Coastal & Marine Geology InfoBank

Home FACS Activities Atlas Geology School Related Sites More

USGS CMG InfoBank: Life on Land

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: 10:50 - 12:11 (01:21)
Source: Annenberg/CPB Resources - Earth Revealed - 11. Evolution Through Time
Keywords: "Dee Trent", life, atmosphere, oxygen, photosynthesis, stromatolite, algae, ozone, "carbon dioxide", "solar radiation", Precambrian, Paleozoic, limestone, ocean, horse, camel, humans, sycamore, "carbon cycle"

Our transcription: The first appearance of life out of the seas was possible in large part because the planet's atmosphere had become oxygen rich due to photosynthesis of stromatolitic algae.
As oxygen built up, an ozone layer formed high in the atmosphere shielding the Earth's surface from deadly solar radiation.
Although this process was actually well underway in the Precambrian, it was not until the mid Paleozoic that life was sufficiently developed to take advantage of the dry land habitats the ozone layer protected.
At the same time oxygen increased in the atmosphere, another atmospheric gas, carbon dioxide, decreased because carbon dioxide had become an important building block of life.
And a lot of the carbon dioxide is trapped in organisms in seawater and actually eventually becomes limes oozes on the sea floor, which may eventually become limestones.
Organisms are very much a part of the control of our environment.
The plants take in the carbon dioxide and give off oxygen.
The plants, the limestones, the ocean, the atmosphere, human beings, horses and camels, the sycamore tree outside are all interrelated in a big cycle called the "carbon cycle."

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 04:26:19 PDT 2013  (chd)