Bathymetry of the Sea Floor
“Mapping the Ocean Floor
How and Why”
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abyssal plain
isolume (lines of equal light)
Terminology
bathymetry (bathymetric)
isometric (lines of equal measure)
continental shelf
isotherm (lines of equal temperature)
continental slope
mid-ocean ridge
contour lines (lines of equal height)
profile
guyot
seamount
isobar (lines of equal pressure)
topographic map
isobath (lines of equal depth)
trench
isohaline (lines of equal salinity)
Topography in the Oceans?
“Topography can be used to identify and
characterize deep water features of the
seafloor to reveal upwelling-producing
canyons, ridges, and escarpments. Digital
data can be correlated with sea surface
temperature and chlorophyll, and
distribution of marine birds, mammals, and
fishes/invertebrates.” – NOAA Bathymetry
California
Purposes for Bathymetry
• Determine the bottom depth and contour
these depths for bottom analysis
• Determine topographic features by looking
from the top down and bottom
geomorphology
• Detail physical factors including water
current, sediment transport, slope and
areas for layering, etc…
• Use values for comparisons of changing
bottom features and movement of
sediments
“The deepest parts of the Chesapeake Bay and its estuaries may represent a
natural barrier to cross-channel sediment transport. This map was developed as
a starting point to assist in modeling sediment transport in the Bay”.
Technologies have evolved to more accurately
survey the ocean floor
http://www.earthguide.ucsd.edu/earthguide/diagrams/
sonar/sonar.html
Using echo sounding to determine depth
Measuring water depth: Echosounding
Test your knowledge
If a sound pulse takes 2 seconds to travel to the seafloor and return to the ship, what
is the depth to the seafloor? (Use 1500 m/sec as the speed of sound).
George’s Bank Bathymetric Chart
Lake Michigan Bathymetric
Map showing contour
intervals
By Nancy J.
Hornewer and
Marilyn E. Flynn
2008
USGS Project at
Upper Lake Mary,
Arizona