Glen Canyon and Lake Powell are a National Recreation Area, and Rainbow Bridge is a National Monument. It is located in Utah, but only a few miles across the border from Arizona, so I always say they did not draw the state line correctly and it should be in Arizona. The rocks are mostly Navajo Sandstone.
Rainbow Bridge
Rainbow Bridge is a stunning natural geological formation located just north of the Arizona/Utah border. It is one of the largest natural bridges in the world. It stands 290 feet high and spans 275 feet across. The top of the arch is 42 feet wide and 33 feet thick.
Formation
Rainbow Bridge is a result of the erosional processes that shaped the sandstone landscape of the surrounding region. It was formed through the gradual cutting and shaping of the rock by flowing water.
The arch of the bridge is carved from Navajo sandstone, with its distinctive red and orange hues. This sandstone was deposited in ancient desert environments and then sculpted by the elements. The sandstone was formed in the late Triassic or early Jurassic.
Older Kayenta Sandstone forms the underlying base of the bridge.
Erosion
The primary agent of erosion forming Rainbow Bridge is water, specifically the flow of the Owachomo Creek. Over time, the creek cut through the sandstone it flowed over and around, creating a deep and narrow canyon.
Currently, there is no water under the bridge. When Lake Powell is full, some water is present, but no swimming is allowed.
Visiting
Due to its remote location, reaching Rainbow Bridge can be an adventure. Visitors often hike or take boat trips (where there’s water). The journey itself offers stunning views of the surrounding landscape.