Idaho Rocks!

Book excerpt: To discover the unworldly geologic novelties of the Gem State, all that is required is a good map, a sense of adventure, and Idaho Rocks!, a guide to 60 of the most compelling geologic sites in Idaho. The well-chosen destinations span the state's geologic history from the 2.6-billion-year-old gneiss in the Panhandle to 2,000-year-old lava at Craters of the Moon, and from gold and silver deposits hidden in Idaho's mountains to visible scars from recent earthquakes and landslides. With its beautiful photographs and informative figures and maps, this guidebook will get you up to speed on every aspect of Idaho's diverse geology. Northern and central Idaho's sparkling rivers flow past algal mounds in 1.4-billion-year-old limy sediments, sandy beaches eroded from crystalline granite, and exotic rocks of ancient volcanic islands. Southern Idaho has been shaped by calderas of the Yellowstone hot spot, along with active faults of the Basin and Range, and one monumental flood that carried boulders the size of cars. Rock hounds can search for star garnets along Emerald Creek, zeolite crystals in basalt cavities, and eye-shaped feldspar in ancient gneiss. Fossil enthusiasts can discover leaf imprints at Clarkia Fossil Beds, learn about Pliocene horses at Hagerman Fossil Beds, and contemplate the bizarrely whorled teeth of the buzz saw shark who prowled the sea 290 million years ago when Idaho's phosphate deposits were accumulating.