Final answer:
An upward arching rock layer can be a 'diapir,' where rock has moved upward into overlying strata, or a 'monocline' like the Waterpocket Fold in Capitol Reef National Park, formed from regional tectonic forces.
Step-by-step explanation:
An upward arching rock layer is typically referred to as a diapir or a monocline depending on its specific shape and formational process. A diapir is a domed rock formation where a core of rock, often of lower density such as salt or magma, has moved upward into the overlying strata. Alternatively, the Waterpocket Fold at Capitol Reef National Park is an excellent example of a monocline, which is a type of fold in the Earth's crust that resembles a step-up in rock layers and is often the result of regional tectonic forces. These forces were responsible for the uplift seen in the Colorado Plateau, altering ancient sedimentary layers that have been deposited horizontally. Zion National Park's rocks, which are mainly sedimentary, tell the history of the area's ancient environments. Another significant formation is the vertically faulted ancient sedimentary beds found at Garden of the Gods, Colorado, which demonstrates the immense forces during the uplift of the Rocky Mountains.