<?xml version='1.0' encoding='utf-8'?>
<oai_dc:dc xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/oai_dc/ http://www.openarchives.org/OAI/2.0/oai_dc.xsd">
  <dc:creator>H. J. Moore</dc:creator>
  <dc:date>1980</dc:date>
  <dc:description>&lt;p&gt;&lt;span class="TextRun SCXW37812607 BCX8" lang="EN-US" xml:lang="EN-US" data-contrast="auto"&gt;&lt;span class="NormalTextRun SCXW37812607 BCX8"&gt;The area included in the Sinus &lt;/span&gt;&lt;span class="SpellingError SCXW37812607 BCX8"&gt;Sabaeus&lt;/span&gt;&lt;span class="NormalTextRun SCXW37812607 BCX8"&gt; quadrangle represents an &lt;/span&gt;&lt;span class="ContextualSpellingAndGrammarError SCXW37812607 BCX8"&gt;ancient cratered&lt;/span&gt;&lt;span class="NormalTextRun SCXW37812607 BCX8"&gt; surface that has been &lt;/span&gt;&lt;span class="NormalTextRun SCXW37812607 BCX8"&gt;modified by a combination of impact cratering, fluvial, eolian, and, probably, volcanic processes. Impact cratering has been the dominant process. Cumulative frequencies of craters larger than 20 km for the entire quadrangle (fig. 4) are only about a factor of two below the &lt;/span&gt;&lt;span class="NormalTextRun SCXW37812607 BCX8"&gt;idealized lunar steady-s&lt;/span&gt;&lt;span class="NormalTextRun SCXW37812607 BCX8"&gt;ta&lt;/span&gt;&lt;span class="NormalTextRun SCXW37812607 BCX8"&gt;te curve (Moor&lt;/span&gt;&lt;span class="NormalTextRun SCXW37812607 BCX8"&gt;e&lt;/span&gt;&lt;span class="NormalTextRun SCXW37812607 BCX8"&gt;, 1964; Trask, 1966). Two of the units mapped (hilly, &lt;/span&gt;&lt;span class="NormalTextRun SCXW37812607 BCX8"&gt;channeled&lt;/span&gt;&lt;span class="NormalTextRun SCXW37812607 BCX8"&gt;, and cratered material a&lt;/span&gt;&lt;span class="NormalTextRun SCXW37812607 BCX8"&gt;n&lt;/span&gt;&lt;span class="NormalTextRun SCXW37812607 BCX8"&gt;d hilly and cratered&lt;/span&gt;&lt;span class="NormalTextRun SCXW37812607 BCX8"&gt; material) have cumulative &lt;/span&gt;&lt;span class="NormalTextRun SCXW37812607 BCX8"&gt;frequencies of craters larger than 40 km that are near the same as the idealized steady-state curve. The young map units (smooth plains &lt;/span&gt;&lt;span class="NormalTextRun SCXW37812607 BCX8"&gt;material and units of the crater &lt;/span&gt;&lt;span class="SpellingError SCXW37812607 BCX8"&gt;Bakhuysen&lt;/span&gt;&lt;span class="NormalTextRun SCXW37812607 BCX8"&gt;) have cumul&lt;/span&gt;&lt;span class="NormalTextRun SCXW37812607 BCX8"&gt;ative frequencies of craters a &lt;/span&gt;&lt;span class="ContextualSpellingAndGrammarError SCXW37812607 BCX8"&gt;distributions&lt;/span&gt;&lt;span class="NormalTextRun SCXW37812607 BCX8"&gt; that are similar in form and magnitude &lt;/span&gt;&lt;span class="NormalTextRun SCXW37812607 BCX8"&gt;to the average frequency distributions of lunar maria. Ages of surfaces recorded by craters larger than 5 km (fig. 4) are probably measured in several billions of years. Direct comparison with lunar cra&lt;/span&gt;&lt;span class="NormalTextRun SCXW37812607 BCX8"&gt;t&lt;/span&gt;&lt;span class="NormalTextRun SCXW37812607 BCX8"&gt;ers would place the age of the young units (smooth plains&lt;/span&gt;&lt;span class="NormalTextRun SCXW37812607 BCX8"&gt; material and units of &lt;/span&gt;&lt;span class="SpellingError SCXW37812607 BCX8"&gt;Bakhuysen&lt;/span&gt;&lt;span class="NormalTextRun SCXW37812607 BCX8"&gt;) &lt;/span&gt;&lt;span class="NormalTextRun SCXW37812607 BCX8"&gt;i&lt;/span&gt;&lt;span class="NormalTextRun SCXW37812607 BCX8"&gt;n the range 3.2 to 3.5 billion years, but procedures &lt;/span&gt;&lt;span class="NormalTextRun SCXW37812607 BCX8"&gt;for making such a comparison are controversial. (See, for example, Soderblom and others, 1974&lt;/span&gt;&lt;span class="NormalTextRun SCXW37812607 BCX8"&gt;; &lt;/span&gt;&lt;span class="SpellingError SCXW37812607 BCX8"&gt;Neukum&lt;/span&gt;&lt;span class="NormalTextRun SCXW37812607 BCX8"&gt; and Wise, 1976). These units may be either a few tenths of a billion years older or about a billion &lt;/span&gt;&lt;span class="NormalTextRun SCXW37812607 BCX8"&gt;years younger than the average lunar maria. The more cratered units (hilly, channel&lt;/span&gt;&lt;span class="NormalTextRun SCXW37812607 BCX8"&gt;e&lt;/span&gt;&lt;span class="NormalTextRun SCXW37812607 BCX8"&gt;d, and cratered material and hill&lt;/span&gt;&lt;span class="NormalTextRun SCXW37812607 BCX8"&gt;y and cratered material) may represent the cumulative result of about 4 billion years of cratering (Soderblom and others, 1974&lt;/span&gt;&lt;span class="NormalTextRun SCXW37812607 BCX8"&gt;; &lt;/span&gt;&lt;span class="SpellingError SCXW37812607 BCX8"&gt;Neukem&lt;/span&gt;&lt;span class="NormalTextRun SCXW37812607 BCX8"&gt; and Wise, 1976).&lt;/span&gt;&lt;/span&gt;&lt;/p&gt;</dc:description>
  <dc:format>application/pdf</dc:format>
  <dc:identifier>10.3133/i1196</dc:identifier>
  <dc:language>en</dc:language>
  <dc:publisher>U.S. Geological Survey</dc:publisher>
  <dc:title>Geologic map of the Sinus Sabaeus quadrangle of the Mars</dc:title>
  <dc:type>reports</dc:type>
</oai_dc:dc>