A Holocene Coastal Soil Chronosequence, Graham Island, British Columbia, Canada.

Holocene evolution of the northeastern coastline of Graham Island (Haida Gwaii / Queen Charlotte Islands, British Columbia, Canada) has created a complex pattern of beaches, foredunes, raised marine platforms and estuaries.  These features have formed through the interaction of declining relative sea levels, aeolian activity, and coastal erosion that have modified the extensive glacial outwash deposits of the Argonaut Plain.  Recently published optical dates on the predominantly sandy sediments comprising these features range up to 6500 ± 500 BP.   The soils developed on these landforms constitute the longest chronosequence documented on the British Columbia coast, providing new evidence for rates of soil formation in this cool maritime environment (mean annual temperature ca. 8ºC; mean annual precipitation ca. 1200 mm).  Podzolization occurs rapidly – distinct eluvial horizons are evident after ca. 300 years and thicken progressively, accompanied by cementation of B horizons after ca. 2700 years.  These trends are accompanied by thickening of forest floors, creation of perched water tables, and the onset of bog formation on most level sites. This shift from podzolization to paludification resembles pedogenic trends documented previously in southeastern Alaska.  The survival of adjacent remnants of late Quaternary outwash as isolated interfluves potentially extends the duration of this chronosequence to as much as 20,000 years.