reading .grd files

Hello all,

I  downloaded a .grd file from
http://pubs.usgs.gov/of/2005/1413/gisdata/data/NAMrad_U.grd and would
like to open it in R. Can anyone please tell me how to open .grd type
files in R. I tried to read with raster, ncdf and also rgdal, but couldnt.

A little exploration leads me here:

http://pubs.usgs.gov/of/2005/1413/gisdata/data/readme.txt

which tells me that file is a 'GeoSoft Grid' format file (note - the
.XXX part of a file is no guide of its true content).

And sadly that seems to be a proprietary format that only GeoSoft can
read. There are GDAL drivers for GeoSoft's exchange format (GXF files)
but not these grid files.

You could try GeoSoft's Oasis Montaj Viewer (free download) which
might be able to export them to something else:

http://www.geosoft.com/support/downloads/viewers/oasis-montaj-viewer?dnld=333

Or you could contact the authors and ask them to make their data
available in an open format...

Barry