Some 70 million years ago the magma of the Boulder Batholith rapidly cooled underground. The rapid cooling in conjunction with high water content resulted in fractures which formed pathways for water to carry metals in a solution throughout chunks of a block of igneous rock 70 by 40 miles in size. Veins of riches and precious metals produced by this process were early catalysts of prosperity for Butte and Helena. In essence, the Boulder Mountains gave birth to modern-day Montana.
But until very recently, this mountain range had no name.
Since 1890, The U.S. Board of Geographic Names (USBGN), a federal body under the Department of Interior, has established and maintained the official place-names of the geographic features of our country. In his superb book, “This is Montana,” Rick Graetz, the great Montana geographer, refers to the mountains between Lincoln and Butte as the “The Unnamed Mountains.” This is only half correct.
