30 Undergraduate Research: In Honor of Mike Higgins (Posters)

Friday, 1 April 2016
8:00 AM - 5:30 PM
Exhibit Hall

FRENCH BROAD RIVER TERRACE DEVELOPMENT IN THE CITY OF BREVARD, TRANSYLVANIA COUNTY, NORTH CAROLINA

Paper number: 30-26
Program: Theme Sessions
Time: 8:00 AM – 5:30 PM

Authors

Abstract

The French Broad River established its meandering course along the Brevard Fault Zone through Transylvania County, North Carolina creating a river valley that is approximately 2 km wide. The City of Brevard was built on a series of erosional, usually unpaired, terraces cut by ancestral river meanders into a thick pile of Quaternary sediments that filled the northwest side of the valley. This work attempts to establish the sequence of events in the development of the city site.

At least 4 ancient meander channels sculpted most of the stepped terraces seen in Brevard below the upper terraces in the city’s downtown area. The Jumping Branch Meander, on the southeast side, cut the 3-terrace system from the high school area across the city to its northwest side. We divide the terrace sets into the Forest Hills Terraces along the northwestward-flowing portion of the meander and the Turnpike Terraces for the southeastward-flowing part. The Jumping Branch tributary Duckworth Channel, flowing out of Pisgah National Forest, on the west, was eventually captured by Nicholson Creek It initially contributed to Turnpike terrace development and subsequently to Forest Hills terrace cutting after capture took place.

The Outland Channel carved a meander through the eastern neighborhoods and established the broad surface on which Brevard College is located. It was later breached by the College Meander, on the north, that formed the terrace surfaces that comprise the College athletic fields. Finally, the Gallimore Meander, of which little remains, removed the south bank of the Outland Channel at the junction of US 276 with Elm Bend Rd and Parkview Ave. Since the Gallimore event, the French Broad River has largely confined its course to the east side of the valley in the Brevard area.

The highest and steepest scarp in the city is present on the east side of Park Ave. and climbs above the south side of E. Main St. It extends westward between E. Main St. and French Broad St. and developed as the ancestral Outland Channel migrated across the northern flank of the city.

Results of this mapping project suggest that a long interval when deposition was the dominant mode in the French Broad River Valley, probably during the Wisconsinan ice advance. Lateral erosion and rapid meandering became the dominant mode after the present humid climate became established.

Geological Society of America Abstracts with Programs. Vol. 48, No. 3

doi: 10.1130/abs/2016SE-273798

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