CONTACT:       Patricia Viets            FOR IMMEDIATE RELEASE
               NOAA/NESDIS PA            10/22/96
               Peter Sloss
               NOAA/NGDC

NEW NOAA POSTER DEPICTS AGES OF THE OCEAN FLOOR

A new color poster that depicts the ages of the ocean floor has been published by NOAA's National Geophysical Data Center in Boulder, Colo., the National Oceanic and Atmospheric Administration announced today. The poster is the first showing clearly the relation between crustal age of the ocean basin floors and ocean floor relief. A color image showing crustal ages as colored bands is painted over shaded relief maps and globes.

"The poster highlights one of the most amazing discoveries made by geologists in the late 20th century, namely, that the age of the crust beneath the ocean floor is quite young, geologically speaking, being everywhere less than about 180 million years old," said Peter W. Sloss, of the data center's Marine Geology and Geophysics Division.

Oceanic crust is slowly "recycled," being formed at the mid-ocean ridges, transported in conveyor-belt fashion across the ocean floor, and finally destroyed along "subduction zones," where slabs of oceanic crust re-enter the earth's mantle and are consumed, Sloss said. Beneath the continents, on the other hand, the earth's crust is typically billions of years old. Continental crust tends to be preserved at the earth's surface because, being less dense than oceanic crust, it resists subduction, Sloss explained..

New crust is being formed continuously at the axes of the mid-ocean ridges, along which the youngest crustal ages occur. A look at the poster reveals that crustal ages increase with increasing distance from the mid-oceanic ridges, as shown by the progression of the color bands. Widths of the color bands are proportional to the rate at which new crust is being formed, transported, and consumed. High rates occur beneath the east Pacific Ocean, whereas much lower rates occur beneath the north Atlantic and western Indian Oceans. The oldest oceanic crust occurs beneath the north Atlantic and western Indian Oceans nearest the continents, and beneath the western Pacific Ocean adjacent to the oceanic trenches in mid-latitudes..

The color ages overlay image was created by R. Dietmar M�ller of the Scripps Institution of Oceanography from crustal age and other data contributed by institutions in Australia, Canada, France, and the United States. The image was created from a digital age grid of the ocean floor. The age at each grid node was determined mathematically using available data. Ages for the ocean floor between the oldest identified magnetic anomalies and continental crust were interpolated by estimating the ages of passive continental margin segments from geological data and published plate models. The crustal age coloration was then applied to computer-rendered relief images derived from topographic data, Sloss said..

The poster can be previewed on the World Wide Web at: http://www.ngdc.noaa.gov/mgg/announcements/announce_crustage.html.

NGDC is one of three major data and information centers of NOAA's National Environmental Satellite, Data, and Information Service. NGDC houses data in the fields of solid earth geophysics, marine geology and geophysics, solar-terrestrial physics, and paleoclimatology. NGDC fills tens of thousands of requests each month for data services and publications..

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