Late Wisconsinan Wood and Other Tree Remains in the Presumpscot Formation, Portland Maine

[摘要] Well preserved tree remains have been discovered in glaciomarine clay of the Late Wisconsinan Presumpscot Formation at Portland,Maine. Logs,branches, cones,and needles occurred, just abovethecontact betweenthe clay and underlying gravel deposit. They were the first tree remains to be found inthe Presumpscot Formation. The radiocarbon ages of thelogs vary considerably, but their true age is believed to be between12,000 and 12,500 years. Specimens from the Portland locality are described in detail inthe present study. The logs and needles have been identified as spruce,and the associated cones indicate that the species is white spruce, (Picea glauca(Moench) Voss). The concentration and degree of preservation of the remains suggest alocal source - possiblythe nearbyhills that were above sea level inlate-glacialtime. The occurrence of the spruce logs in Portland also indicates thattrees may have colonized southwestern coastal Maine very soon after the retreat of LateWisconsinan glacialice from this area.

[学科分类] 地质学