A linear ridge is a long hill or crest of land that stretches in a straight line.  It is possibly the result of fault motion (earthquakes) where there was prior uneven ground.  Higher ground (southwest of the fault) may have been moved in front of lower ground.  But there could be another explanation.  The southwest side of the fault may have been pushed upward by earthquakes, which created the ridge.

Upstream from this ridge, water and soil deposits have collected (scientists call this process ponding).  Ponding happens when all natural escape routes (or "drainages") for water have been blocked, as by this linear ridge.  The area has more vegetation than surrounding areas because it is supported by the trapped water.