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information on our web sites. However, some USGS data and information accessed through
these pages may, of necessity, be preliminary in nature and presented prior to final
review and approval by the Director of the USGS. These data and information are
provided with the understanding that they are not guaranteed to be correct or complete.
Users are cautioned to consider carefully the provisional nature of these data and
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Conclusions drawn from, or actions undertaken on the basis of, such data and information
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content of most USGS web pages is in the public domain, not all the information
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You are welcome to make a link to any of the Web pages USGS has published on the
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The USGS identifier is trademarked and must be used in accordance with the rules
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Use of the Trademarked USGS Identifier by Outside Organizations.
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Credit: U. S. Geological Survey
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