Late glacial history of central Aroostook County, Maine: The younger Dryas problem
- Univ. of Maine, Orono, ME (United States). Inst. for Quaternary Studies
Previous work in Nova Scotia and New Brunswick, Canada has proven that a late-glacial climatic oscillation expressed itself in North America. Despite physical and palynological evidence in Canada for an event centered on the Alleroed-Younger Dryas chronozones, little conclusive evidence has been found for an equivalent oscillation in Maine. The only physical evidence for an Alleroed-Younger Dryas event so far in Maine is a deformed peat layer within a diamicton near Oxbow. Newman et al. reported ages on the peat ranging from 10,395 [plus minus] 85 to 11,760 [plus minus] 145 [sup 14]C yrs B.P. New excavation of the site in 1992 did not reveal the peat. Newman et al. reported a strong NNW-SSE stone fabric in the diamicton, which is consistent with regional flow directions and suggests that the diamicton may be a till. Regional basal organic [sup 14]C dates suggest that the area was ice-free by Younger Dryas time. The authors strategy for trying to solve this problem has been to investigate the stratigraphy of the Oxbow region, in conjunction with ice-flow directions as determined by bedrock striae and till fabrics. Ongoing fieldwork has shown that the direction of strongest bedrock erosion records a Late-Wisconsin ice flow event which occurred along a mean trend of s26E, based on 261 striation measurements at 36 localities. The NNW-SSE-trending striae cross-cut a W-E set at some localities. Faint striation sets which cross-cut the NNW-SSE-trending striae have no consistent orientation. This is in agreement with the striation data. A major drag fold found at the contact between the surface till and underlying gravel also indicates ice flow from the NNW (fold axis trend:s66W). The surface till has not been dated directly. The genesis of the diamicton at Oxbow and its relationship to the regional surface till remains unclear.
- OSTI ID:
- 5879236
- Report Number(s):
- CONF-9303211-; CODEN: GAAPBC
- Journal Information:
- Geological Society of America, Abstracts with Programs; (United States), Vol. 25:2; Conference: 28. annual Geological Society of America (GSA) Northeastern Section meeting, Burlington, VT (United States), 22-24 Mar 1993; ISSN 0016-7592
- Country of Publication:
- United States
- Language:
- English
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