Coastal & Marine Geology InfoBank

Home FACS Activities Atlas Geology School Related Sites More

USGS CMG InfoBank: Unconformities

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: 16:25 - 17:32 (01:07)
Source: Annenberg/CPB Resources - Earth Revealed - 8. Earth's Structures
Keywords: "James Sadd", "James Hutton", "geologic structure", unconformity, erosion, "sedimentary rock", contact

Our transcription: Unconformities, the third great class of geologic structure are not as useful as folds and faults in analyzing past crustal stress.
Nonetheless, they too have proven to be an important key to the past.
Just as astronomers are preoccupied with the immensity of space, geologists are uniquely fascinated with time and Earth history.
The first geologist to actually recognize the scale of geologic time was a Scotish intellectual named James Hutton.
Over a century ago, Hutton recognized that a sequence of layered rocks is a physical record of some portion of Earth history.
He also predicted that in places where mountain building has occurred some part of that record would be destroyed by erosion.
Armed with this hypothesis, Hutton found places where old rocks had been covered by much younger sedimentary rocks.
A contact between these two rock formations marked a period of Earth history with no rock record.
This geologic structure is called an unconformity.

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 04:28:23 PDT 2013  (chd)