Idaho geologic map gets update

LEWISTON – The Idaho Geological Survey has released its first new geologic map of the state since 1978.

The 36-inch by 48-inch map became available for sale Friday. It’s a shaded relief map that uses 75 colors to identify geological formations, different varieties of rocks and their ages.

“It’s really a piece of art,” Idaho Geological Survey Director Roy Breckenridge told the Lewiston Tribune. “You don’t have to be a geologist to be drawn to it. It encourages inquiry and discovery of the land we live in.”

Breckenridge said Idaho rocks haven’t changed much since the 1978 map, but a lot of new mapping has been done that adds information to the most recent map. And he said technology has also increased the ability to date rocks, making the map more accurate in dating geologic formations.

“Technology allows us to learn more about the geological underpinnings of the state,” Breckenridge said. “Geologists have an interpretive view of our surroundings, and the interpretations change with modern technology. The geological record is more complete in some places than others. That’s part of the beauty of Idaho. It’s at the juncture of a number of interesting geological provinces and has a relatively complete record from about 2.6 billion years onward.”

Keegan Schmidt, a geology professor at Lewis-Clark State College, said geologic maps have storytelling elements.

“It starts the first day at the first outcrop,” Schmidt said. “You walk up to a rock and mark its location on a map. That rock represents an event.”

The Idaho Geological Survey, created in 1919, published its first geological survey map in 1947, followed by the 1978 map, and now by the latest version.