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Abstract Detail


Paleobotanical Section

Stults, Debra [1], Axsmith, Brian [2].

Late Pleistocene fossil plants within a Mobile River terrace near Mount Vernon, Alabama.

A newly-discovered Pleistocene fossil plant locality within the Mobile-Tensaw Delta in southwest Alabama is producing abundant macrofossil remains of Liquidambar, Nyssa, multiple Carya species, multiple Quercus species, Betula, Carpinus, Pinus, and other taxa. Many of the most well-preserved specimens are fruits, although leaves and rhizomes have also been recovered. Identifications are preliminary, but so far the collection appears to consist of extant genera and species. Sufficient quartz and feldspar minerals were present, allowing the fluvial fossil-containing sediments to be candidates for optical luminescence dating. The ages obtained from both minerals are very similar and indicate the plant fossils are approximately 83,000 yr BP in age. This is significant, as these Mobile River Pleistocene plants are older than the upper age restrictions of 14C dating, and plant finds of this age are very rare in the southeastern United States. The Mobile River is in the northern portion of the Mobile-Tensaw Delta valley. Even though this area is commonly referred to as a delta, apparently the more correct terminology for its particular geography is ‘drowned alluvial plain and valley’. There are geological records of many fluvial terraces and a couple of marine terraces in this region, obvious evidence of marine base level modifications occurring many times during the Pleistocene in accordance with oscillating changes in climate and global glacial cover. The chronology of these fluvial terraces is poorly understood. However, the important recovery of these fossil plants, and the need for dating them, has led to a dependable dating of this particular fluvial terrace.


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1 - University of South Alabama, Department of Marine Sciences, Life Sciences Bldg 25, Mobile, Alabama, 36688, USA
2 - University of South Alabama, Biological Sciences, Life Sciences Building 124, Mobile, AL, 36688, United States

Keywords:
Pleistocene
fluvial terrace
Mobile-Tensaw Delta
optical luminescence dating.

Presentation Type: Oral Paper:Papers for BSA Sections
Session: 71
Location: Superior A/Cliff Lodge - Level C
Date: Wednesday, July 29th, 2009
Time: 2:45 PM
Number: 71003
Abstract ID:109


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