Tectonic Unit: OSD
         Name: Descon
 
  Description: basaltic to andesitic pillow lava, pillow breccia,
               tuff breccia; subordinate rhyolite, pyroclastic
               breccia, tuff and domes; argillite, mudstone,
               siltstone, greywacke, minor limestone; mainly
               marine
 
    Formation: Insular Belt
                  Craig Subterrane of Alexander Terrane
                       S    Heceta
                       OS   Descon and similar rocks in Annette subterrane
 
    Age Range: Ordovician - Silurian
  Maximum Age: 510.0 Ma
  Minimum Age: 408.5 Ma