Although trappers and prospectors who visited the Yellowstone region had knowledge of the canyon, the first significant descriptions were publicized after the Cook�Folsom�Peterson Expedition of 1869 and the Washburn-Langford-Doane Expedition of 1870.
When Charles W. Cook first viewed the canyon after traveling west from the Lamar Valley on September 20, 1869 he subsequently wrote these words in his journal:
I was riding ahead, the two pack animals following, and then Mr. Folsom and Mr. Peterson on their saddle horses. I remembered seeing what appeared to be an opening in the forest ahead, which I presumed to be a park, or open country. While my attention was attracted by the pack animals, which had stopped to eat grass, my saddle horse suddenly stopped. I turned and looked forward from the brink of the great canyon, at a point just across from what is now called Inspiration Point. I sat there in amazement, while my companions came up, and after that, it see...