Concept

Bathymetric chart

Résumé
A bathymetric chart is a type of isarithmic map that depicts the submerged topography and physiographic features of ocean and sea bottoms. Their primary purpose is to provide detailed depth contours of ocean topography as well as provide the size, shape and distribution of underwater features. Topographic maps display elevation above ground and are complementary to bathymetric charts. Charts use a series of lines and points at equal intervals to showcase depth or elevation. A closed shape with increasingly smaller shapes inside of it can indicate an ocean trench or a seamount, or underwater mountain, depending on whether the depths increase or decrease going inward. Bathymetric surveys and charts are associated with the science of oceanography, particularly marine geology, and underwater engineering or other specialized purposes. Bathymetric data used to produce charts can also be converted to which are vertical sections through a feature. Bathymetry#History Ancient Egypt The use of bathymetry and the development of bathymetric charts dates back around the 19th century BC to ancient Egypt. Depictions on tomb walls such as the bas-relief carvings of Deir al-Bahri commissioned by Queen Hatshepsut in the 16th century BC show ancient mariners using long slender poles as sounding poles to determine the depth of the Nile River and into the Nile River Delta. Ancient Greece The first written account and mapped records of sounding did not occur until 1000 years after the Egyptians had begun sounding and mapping the Nile. The Greek historian Herodotus writes of a sounding in 66 feet of water of the mouth of the Nile in the river delta. He writes of yellow mud being brought up similar to the same that was deposited with the yearly floods. These accounts show a heightened awareness of regional depths and seafloor characteristics among ancient mariners and demonstrate that discoveries in bathymetry and the use of bathymetric charts had progressed significantly. The New Testament recounts soundings being taken with the shipwreck of Paul on the island of Malta in the Book of Acts.
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