The Glomar Challenger was a research vessel from the National Science Foundation that laid the groundwork for accurate maps of the age of the ocean floor.
Although the oceanic crust was generally known to be much younger than continental crust, it was not until extensive ocean drilling started in the late 1960s that clear maps of the age of the seafloor emerged. Underwater drilling technology developed as commercial oil companies began investigating offshore sources of oil. This drilling technology was then adapted by scientific research vessels such as the Glomar Challenger. Oceanic drilling by the Glomar Challenger between 1968 and 1983 resulted in our first accurate knowledge about the age of the seafloor.
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Glomar Challenger Trivia
During its 15 year history, the Glomar Challenger traveled an astonishing 375,632 nautical miles (695,670 km) and investigated a total of 624 sites. Drilling at these sites resulted in 19,119 drill cores being recovered. The total length of these recovered and stored drill cores was 97,056 meters (318,425 feet). The name Glomar, incidentally, is a contraction of Global Marine.Data from the Glomar Challenger clearly showed a progression in age of oceanic sediment the farther away one got from the mid-oceanic ridges. Sediment next to a mid-oceanic ridge was youngest, while the oldest sediment was close to continental shelves, the greatest distance away from the mid-oceanic ridges. This progression in the age of seafloor sediment served to further corroborate the theory of seafloor spreading.
Try This
The Rate of Seafloor Spreading in the North Atlantic
- Click here to see a map of the age of the seafloor in the North Atlantic.
- Use the measuring tool to measure the distance (in km) along the 40° line of latitude from the Mid-Atlantic Ridge to the edge of the continental shelf off Europe. The distance is approximately 1,450 km. (Note: Answers may vary slightly because of accuracy.)
- Use the age scale to determine the maximum age of the seafloor off the European continental shelf. The age is approximately 120 million years. (Note: Answers may again vary slightly depending on the exact color match using the age scale.)
- Calculate the average rate of seafloor spreading (in cm/year) from the Mid-Atlantic Ridge that must have occurred in order to account for this seafloor age off the European continental shelf. Using the measured values in questions 1 and 2, the average rate of seafloor spreading is approximately 1.21 cm/year.
- Repeat this process to calculate the average rate of seafloor spreading from the Mid-Atlantic Ridge to the North American continental shelf, again along the 40° line of latitude. Measurements indicate a total distance of approximately 3,400 km, and a maximum age of 180 million years. (Note: These values may, again, vary slightly because of differences in measurement.) The average rate of seafloor spreading west of the Mid-Atlantic Ridge is approximately 1.89 cm/year.
- Compare your two calculated rates from questions 3 and 4. Which part of the Atlantic was spreading faster at this latitude, and by how much? The Atlantic seafloor east of the Mid-Atlantic Ridge is spreading at an average speed of 1.21 cm/year, while west of the ridge its average speed is 1.89 cm/year. The seafloor west of the Mid-Atlantic Ridge is spreading faster, by 0.68 cm/year.
- Which part of the Atlantic is older at this particular latitude? The eastern part of the Atlantic is older than the western part at this latitude by approximately 60 million years.
- Rotate the globe. Where is the greatest amount of old ocean crust? The greatest amount of old ocean crust is located in the western part of the Pacific Ocean.