Читать книгу Backpacking Arizona. From Deep Canyons to Sky Islands онлайн

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After crossing Horse Canyon and a smaller, unnamed drainage, the trail turns to the north. Ahead, massive walls of salmon-hued Navajo sandstone mark the head of Dome Canyon. The trail contours above the head of this impressive canyon and then crosses a small, narrow ridge. Here it starts the steep descent into Cliff Canyon, plunging more than 1700 feet in 1.3 miles. Once the trail reaches the bottom of the canyon, watch for water in the bed. You may find a few pools along this section. Pick up water for a dry camp, and then look for a campsite as you continue downstream. Plan to camp before you reach the turnoff to Redbud Pass.

Natural Bridges

Natural bridges, such as Rainbow Bridge, are created when a stream erodes both sides of a meander. Much of the erosion in these desert canyons takes place during brief but violent floods caused by summer thunderstorms. The floodwater, containing sand, gravel, and boulders, gnaws away at the outsides of bends. Where a canyon loops back on itself, such erosion tends to cut through the narrowing fin of rock separating the two sides of the bend. When it succeeds, the stream takes the new shortcut, rapidly turning it into the main channel. Occasionally the top of the fin remains intact, bridging the new streambed. The underside of the stone bridge continues to erode away, mainly from weathering of the rock surface, and the size of the opening increases. Eventually, of course, the structure is weakened to the point of collapse. Geologically speaking, natural bridges are very short-lived formations.