Grinnell Formation henrymowry 12 years ago The rocks of the Grinnell Formation contrast beautifully with the water in Montana’s Glacier National Park. Tweeted by the US Department of the Interior, 9/16/14. Share this: Email a link to a friend (Opens in new window) Email Share on Facebook (Opens in new window) Facebook Share on Pinterest (Opens in new window) Pinterest Share on X (Opens in new window) X