One of most impressive drives in state is Texas 207 south toward Silverton. For miles agricultural riches spread from horizon to horizon; then the highway plunges into scenic grandeur at Palo Duro Canyon. Descend at a moderate speed, both for safety and to absorb beauty that unfolds in a riot of colors. In the nine-mile-wide canyon (which extends a hundred miles from northwest to southeast) is the Prairie Dog Town Fork of the Red River, a seemingly insignificant stream to have carved such an immense gash in the Plains. Farther south the highway drops into another beautiful gorge, Tule Canyon. More varieties of rock strata are visible, and some magnificent sheer-faced, knife-edged buttes.