Angels Landing. Where the canyon pinches off in the middle of the photo is where The Narrows, a slot canyon, begins.
Why is there a rather-abrupt change from the slot canyon that is The Narrows to the quarter-to-half mile wide Lower Canyon? It all has to do with the rock layers. During the Mesozoic Era, the area that now encompasses Zion NP used to be a flat coastal plain. Most of the rocks in Zion were laid down during the Jurassic Period. Beginning in the Cretaceous Period, this entire region of the West experienced a period of uplifting, where the layers of rocks were slowly thrust upward to heights from near sea level to over 10,000 feet above sea level. The ancestral Virgin River, through the power of erosion, began to cut downward through these rock layers as the layers were uplifted. When the Virgin River arrived at what was to become Zion NP, it hit the massive layer of Navajo Sandstone (which is upwards of 2,200 feet thick). Sandstone is a rather hard rock which isn't easily eroded. Generally speaking, soft rocks form broad canyons and slopes when eroded, while harder rocks tend to form cliffs and slot canyons (A slot canyon is essentially a really narrow canyon that is deeper than wide). The Virgin River, trying to follow the path of least-resistance to the sea, cut straight down through the Navajo Sandstone Formation. This resulting deep, but narrow, canyon became known as The Narrows.
|Heading toward The Narrows.|
After the Virgin River cut through the entirety of the Navajo Sandstone Formation, it ran into the Kayenta Formation. The Kayenta Formation is a rather soft formation, and the Virgin River was able to erode a much wider canyon. The transition between The Narrows and the relatively wide Lower Canyon occurs at the transition between the hard Navajo Sandstone and the soft Kayenta Formation below it.
|Riverside Walk Trail (Left), Southern Maidenhair Fern, Adiantum capillus-veneris (Right)|
this Canyoneering USA link!
|Wall Street in The Narrows, with 1,500 foot canyon walls and the river reaching from wall-to-wall in most sections (I hiked in low water levels, so there's more exposed land than what there normally is).|
The National Park Service will close The Narrows to hikers if it seems a flash flood is potentially possible for that day. That doesn't mean that one can't pop up unexpectedly with no warning. Even if the sky is blue over The Narrows, a rain event out of sight at the headwaters can send a wall of water downstream. Be aware: if you hear a rumbling in the canyon, get to high ground. If the water begins to change color, get to high ground. If the water seems to be ever-so-slightly rising, get to high ground. Just be aware, and if it seems like it might be a bad day to do this hike, don't do it. Remember, in a national park your safety is your responsibility, not the National Park Service's.
Thanks for reading!