Anders Family
David Asbel Anders with
Jim and Tina Smith Anders
Family

US GenWeb Project

Rufus and Florence Hall Owen Family in 1947
Rufus and Florence Hall Owen and children

US GenWeb Archives Project

 

Transylvania County, NC 

GenWeb Project

NC GenWeb

 

Lake Toxaway Dam Breakage of 1916

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The following images were included in a MS PowerPoint presentation used by North Carolina Geological Survey geologists from the Asheville Regional Office at many public landslide outreach meetings. The presentation has been adapted to the Internet for broader distribution. This page is on "Rock Slope Stability."

LTDB1
Landslides and landslide related fatalities from the mid-July 1916 hurricane in Transylvania County, NC. Damage from landslides and flooding occurred over much of the south-central mountain area. The July 15-16, 1916 flood is considered the flood of record in western North Carolina.

LTDB2
Color-infrared aerial photograph of the Gorges State Park area, Transylvania County, North Carolina showing mapped locations of deposits left by the catastrophic failure of Lake Toxaway Dam on August 13, 1916. The dam failure triggered a debris flow along the Toxaway River that traveled over 7 miles and into South Carolina. Lake Jocassee is underlain by cobble, gravel and sand deposits from the flood. The original dam was in about the same location as the current dam. The quote shown is from S.W. McCallie, State Geologist of Georgia at the time. Studies by the North Carolina Geological Survey estimate that the outflow just below the dam was on the order of 293,938 cfs (discharge) and 50 mi/hr (velocity). Information from Geology of Gorges State Park, N.C. Geological Survey Information Circular 31.

LTDB3
Top: View looking downstream along the Toxaway River below the dam showing the assumed scour lines and the location of cross section D (bottom) used to reconstruct the super elevation angle of the dam failure torrent. This information goes into computing an estimated velocity and discharge of the outflow.

LTDB4
Top Left: 60-foot long boulder weighing nearly 900 tons transported by the flood waters along the Toxaway River from the August 13, 1916 Lake Toxaway Dam failure. Photograph taken about 0.5 miles downstream from Toxaway Falls. Top Right. Imbricated boulders at the crest of the boulder levee shown in red in the cross section at Bottom Left. Bottom Right. Photograph of the contact (shown by arrow) of the boulder flood deposits overlying pre-existing flood plain deposits along the Toxaway River.

LTDB5
Left: Detailed map of a ~4 acre active weathered-rock slide along the Toxaway River in Gorges State Park. This slow-moving landslide was probably triggered by the 1916 dam failure torrent that eroded and over-steepened the slope along the river. Right: Tree ring studies of trees on and off the slide indicate a period of slide movement during the 1965-1974 timeframe corresponding to a period of above average rainfall. Tree ring studies were done cooperatively with the U.S.F.S. Coweeta Hydrologic Laboratory, Otto, N.C. Information contained in Geology of Gorges State Park, N.C. Geological Survey Information Circular 31.

LTDB6
Trees growing on an active landslide are commonly curved. The tree tilts with the moving slide, and over time attempts to regain vertical growth resulting in the curved trunk. A and B. Curved trees showing the effects of movement on the Toxaway River weathered-rock slide. White arrow points to person for scale in photo A (left).

LTDB7
Field developed cross section view of the Toxaway River weathered-rock slide in Gorges State Park. Information contained in Geology of Gorges State Park, N.C. Geological Survey Information Circular 31.

LTDB8
Left: Example of landslide hazard mapping. Slope movements (landslides), flood and other surficial deposits mapped in Gorges State Park by the N.C. Geological Survey.

Right: Bedrock geologic map of Gorges State Park. Mapping landslides and surficial units along with bedrock provides the best geologic framework for constructing landslide hazard maps. Information contained in Geology of Gorges State Park, N.C. Geological Survey Information Circular 31.

Center: Schematic block diagram showing the relationships between bedrock structure, streams, and slope movements for Gorges State Park, Transylvania County, N.C.

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For additional information about landslide hazards in North Carolina, please contact Mr. Richard Wooten with their Asheville Regional Office:

2090 U. S. Highway 70,
Swannanoa, North Carolina 28778.
828-296-4632
http://www.geology.enr.state.nc.us/Default.htm
Rick.Wooten@ncdenr.gov