Timing and climatic controls over Neoglacial expansion in the northern Coast Mountains, British Columbia, Canada.

Holocene sedimentary records from two lakes in White Pass, British Columbia, show that the onset of Neoglacial sedimentation began c. 2 ka cal. BP. Prior to this time, the lakes accumulated organic-rich sediments, with properties and sedimentation rates similar to adjacent lakes that have not had glacial influences during the Holocene. Neoglaciation at White Pass was coincident with the increased delivery of exotic Tsuga heterophylla (western hemlock) pollen. These results, together with regional indications for increased delivery of hemlock pollen at 2 ka BP by a deepened low pressure in the northeastern Pacific Ocean, suggest that increased moisture was important for the expansion of glaciers in the region in addition to longer-term late Holocene cooling. [ABSTRACT FROM AUTHOR]