The Subway, North Creek, Zion National Park, Utah

The Kayenta sandstone narrows along this section of North Creek have eroded into a tube similar in appearance to a subway tunnel. Named “The Subway”, the two parallel grooves along the center of the floor of this tube add to the effect. These hollowed-out sculpted alcoves can be found in many locations in Zion National Park where the Kayenta layer meets the overlying Navajo Sandstone layer. While the thick layer of porous Navajo Sandstone above allows water to migrate vertically down through the rock, it is forced out of the Navajo Sandstone when it encounters the more impervious Kayenta layer below. As this water seeps out of the canyon walls it causes the rock to erode and forms these alcoves. This same action created the alcove of the Weeping Wall along Zion Canyon.