GDAL Error - .grd not recognised as a supported file

Can anyone suggest the simplest way to get this data into R (I'm avoiding
the geotif due to bad internet and possible memory limitations on my PC)?

Given that its 20,000 by 10,000 pixels you might run into memory
limitations with any file format.

readGDAL(input_file)

Error in .local(.Object, ...) :
? ? ? GDAL Error 4: `C:/Users/Darren/Documents/ecology and
conservation/SP/data_gis/RASTEr/ETOPO1_Ice_g_gdal.grd' not recognised as a
supported file format.

Try this in R:

 GDALinfo(input_file)

 Since you are going to have trouble reading the whole dataset with
readGDAL, it might be easier to use the low-level GDAL functions to
sample from the whole thing. See help(GDAL.open) and
help(getRasterData) for more info.

Barry