When I was developing two years ago I altered the GPS settings on the device and they started outputting .txt files to the SD card. This made no sense to me and after looking into it if an application installed has this issue it will persist until the application is removed. I can not remember the folder location.
I want to say /sdcard/gps/* but here is a reference if this was the issue: SD Card fills up with GPS/*.txt filesSD Card fills up with GPS/*.txt files