Geology and Geomorphology

The geomorphic conditions at Carkeek Park tell the story of glaciation around the Puget Sound region. The Vashon Ice Sheet started melting about 50,000 years ago, receding and form Lake Russell in the Pleistocene time period. At the glacier receded, Piper’s Creek and the adjacent drainage system developed from the outwash plain. Plants did well in the region long ago, as evidenced by the peat bogs and low relief topography. When Piper’s Creek was still young, it cut a V-shaped valley into the region, draining the marshy uplands and cutting through the Vashon glacial till, revealing the underlying pre-Vashion Salmon Springs claystone and mudstone soil complex. Sea levels rose from the ice age melt off in the Post=Pleistocene era, so the ability for the creek to cut a ravine was reduced and a small delta formed where the creek enters the Puget Sound. The delta has increased in size since cedar logging operations contributed more eroded material in the early 1900s. As the size of the delta continued to increase and the creek bed matured, water started to cut laterally in constantly changing channels in a flattened valley floor because of the damming effect caused by the construction of a railway roadbed. Later, when a sewage treatment plant was installed in 1949, the feeder sewers led to washouts and pipe breaks, polluting the water and “urbanizing” the creek. Looking from the beach near the delta, you can see the southern tip of Whidbey Island, the Kitsap Peninsula, and the Olympic Mountains (History: Carkeek Park).