Dedicated 3D graphics converters like the 3D Object Converter program support large number of various formats, including the GEO and ASC files. Should be easy enough to perform this conversion using that or other similar program.
Convert VRML geography data to 3D Studio Max 3D ASCII scene.
We have found one software suitable in our database for this conversion.
Microsoft Windows software - convert geo to asc on Windows
3D viewer and converter with huge file type support
Convert from geo file format
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.