Cinnabar

Yellowstone National Park History: Before 1903, trains would bring visitors to Cinnabar, Montana, which was a few miles northwest of Gardiner, Montana ...

A view from 1939:

The DEVIL'S SLIDE, 51 m., an exposed dike of bright-red iron-impregnated rock on Cinnabar Mountain, is (R) across the river. The mountain was named by early settlers who thought the red rock was cinnabar. The legend of the Devil's Slide is told in a jingle:
" Ages ago, one can easily see, Old Yellowstone Valley went on a spree; The mountains had risen, the valleys had sunk, And old Mother Nature got roaringly drunk. The Devil, as drunk as the Devil would be, Slid to the bottom of Cinnabaree."

Source: Montana: A State Guide Book; Compiled and Written by the Federal Writers' Project of the Work Projects Administration for the State of Montana; September, 1939.