 A trail north of the Union Pacific tracks (the Sullivan's Gulch Trail) is in planning, but has been held up by its estimated price of $36 million plus land acquisition costs.The gulch itself was formed between 15,000 and 13,000 years ago at the end of the last ice age when the ice dam containing Glacial Lake Missoula thawed some 40 times, causing some of the largest floods known on earth.The flood waters spilled across Idaho and eastern Washington, surged down the Columbia River and through the Gorge, flooding the Willamette Valley as far south as Eugene.