Masters Theses

Date of Award

6-1986

Degree Type

Thesis

Degree Name

Master of Science

Major

Geology

Major Professor

Paul A. Delcourt

Committee Members

Richard Arnseth, Thomas Broadhead, Hazel Delcourt

Abstract

Paleoecological analysis of a 2.3 m sediment core from Big Run Bog, Tucker County, West Virginia (39° 07'N, 79° 35'W), provides an integrated and continuous record of vegetation change for the Allegheny Plateau of the central Appalachians for the past 17,000 yr from the full-glacial conditions of the Wisconsin through Holocene. Big Run Bog (980 m elevation) is high-elevation wetland within the Allegheny Mountain section of the Appalachian Plateaus physiographic province.

From 17,040 yr B.P. to 13,860 yr B.P. the plant communities surrounding the site were a mosaic of alpine tundra dominated by sedges (Cyperaceae) and grasses (Gramineae) with total pollen accumulation rates averaging 1158 gr·cm-2.yr-1. By 13,860 yr B.P., late-glacial climatic warming as well as an increase in effective available moisture allowed the migration of spruce (Picea) and fir (Abies) onto the plateau, and favored the concurrent increase in colluvial activity within the watershed of Big Run Bog. From 13,860 yr B.P. to 11,760 yr B.P., continuing episodes of colluvial activity and the instability of the montane landscape may have inhibited initial colonization and the eventual closing of the boreal forest, despite favorable climatic conditions. The period from 11,760 yr B.P. to 10,825 yr B.P. was a period of landscape stabilization, a changeover from colluvial to fluvial processes, and a fundamental change in clay mineralogy.

The boreal forest in the uplands surrounding Big Run Bog was displaced by a mixed conifer-northern hardwood forest by 10,500 yr B.P., with oak (Quercus), birch (Betula), and hemlock (Tsuga) comprising the upland dominants. Through the period from 8190 yr B.P. to 115 yr B.P., upland forest were dominated by of oak, birch, and chestnut (Castanea). Spruce persisted around the bog margin in selected ravine and ridgetop habitats. Extensive logging between 1880 and 1920 AD is documented in the plant-fossil record by an increase in disturbance-related taxa such as ragweed (Ambrosia type) and grasses and the decline in local populations of spruce, chestnut, and hemlock.

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