The bedrock geology of the 7.5-minute Windham quadrangle, New Hampshire
consists of deformed early Paleozoic crystalline metamorphic and intrusive
igneous rocks intruded by Mesozoic igneous dikes.
The geologic data was mapped during the summer of 1998 at a scale of
1:24,000. The bedrock geology was mapped using standard techniques.
Locational information was provided by Rockwell PLGR+96 GPS receivers
using the federal precise positioning service.
The line and polygon data were compiled on a mylar greenline of the
7.5-minute quadrangle and scanned at 400 dpi on an Anatech Eagle 4080T
scanner. The raster files (TIF) were converted to vector files (DXF)
using GTX OSR version 2.0 raster-to-vector conversion software. The
vector files were imported to Arc/Info version 7.0.4. Point data
were collected with GPS and hand-held 3COM Palm Pilot III PDA computers.
Data from the PDAs were combined in Microsoft Access, and then imported
as ASCII text files and DBASE IV (dbf) files into Arc/Info. The Arc/Info coverages
were registered and transformed to the New Hampshire State Plane Coordinate
The map was published as part of a study of the fractured bedrock aquifers
in the state of New Hampshire. The digital data are intended for use by
all government, academic, commercial, or other agencies in need of digital
geologic map information.
Currentness_Reference:The geology of the quadrangle was mapped in 1998