Road trip to Kemmerer, Wyoming (an easy drive from Park City or Salt Lake City) where you can DIG FOR 50 MILLION YEAR OLD FISH FOSSILS. It's hugely fun for the whole family. http://www.travelsavvymom.com/blog/family-travel/digging-for-fossils-in-wyoming/
Great Basin National Park Great Basin National Park Millard County is considered by some to be the eastern gateway to Great Basin National Park. From the sagebrush at its alluvial base to the 13,063-foot summit of Wheeler Peak, Great Basin National Park includes streams, lakes, alpine plants, abundant wildlife, a variety of forest types including groves of ancient bristlecone pines.