1. Bathymetry of the Sea Floor
“Mapping the Ocean Floor
How and Why”

2. Terminology abyssal plain isolume (lines of equal light)
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)
Terminology

4. 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

5. 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

6. Application Alert Chesapeake Bay
“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”.

7. Technologies have evolved to more accurately survey the ocean floor

8. 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).

12. George’s Bank Bathymetric Chart

13. Lake Michigan Bathymetric Map showing contour intervals

15. By Nancy J. Hornewer and Marilyn E. Flynn
2008
USGS Project at Upper Lake Mary, Arizona