Terrific gravel biking routes abound around Great Falls. From exploring the wheat desert to the north of town to the foothills and mountains to the east, south and west of town, opportunities abound. A few ideas below. More ideas (and gpx files) at gravelmap.com . (Thanks Brian Stremcha!)
Ulm Bench (northwest of Ulm)
Comer’s Butte Loop (east of Belt)
Cascade 29 (east of Cascade)