A 1925 map of the Russian sector of the Arctic Ocean showing discoveries made from 1911 to 1915 by Russian surveyors and explorers. This map was published as "The Russian Hydrographical Expedition to the Arctic" in The Geographical Review, Vol. XV, No. 3, 1925.

Map showing the route and profile of soundings obtained by the USS STEWART in 1922. The STEWART crossed the Atlantic and ran a complete line of acoustic soundings and obtained over 900 measurements of depth from the East Coast of the United States to the Straits of Gibraltar. Although not the first line of acoustic soundings, it ushered in the use of acoustics in ocean exploration.

The Atlantic Ocean in "Geographic das Atlantischen Ozeans", 1925, published by Gerhard Schott on the eve of the famous German METEOR Expedition in 1925. There are few, if any, substantive changes between this map and Schott's 1912 map. Most of the large features of the ocean floor had been discovered by the early 1900's. However, ocean scientists were on the edge of a new era of discovery.

The North Atlantic Ocean and Arctic Ocean in: "Geographic das Atlantischen Ozeans", 1925, published by Gerhard Schott. This was in the second edition of his work on Oceanography and basically showed that little additional knowledge of this area had been obtained since 1912. See image map00062.

This 3-dimensional view of the equatorial Atlantic seafloor was produced following the German METEOR Expedition of 1925-1927. Unfortunately it was destroyed during the Second World War but the image survives. The Mid-Atlantic Ridge snakes down the middle of the Atlantic Ocean between Brazil on the left and Africa on the right.

State of knowledge of the Southern Ocean in 1929 as compiled by the American Geographical Society.

"Echometre" record obtained by the French liner S.S. De Grasse when crossing over the head of a canyon on Georges Bank. Such records reinforced the view that vessels could navigate by using bathymetry. Accordingly, the United States Coast and Geodetic Survey embarked on a project to map the continental slopes and shelves to help guide mariners into United States ports.

This submarine valley was discovered by the U.S. Coast and Geodetic Survey during survey operations using acoustic sounding systems coupled with the newly developed Radio Acoustic Ranging (RAR) navigation system allowing relatively accurate navigation without having to rely on either visual astronomic positioning or visual ties to objects on land.

These canyons were discovered by the United States Coast and Geodetic Survey on the continental slope south of Georges Bank. They were contoured by Francis Shepard, the Father of Submarine Geology, who began his career as a marine geologist working cooperatively with the USC&GS.

Map of the Atlantic Ocean by Theodore Stocks following the completion of the German METEOR Expedition.

"Gravimetrical-Geological Map of the East Indian Archipelago" by Vening Meinesz, et al. In: Gravity Expeditions at Sea 1923-1932. 1935 Vol II. Plate IV. This map is possibly the first to hint at the correlation between gravity and bathymetry as the Java Trench is mirrored by the red and pink negative gravity anomaly south of the island of Java.

Map of the Atlantic Ocean published following the METEOR Expedition by Theodor Stocks and George Wust in: "Die Tiefenverhaltnisse des Offenen Atlantischen Ozeans" 1935.

Title page to "Die Tiefenverhaltnisse des Offenen Atlantischen Ozeans" 1935. By Theodor Stocks and George Wust. This work was an analysis of the bathymetry of the METEOR cruise showing the most detailed morphological information of the seafloor ever attained up to that time. It clearly showed the nature of the Mid- Atlantic Ridge and led eventually to the discovery of the median valley.

The echo-sounding profiles of the South Atlantic Ocean as correlated along longitude 30W. These profiles were generated following the METEOR Expedition by Theodor Stocks and George Wust and published in: "Die Tiefenverhaltnisse des Offenen Atlantischen Ozeans" 1935, Table I.

A series of stacked profiles which possibly were used in the building of the seafloor model shown in image map00077. In: "Die Tiefenverhaltnisse des Offenen Atlantischen Ozeans" 1935, by Theodor Stocks and George Wust.

The center of the Mid-Atlantic Ridge showing where soundings had been made. In: "Die Tiefenverhaltnisse des Offenen Atlantischen Ozeans" 1935, by Theodor Stocks and George Wust.

Some of the large features noted on the Stocks and Wust map in: "Die Tiefenverhaltnisse des Offenen Atlantischen Ozeans" 1935, by Theodor Stocks and George Wust.

An attempt to understand the morphology of the Romanche Deep area, an area known today to be the location of a major fracture zone offsetting the Mid- Atlantic Ridge. In: "Die Tiefenverhaltnisse des Offenen Atlantischen Ozeans", 1935, by Theodor Stocks and George Wust.

A longitudinal diagram of the Mid-Atlantic Ridge showing its high points from 60 N latitude to approximately 60S latitude. In: "Die Tiefenverhaltnisse des Offenen Atlantischen Ozeans", 1935 by Theodor Stocks and George Wust.

Two alternate interpretations of what is now termed the "tectonic fabric" of the seafloor in the vicinity of the Mid-Atlantic Ridge. The lower map is in accordance with modern mapping and interpretation and shows hills and ridges running parallel to the axis of the Mid-Atlantic Ridge. In: Die Tiefenverhaltnis se des Offenen Atlantischen Ozeans", 1935 by Theodor Stocks and George Wust.

A map showing the abyssal hills to the west of the Mid-Atlantic Ridge at 16S. In: "Die Tiefenverhaltnisse des Offenen Atlantischen Ozeans", 1935 by Theodor Stocks and George Wust.

A map of the world ocean between about 50N and 10S in: In: Gravity Expeditions at Sea 1923-1932. 1935. Vol II, Plate I, by Vening Meinesz, et al. Map shows location of gravity profiles in the world ocean up to that time.

1935 map of the Indian and Pacific Oceans by Gerhard Schott. In: :Geographie des Indischen und Stillen Ozeans," 1935. Table IV in back pocket. The East Pacific Rise, South Pacific Swell, Carlsberg Ridge, the Pacific trenches, but still no Ninety East Ridge.

"Distribution of Earthquakes" as mapped by Commander Nicholas Heck of the United States Coast and Geodetic Survey and published in the Transactions of the American Geophysical Union for 1936 (P. 93) clearly showing the seismicity of the Mid-Atlantic Ridge and some other segments of the world rift system.

Distribution of surveyed areas and survey lines in the Indian Ocean.

Distribution of surveyed areas and survey lines in the North Pacific Ocean.

Distribution of surveyed areas and survey lines in the South Atlantic Ocean.

Distribution of surveyed areas and survey lines in the South Pacific Ocean.

Salt domes discovered by Coast and Geodetic Survey, described and interpreted by Francis Shepard. GSA Bulletin; September 1937; v. 48; no. 9; p. 1349-1361

Mississippi Canyon discovered by Coast and Geodetic Survey, described and interpreted by Francis Shepard. GSA Bulletin; September 1937; v. 48; no. 9; p. 1349-1361

1937 tectonic map including offshore bathymetry of Portugal showing numerous offshore canyons. Part of Bruce Heezen collection at NOAA Central Library.

A single salt dome off Southwest Pass of the Mississippi River discovered by the Coast and Geodetic Survey, contoured by Francis Shepard. GSA Bulletin; September 1937; v. 48; no. 9; p. 1349-1361.

1938 3-D model of the North Pacific Ocean based on soundings taken by the USS RAMAPO during numerous crossings of the North Pacific Ocean. This model was produced by the Navy Hydrographic Office.

Francis Shepard's diagram showing worldwide distribution of known submarine canyons. The predominance of known canyons off the United States and the Philippines is the result of work of the United States Coast and Geodetic Survey and its development of the radio-acoustic ranging navigation system prior to WW II. Published in Geographical Review, July, 1938.

Altair Seamount as surveyed by the German Research vessel ALTAIR. This, and Davidson Seamount on the West Coast of the United States, by the Coast and Geodetic Survey were among the first detailed studies of seamounts by acoustic soundings. Contoured by Albert Defant 1939. Published in International Hydrographic Review.

1939 chart of the Caribbean by Navy Hydrographic Office showing state of knowledge of bathymetry of the Caribbean and surrounding seas.

1939 chart of the Caribbean by Navy Hydrographic Office showing state of knowledge of bathymetry of the Caribbean and surrounding seas.

1939 chart of the Caribbean by Navy Hydrographic Office showing state of knowledge of bathymetry of the Caribbean and surrounding seas.

Spectacular cross-section of the Mid-Atlantic Ridge clearly showing median valley obtained as the result of soundings taken on the German research vessel METEOR. This profile and the accompanying paper by Gunter Dietrich clearly establishes Dietrich as the first to recognize the continuity of the median valley of the Mid-Atlantic Ridge. 1938 original publication.

Profiles surmising the continuity of what are now called abyssal hills in the vicinity of the Mid-Atlantic Ridge. Illustration strikingly similar to tracing continuity of magnetic anomaly pattern. Produced by Gunter Dietrich 1938.

Title page of "Some Morphological Results of the Cruise of the "METEOR" January to May 1938" by Gunther Dietrich. Published in International Hydrograph ic Review 1939. This article clearly establishes Gunther Dietrich as the first to note the median valley of the Mid-Atlantic Ridge. Pp. 52-55.

2nd page of "Some Morphological Results of the Cruise of the "METEOR" January to May 1938" by Gunther Dietrich. Published in International Hydrograph ic Review 1939. This article clearly establishes Gunther Dietrich as the first to note the median valley of the Mid-Atlantic Ridge. Pp. 52-55.

3nd page of "Some Morphological Results of the Cruise of the "METEOR" January to May 1938" by Gunther Dietrich. Published in International Hydrograph ic Review 1939. This article clearly establishes Gunther Dietrich as the first to note the median valley of the Mid-Atlantic Ridge. Pp. 52-55. Note the final paragraph of this page.

4th page of "Some Morphological Results of the Cruise of the "METEOR" January to May 1938" by Gunther Dietrich. Published in International Hydrograph ic Review 1939. This article clearly establishes Gunther Dietrich as the first to note the median valley of the Mid-Atlantic Ridge. Pp. 52-55. Dietrich here describes the parallel undulations marching off the crest of the main ridge.

A very small-scale map of the world ocean produced by the International Hydrographic Bureau in 1939. Perhaps because of the patterning, this map has a somewhat odd appearance.

Josephine Bank as contoured by Albert Defant in 1939 from acoustic soundings.

Section of 1939 North Pacific chart 5486 by Navy Hydrographic Office showing hundreds of seamounts, the true configuration of the Aleutian Trench, and some of the southern seamounts of what became known as the Emperor Seamount Chain extending north from the vicinity of Midway Island.

Southeast section of 1939 North Pacific chart 5486 by Navy Hydrographic Office showing use of name Albatross Plateau for East Pacific Rise leading into Gulf of California. It was not until 1960 that H.W. Menard popularized the name East Pacific Rise.

Northeast section of 1939 North Pacific chart 5486 by Navy Hydrographic Office showing few of the seamounts surveyed by the C&GS during the years 1925-1939. See images map00126-map00128.

C&GS Chart 5101A, 1939, a prototype chart incorporating bathymetry acquired with RAR navigation by the C&GS out to oceanic depths. This chart was meant for navigation by following bottom contours. No other chart like this was ever produced as WWII intervened and the use of electronic navigation systems became widespread. The C&GS surveyed the continental margin of the U.S. by 1939.