An Investigation of the Origin of Rock City and Cause of Piping Problems at Mountain Lake, Giles County, Virginia
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Kent State University / OhioLINK
2013
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| Online Access: | http://rave.ohiolink.edu/etdc/view?acc_num=kent1382371064 |
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ndltd-OhioLink-oai-etd.ohiolink.edu-kent13823710642021-08-03T06:19:53Z An Investigation of the Origin of Rock City and Cause of Piping Problems at Mountain Lake, Giles County, Virginia Atallah, Nidal Walid Geology Geomorphology Environmental Geology Environmental Engineering Hydrologic Sciences Mountain Lake landslide dam Rock City lateral spread self-draining lake soil piping silty soil seepage lake-level fluctuations Mountain Lake is one of only two natural lakes in the state of Virginia. The lake's origin has been attributed to either a natural solution-collapse basin, or to a landslide damming the valley of northwesterly flowing Pond Drain, or to a NW-SE trending fracture lineation. The lake is located within the breached northwest limb of a gently plunging anticline, a part of the larger Valley and Ridge physiographic province. In recent years, the lake drained almost completely, exposing the lake bottom and revealing the presence of four sinkhole-like depressions, containing piping holes at their sides and bottoms, at the northeastern and northwestern margins of the lake. This study focuses on the most likely origin of large sandstone blocks present at the northern end of the lake in an area locally referred to as "Rock City", including mapping of the block locations and analyzing the mode and extent of displacement that they have undergone. An additional objective is to investigate the piping potential of the lake-bottom sediment and its role in seepage out of the lake basin causing lake-level fluctuations. Mapping of Rock City was conducted by taking GPS readings at the corners of the rock blocks and using ArcMap Software. Investigations of the displacement mode of the rock blocks was done by comparing the measured orientations of principal discontinuity sets, forming the rock-block boundaries, with discontinuity orientations of undisturbed outcrops within the headscarp, using stereonet analysis. Grain size analysis, Atterberg limits, and a compaction-mold permeameter test were used to evaluate lake sediment's susceptibility to piping.Field observations and discontinuity data analysis indicate that Rock City is a landslide that dammed the valley of Pond Drain, consequently forming the lake. The primary mode of slope movement involves lateral spreading that is associated with extension occurring along discontinuities. The Tuscarora Sandstone rock blocks comprising Rock City were detached from the scarp face along a northwest-southeast trending joint set and were displaced laterally towards the west. A seismic event appears to be the most likely triggering mechanism for slope movement.Laboratory testing reveals that lake-bottom sediment is susceptible to piping, which is the primary mechanism responsible for the formation of the lake-bed depressions and lake-levels fluctuations. Grain size analysis reveals that lake-bottom sediment consists predominantly of fine sand and silt, both of which are highly susceptible to piping. Results of the compaction-mold permeameter test show that the hydraulic gradient at which lake-bottom sediment starts to pipe, the critical hydraulic gradient, ranges between 1 and 10, depending on the density, grain size distribution and cohesive properties of the sediment. 2013-10-24 English text Kent State University / OhioLINK http://rave.ohiolink.edu/etdc/view?acc_num=kent1382371064 http://rave.ohiolink.edu/etdc/view?acc_num=kent1382371064 unrestricted This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws. |
| collection |
NDLTD |
| language |
English |
| sources |
NDLTD |
| topic |
Geology Geomorphology Environmental Geology Environmental Engineering Hydrologic Sciences Mountain Lake landslide dam Rock City lateral spread self-draining lake soil piping silty soil seepage lake-level fluctuations |
| spellingShingle |
Geology Geomorphology Environmental Geology Environmental Engineering Hydrologic Sciences Mountain Lake landslide dam Rock City lateral spread self-draining lake soil piping silty soil seepage lake-level fluctuations Atallah, Nidal Walid An Investigation of the Origin of Rock City and Cause of Piping Problems at Mountain Lake, Giles County, Virginia |
| author |
Atallah, Nidal Walid |
| author_facet |
Atallah, Nidal Walid |
| author_sort |
Atallah, Nidal Walid |
| title |
An Investigation of the Origin of Rock City and Cause of Piping Problems at Mountain Lake, Giles County, Virginia |
| title_short |
An Investigation of the Origin of Rock City and Cause of Piping Problems at Mountain Lake, Giles County, Virginia |
| title_full |
An Investigation of the Origin of Rock City and Cause of Piping Problems at Mountain Lake, Giles County, Virginia |
| title_fullStr |
An Investigation of the Origin of Rock City and Cause of Piping Problems at Mountain Lake, Giles County, Virginia |
| title_full_unstemmed |
An Investigation of the Origin of Rock City and Cause of Piping Problems at Mountain Lake, Giles County, Virginia |
| title_sort |
investigation of the origin of rock city and cause of piping problems at mountain lake, giles county, virginia |
| publisher |
Kent State University / OhioLINK |
| publishDate |
2013 |
| url |
http://rave.ohiolink.edu/etdc/view?acc_num=kent1382371064 |
| work_keys_str_mv |
AT atallahnidalwalid aninvestigationoftheoriginofrockcityandcauseofpipingproblemsatmountainlakegilescountyvirginia AT atallahnidalwalid investigationoftheoriginofrockcityandcauseofpipingproblemsatmountainlakegilescountyvirginia |
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