maps readily available at our fingertips, it’s pretty safe to say that the world has been mapped out. Has it though? Our oceans make up 71 percent of the Earth, but their depths are not accurately mapped out entirely. This series will explain the techniques used in the past and present to record this information, and new methods we hope to put into practice in the future.

Bathymetry is the study of the depths of water in oceans, lakes, and seas from the surface to the bottom. The depths of the ocean vary greatly, so seafarers and scientists have had to rely on methods to calculate this information.

Bathymetry has been around longer than you might think. The first technique of bathymetry started in ancient times and was used up until the 1870s. This method was to lower a weighted, heavy rope into the water from the side of a ship. The depth of the sea was determined by measuring the length of rope needed to reach the sea floor. This rudimentary method was useful in knowing how deep the water was at one specific point so that the ships wouldn’t run aground on an unsuspecting sandbar. There were many downsides to this method because it didn’t take into account currents in the water that could drag the rope or the movement of the ship. Even in the best conditions, the rope could only determine the depth of one specific point on the sea floor.Measuringoceandepthswithrope

The 19th century was when people started investigating and recording the depths of the ocean for scientific discovery and commercial interests. In 1840, British scientist,  Sir James Clark Ross, used the method of lowering a weighted hemp rope and created the first bathymetric map of the Gulf of Mexico. While not very accurate, this map showed features of the Gulf of Mexico that were unknown prior to this time.

In the 1870s, Sir William Thomson attempted to counter the problems posed with the heavy rope method by inventing the Kelvin Sounding Machine. The Kelvin Sounding Machine was much more sophisticated and used piano wire weighted with a lead sinker, instead of rope and could quickly be dropped to the bottom of the ocean floor, saving a lot of time and effort. As long as a determination of the ship’s forward motion was made, this movement would not skew the results as they did before. One of the downsides to this machine was that it still only measured one singular point in the ocean floor, which was still not an accurate representation of the varying depths of the seabed.

These early methods helped grow the study of bathymetry and inspired future scientists to improve the methods. Check out my blog next month as we explore how technological advances changed bathymetry during the 20th century.

The NOAA Looks Back at Failed Whaling Expedition

The whaling industry, once booming, was already declining when a whaling expedition in 1871 became a disaster. This expedition consisted of 40 ships, sailing near Wrainwright, Alaska. The crew of 32 of the ships were forced to evacuate and abandon them in the ice, creating a disastrous loss to the whaling industry. For years following, expeditions were sent to this area to try and recover remains from the lost ships and to learn from what was found. In 2005, archaeological researchers were sent by the National Geographic Society, The National Science Foundation, and the Barrow Arctic Science Consortium on a similar mission to find and study the failed expedition. The National Oceanic and Atmospheric Administration later documented the results of their findings.

The archaeologists were tasked with this four year project not only to benefit future offshore surveys but also to discover exactly what happened during the failed expedition. In order to do this, they had to adjust their understanding of the shoreline near which remains of the vessels were found, as it would have been different at the time of the 1871 expedition. They also had to estimate where ship remains may have traveled over the course of over 100 years. The researchers built on the findings of past archaeologists who had explored the sights to develop conclusions about both of these factors.

The researchers were tasked with uncovering remains that spanned almost 100 miles by searching both the land and the water. They used technology such as remote sensors and techniques such as scuba diving with underwater metal detectors to explore the area under the water. Their exploration above the water consisted of searching for signs of wreckage and miscellaneous artifacts from the 1871 ships. They also were able to study the shoreline from above by flying over the land.

As time passed, the archaeological researchers were able to learn more about the erratic behavior of this Alaskan water and adjusted their methods accordingly. They located which area of water was most likely to hold wreckage based on the water’s behavior and changed the technology they were using to get a clearer view of the underwater space. Unfortunately, they were faced with uncooperative conditions. For example, erosion in the wreckage area is high, and the ice building and moving over the years most likely entrapped remnants of the 1871 fleet ships.

No matter how much specific areas in the large wreck site were singled out, no one piece of wreckage could be matched to a specific ship. This is not only because many of the remains were lost, but also due to the fact that all of the whaling ships were highly similar. Furthermore, many artifacts washed ashore from the wreckage could not be claimed by the researchers because nearby Inupiat villages used pieces of the ships for construction or in personal collections. Thankfully, the villagers took the researchers to the sites and allowed them to inspect the artifacts.

Study of the 1871 whaling ‘disaster’ is important in both archaeological and ocean exploration contexts. The wreckage holds a lot of insight into the past, and it also holds knowledge about the dangers of that specific portion of waters near Wrainwright, Alaska. Although whaling is now generally frowned upon, this information is key in further water travel and ocean exploration in that area.