Maryland Department of Natural Resources

Chesapeake Bay Sediment Distribution - Raster Image

contact: Bob Conkwright (bob.conkwright@maryland.gov)

     You can save this image to your computer and print it. Place you mouse over the image and RIGHT-CLICK you mouse button. A small menu will pop up by you mouse. Select "Save image as.." (Netscape) or "Save picture as" (IE) and save the image to a file on your computer. You can then open the image in a graphics program such as Paint Shop Pro, Photo Shop, Paint, etc., and print the image.

     We also have this map in an interactive format and in Adobe Acrobat PDF format. You need the Autodesk Whip! plugin for Netscape or Internet Explorer (Windows 95, 98 and NT only). For more information, see the Interactive Map pages.

Click an icon to obtain this map in other formats:
Chesapeak Bay Sediment Distribution Map


 

Adobe Acrobat PDF Document
Adobe PDF
Interactive Map, requires a plugin
Interactive Data
Download ASCII Data
ASCII Data
Download ASCII Data
ESRI Shape file
Explanation of Sediment Distribution Map

    Based on the proportions of sand-, silt- and clay-sized particles, bottom sediments were classified according to Shepard's diagram (see map legend below). Shepard's diagram is an example of a ternary diagram - a device for graphing a three-component system summing to 100%. In this case, the components are the percentages of sand, silt, and clay comprising a sediment sample. Each sediment sample plots as a point within or along the sides of the diagram, depending on its specific grain size composition. A sample consisting entirely of one of the components, 100% sand, for example, falls at the same-named apex. A sediment entirely lacking in one of the components falls along the side of the triangle opposite that apex. The rest fall somewhere in between.

      To classify sediment samples, Shepard (1954) divided a ternary diagram into ten classes. Shepard's diagram follows the conventions of all ternary diagrams. For example, Shepard's "Clays" contain at least 75% clay-sized particles. "Silty Sands" and "Sandy Silts" contain no more than 20% clay-sized particles, and "Sand-Silt-Clays" contain at least 20% of each of the three components. The exact boundaries of each of the ten classes are described in the metadata for the data set used to compile the sediment distribution map.

Map Legend
(Shepard Diagram)

Reference
     Shepard, F.P., 1954, Nomenclature based on sand-silt-clay ratios: Journal of Sedimentary Petrology, v. 24, p. 151-158

Examples of how to interpret the Shepard diagram


Return to previous page | Go to the CG Home Page
Next Page Jump to C&EG Home Page Return