1. http://www.ngs.noaa.gov/GRD/GPS/Projects/CB/SUBSIDENCE/subsidence.gif http://www.msstate.edu/dept/geosciences/CT/TIG/WEBSITES/LOCAL/Summer2003/Buffington_Deborah/sinkhole.jpg Subsidence sinking of ground surface (vertical deformation) Rates can vary (collapse to gradual) Caused by removal of subsurface fluids (oil, ground water, steam, gas) or solids (limestone dissolution, coal, salt)

2. Karst Typical karst topography developed on carbonate bedrock in Russell County, VA Valley & Ridge province. From Lebanon 7.5' topographic map. http://www.wm.edu/geology/virginia/karst_topography.html http://www.env.duke.edu/eos/geo41/gw2.htm

4. http://capp.water.usgs.gov/gwa/ch_b/gif/b094.gif Ground water “mining” http://ga.water.usgs.gov/edu/graphics/mapsubsidence.gif http://www.extension.umn.edu/distribution/cropsystems/components/3115s01.html

5. http://capp.water.usgs.gov/gwa/ch_e/E-coastal_low5.html

6. subsidence from mining subsurface coal http://www.ohiodnr.com/geosurvey/geo_fact/geo_f12.htm

7. http://ga.water.usgs.gov/edu/earthgwlandsubside.html http://www.ohiodnr.com/geosurvey/geo_fact/geo_f12.htm

8. http://www.youtube.com/watch?v=dHol4ICeDoo Lake Peigneur, LA – salt mine collapse History Channel footage

9. http://www.oca-arb.co.uk/img/trs_clip_image002.jpg http://geochange.er.usgs.gov/sw/changes/anthropogenic/subside/ recognizing subsidence at your site