Mapping the Ocean Floor
"Contours, 0504N" for Atlantic Ocean
Colored pencil on mylar and
graphite on paper, July 1973
Geography & Map Division
Gift of Marie Tharp, 1995-96 (118.1)
For 30 years, oceanographic cartographer Marie Tharp and marine
geologist Bruce Heezen compiled the first comprehensive physiographic
diagram of the ocean floor. Using such data as continuous echograms
and closely spaced depth soundings, they constructed preliminary
contour diagrams, such as the one for this area in the North Atlantic.
These diagrams demonstrated that the sea floor was not a monotonous
"abyssal plain," as many had previously thought, and that mid-ocean
ridges paralleled the shapes of the continents, thus setting the
stage for the acceptance of the theory of plate tectonics.