• The global SRTM digital terrain model and AW3D30 digital surface model are used to map and describe folds
  • Structural controls on cave passage orientation are revealed
  • Discoveries are made in very gently folded strata dipping <5o
  • Evaluation site characteristics indicate potential for wide use


A novel method to map and quantitatively describe very gentle folds (limb dip <5o) at cratonic cave sites was evaluated at Snail Shell and Nanna Caves, central Tennessee, USA. Elevations from the global SRTM digital terrain model (DTM) were assigned to points on late Ordovician geologic contacts, and the elevations of the points were used to interpolate 28 m cell size natural neighbor digital elevation models (DEM’s) of the contacts. The global Forest Canopy Height Dataset was subtracted from the global 28 m cell size AW3D30 digital surface model (DSM) to create a DTM, and that DTM was applied in the same way. Comparison of mean and modal strikes of the interpolated surfaces with mean and modal cave passage trend show that many passages are sub-parallel to the trend of an anticline. Within 500 m of the caves, the SRTM- and AW3D30-based interpolated surfaces have mean strikes within 8o of the mean strike of an interpolated reference surface created with a high resolution (~0.76 m cell size and 10 cm RMSE) Tennessee, USA LiDAR DTM. This evaluation shows that the SRTM- and AW3D30-based method has the potential to reveal a relationship between the trend of a fold, on one hand, and cave passages, on the other, at sites where a geologic contact varies in elevation by >35 m within an area of 2 and the mean dip of bedding is >0.9o.



Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 4.0 License.

Appendix 1.pdf (62 kB)
Appendix 1. Python script 1

Appendix 2.pdf (58 kB)
Appendix 2. Python script 2

Appendix 3.pdf (159 kB)
Appendix 3. Structural data

Abolins_Ogden.ris (1 kB)