Interpretive Sign - The Silent City

The people of Green River call this the Silent City, a jagged cityscape formed by a great rock wall, the San Rafael Reef. You are about to enter and cross the San Rafael Swell, a large anticline where the earth’s crust has been heaved from below to form a great dome of rock layers. Erosion, over millions of years, has erased the top of the dome. Imagine a rainbow with a rough and ragged flat top where every band of color is revealed. Here, at the eastern edge of the anticline, erosion has sliced and sculpted the steeply tilted layers of hard sandstone. Slot canyons, spectacular pour-offs, sheer cliffs, and miles of desert varnish remain. Exploring the San Rafael Swell off I-70 can be fascinating but dangerous to the novice. Be sure you have plenty of water, gasoline, food, and a reliable map. Hiring a guide is recommended. For traveler information contact 1-888-654-3600.