Coastal & Marine Geology InfoBank

Home FACS Activities Atlas Geology School Related Sites More

USGS CMG InfoBank: Deltas

Skip navigational links
Dictionaries: Our Mapping Systems   The USGS and Science Education   USGS Fact Sheets   Topics   Keywords   Data Dictionary   Metadata Dictionary   Computer Terminology   Digital Formats  
InfoBank Terms: Activity ID   activity overview   crew   digital data   formal metadata   lines   metadata   NGDC   port stops   project/theme   region   ship   stations   time   virtual globe   year  
Data Types: bathymetry   biological   geochemical   gravity   ground penetrating radar   imaging   LIDAR   logs   magnetics   metering equipment   navigation   samples   seismic   total station   definitions disclaimer  
Data Formats: ARC coverage   E00   FGDC metadata   gridded/image   imaging   material   scattered/swath   Shapefile   vector/polygon  
Comment: 10:05 - 11:08 (01:03)
Source: Annenberg/CPB Resources - Earth Revealed - 20. Running Water II: Landscape Evolution
Keywords: "Dee Trent", valley, river, landscape, landform, stream, ocean, lake, "flow velocity", deposition, delta, slope, gradient, sediment, deposition, distributary, "river channel"

Our transcription: River valleys form a significant part of Earth's landscape, but they are not the only landform created by running water.
All streams and rivers come to an end.
Most ultimately flow into the ocean or another large body of water such as a lake.
Due to the sudden loss in velocity at the mouth of a river, most of its sediment is deposited forming a "delta."
Deltas, of course, form at the mouth of the river where they enter a large lake or the ocean.
The gradient or the slope of the river is very gentle.
When it hits the water there is no gradient; consequently, the sediment begins to settle out immediately.
In so doing, it dams its channel, and the river tends to branch into a series of "distributaries."
From time to time the certain branches load up with more sediment than others, so the main flow of the river may shift from one locality to another over a long period of time.

Geology School Keywords
Skip footer navigational links

Coastal and Marine Science Centers:  Pacific   St. Petersburg   Woods Hole  
InfoBank   Coastal and Marine Geology Program   Geologic Information   Ask-A-Geologist   USGS Disclaimer  

Accessibility FOIA Privacy Policies and Notices

Take Pride in America logo logo U.S. Department of the Interior | U.S. Geological Survey
Page Contact Information: InfoBank staff
Page Last Modified: Thu Oct 31 04:28:08 PDT 2013  (chd)