21. In October 1948, Hydrographic Survey Group 1 arrived to help map the Persian Gulf's waters. 22. The United States Coast Guard also conducts hydrographic survey operations, particularly in the polar regions. 23. From 1904 it was based in Buenos Aires, mostly in support and hydrographic survey duties. 24. Isopach maps are utilized in hydrographic survey , stratigraphy, sedimentology, structural geology, petroleum geology and volcanology. 25. The rock was charted by a Royal Navy Hydrographic Survey Unit from HMS Protector, 1966-67. 26. It was charted by the Hydrographic Survey Unit from RRS " John Biscoe " in 1966. 27. She undertook hydrographic surveys around New Guinea with Captain Moresby and made a number of discoveries. 28. She commenced service on the Australia Station in 1880 as a survey vessel for hydrographic surveys . 29. This section specializes in reconnaissance and hydrographic survey . 30. The islands were more accurately charted by the British Royal Navy Hydrographic Survey Unit in 1963.
