<?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:contributor>K.A. Foland</dc:contributor>
  <dc:contributor>John F. Sutter</dc:contributor>
  <dc:contributor>Roger W. Sanders</dc:contributor>
  <dc:contributor>O. Mario Silva</dc:contributor>
  <dc:creator>Tod F. Stuessy</dc:creator>
  <dc:date>1984</dc:date>
  <dc:description>&lt;p&gt;Potassium-argon dating of five basalts from the three main islands of the Juan Fern&amp;aacute;ndez (or Robinson Crusoe) Islands of Chile in the southeastern Pacific gives ages of 1.01 &amp;plusmn; 0.12 and 2.44 &amp;plusmn; 0.14 million years for Masafuera, 3.79 &amp;plusmn; 0.20 and 4.23 &amp;plusmn; 0.16 for Masatierra, and 5.8 &amp;plusmn; 2.1 for Santa Clara. These ages are much younger than that of the underlying oceanic plate and are consistent with the origin of the island-seamount chain from a mantle hot spot beneath the eastward moving Nazca plate. The young age for the archipelago suggests that speciation within endemic genera has occurred within the past 4 to 5 million years. Endemic genera of apparently more ancient origins, such as&lt;span&gt;&amp;nbsp;Lactoris&amp;nbsp;&lt;/span&gt;and&lt;span&gt;&amp;nbsp;Thyrsopteris,&amp;nbsp;&lt;/span&gt;have apparently dispersed to the islands and survive refugially.&lt;/p&gt;</dc:description>
  <dc:format>application/pdf</dc:format>
  <dc:identifier>10.1126/science.225.4657.49</dc:identifier>
  <dc:language>en</dc:language>
  <dc:publisher>AAS</dc:publisher>
  <dc:title>Botanical and geological significance of potassium-argon dates from the Juan Fernández Islands</dc:title>
  <dc:type>article</dc:type>
</oai_dc:dc>