Coastal & Marine Geology InfoBank

Home FACS Activities Atlas Geology School Related Sites More

USGS CMG InfoBank: Mud Cracks

Skip navigational links
Loading
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: 16:36 - 17:49 (01:13)
Source: Annenberg/CPB Resources - Earth Revealed - 17. Sedimentary Rocks: The Key to Past Environments
Keywords: "Walter E. Reed", "sedimentary rock", "clastic sediment", "sedimentary structure", "mud crack", fissure, deposition, "depositional environment", "river bed", "tidal flat", desiccation, preservation, sand, river, "natural levee", floodplain, meander, "braided stream", delta, climate

Our transcription: Sometimes the surface of a fine sedimentary bed is also broken up into a pavement of fossil "mud cracks", either with the fissures still open or with the gaps filled in by later deposits of sediments.
Mud cracks are a very good indicator of environments.
We've all been in river beds or in tidal flats in which we've seen desiccation and formation of mud crack.
These are preserved in the geologic record if sand is washed over that mud crack, it infiltrates down into the crack and preserves the crack.
We can identify them in river deposits.
They show up on natural levees.
They show up on flood plains, and so forth.
They show up in meandering as well as braided streams.
They show up in deltaic deposits where a given delta distributary is stranded or abandoned.
And so they can be very useful to us because they tell us that the situation at the time of sedimentation was such that it became dry.

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 USA.gov logo U.S. Department of the Interior | U.S. Geological Survey
URL: http://walrus.wr.usgs.gov/infobank/programs/html/school/moviepage/16.01.20.html
Page Contact Information: InfoBank staff
Page Last Modified: Thu Oct 31 04:27:09 PDT 2013  (chd)