3.                           W I L L A M E T T E   V A L L E Y                                                                                                                                                                                                                                                                                                                                                            


      Level IV Ecoregion                                   Physiography                                                              Geology                                                                          Soil                                                                        Climate                                            Potential Natural                         Land Use and Land Cover    
                                Area                                                           Elevation /                  Surficial material and bedrock                Order (Great Groups)                             Common Soil Series                Temperature  /     Precipitation     Frost Free      Mean Temperature                       Vegetation                                                       
                               (square                                                        Local Relief                                                                                                                                                  Moisture Regimes    Mean annual       Mean annual      January min/max;
                               miles)                                                             (feet)                                                                                                                                                                          (inches)            (days)      July min/max, ( F)                                                                                      

3a.  Portland/                  574 Undulating terraces and floodplains with low                 0-300         Pleistocene unconsolidated and semi-                 Mollisols (Haplaquolls, Argixer-         Sauvie, Rafton, Hillsboro, Gee, Dollar,            Mesic/             37-50           165-210             34/45;           Prairies (maintained by Native                 Urban/suburban/rural residential/industrial
                                           gradient, meandering streams. Numerous                   /          consolidated, glacial/fluvial deposits in a          olls, Endoaquolls), Inceptisols          Multnomah, Latourell, Quatama.                      Xeric                                                 56/80            American burning), Oregon white                activity, pastureland, nursery crops.
      Vancouver Basin                                                                                                                                                                                                                                                                                                                                                                                                     
                                           wetlands, oxbow lakes and ponds.                     20-250         fault block basin.                                   (Xerochrepts, Fragiumbrepts),            Deep, silty clay loam to loam.                                                                                             oak, Douglas-fir, Oregon ash, alder,                                              
                                                                                                                                                                    Alfisols (Glossudalfs,                                                                                                                                              western red cedar.
                                                                                                                                                                    Haploxeralfs)