At tree line, the trees are reduced to krummholz, battered and twisted by wind and frost. The bristlecone pine grove on the east slope of Mount Goliath () contains at least one tree that sprouted in the year 403 AD. For many years, these were the oldest known trees in Colorado, but in 1992, trees dating to 442 BC were found in the southern Front Range and South Park. The Mount Goliath Natural Area, jointly managed by the United States Forest Service and the Denver Botanic Gardens protects this grove of old trees.