sentences:  Another 77 peaks fall between .Climbs range in difficulty between the Observation Peak, a Class 1 hike, and King Spire, a rock route rated Class 5.10 on the Yosemite Decimal System.The northern Sawtooth Range formed from the Eocene Sawtooth batholith, while south of Alturas Lake the mountains formed from the Cretaceous granodiorite of the Idaho Batholith.