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)                                                                                      


3c.  Prairie Terraces          1971 Nearly level to undulating fluvial terraces with           160-500         Pleistocene lacustrine and fluvial                   Alfisols (Albaqualfs), Mollisols  Woodburn, Aloha, Willamette,                              Mesic/             40-50           165-210             33/46;           Oregon white oak, prairies                     Grass seed, grain farming (often on reclaimed
                                           sluggish, meandering streams and rivers.                 /          sedimentary deposits.                                (Argialbolls, Argixerolls),              Dayton, Amity, Concord, Malabon,                    Xeric                                                 51/85            (maintained by Native American                 wetland). Also urban/rural residential
                                           Historically, seasonal wetlands and ponds were       10-150                                                              Inceptisols (Xerochrepts)                Coburg, Salem. Very deep to deep,                                                                                          burning). In wetter areas: Oregon              development and some forested riparian zones.
                                           common. Many streams now channelized.                                                                                                                             silty clay loam to silt loam.                                                                                              ash, Douglas-fir.