GEOLOGIC MAPPING IN LANCASTER, PA, USING CIR AND LIDAR

A 25 square kilometer region between Mountville and Lancaster, PA, has been mapped as folded layers of the Kinzers, Antietim, Vinatge, and Conestoga formations. Some limbs appear to be truncated by faults rather than complete folds. By combining LiDAR obtained by USGS (2005), and CIR imagery obtained by Lancaster County GIS (1999) and PA Bureau of Topographic and Geologic Survey (2002), it was possible to complete the mapping to show a large anticline. The CIR data were acquired during times of drought and therefore show geobotanical anomalies helpful in geological mapping. The LiDAR, presented as a shaded relief image, showed a geomorphic expression of the folding.

The use of GIS with LIDAR and imagery data allows geomorphic expression to be seen in 3D visualizations and aids in mapping geology in vegetated terrain. Since 2003 the Pennsylvania Geological Survey has been acquiring orthoimagery and digital topographic data state-wide as part of The National Map, known as PAMAP. The advent of PAMAP in Pennsylvania means that 1' imagery and 1.4m LiDAR state-wide will be freely available for download. The western third of the state now has LIDar coverage which will become available in 2006-2007. The entire state has now been covered with true color orthoimagery. Beginning in 2007, digital four band imagery (3 visible, one infrared) will be acquired. This opens up many new opportunities for revising geologic maps, as subtle geomorphic expressions can be used to heavily vegetated regions.