GDA (Geologic Data Assistant) is an extension to ArcPad, a mobile mapping software program by Environmental Systems Research Institute (ESRI) designed to run on personal digital assistant (PDA) computers. GDA and ArcPad allow a PDA to replace the paper notebook and field map traditionally used for geologic mapping. GDA allows easy collection of field data.
Additional publication details
USGS Numbered Series
GDA (Geologic Data Assistant), an ArcPad extension for geologic mapping: code, prerequisites, and instructions
Pacific Northwest Geologic Mapping and Urban Hazards