Early Holocene lake sediments are exposed near Fauquier, on the east side of the Arrow lakes in the Columbia River valley of British Columbia. A glacial lake occupied the valley at the time of deglaciation, but by 10 ka BP this had been replaced by a nonglacial lake that was at least 250 km long and as much as 5 km wide.Comparison of pollen and macroscopic plant remains in these nearshore and littoral deposits with modern vegetation indicates that many of the plants present between 9 and 10 ka BP are found in the area today, either along the valley floor or at higher elevations in the subalpine zone nearby. Some of the organic material may be allochthonous; this complicates paleoecological and paleoclimatological interpretations. It appears that the climate in the Columbia River valley between 9 and 10 ka BP was as wet or wetter than at present. The presence of many of these species in the southern Columbia River valley of British Columbia during early Holocene time suggests that elements of the modern vegetation had migrated rapidly northward from southern refugia, probably within 1500 years of the end of the last glacial episode.

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