The processes that creates gneiss can recreate normal granite if carried on long enough, and gneiss can also form from gabbro or shale. Schist and quartzite may be formed alongside gneiss, along with other types of metamorphic rock formed from igneous rocks. Gneiss is very common and actually forms the majority of the Earth's lower crust, so any deep tunneling encounters gneiss.
Inventoried roadless area. Inventoried Roadless Areas are a group of United States Forest Service lands that have been identified by government reviews as lands without existing roads that could be suitable for roadless area conservation as wilderness or other non-standard protections.
A close-up of a gravel road in Terre Haute, Indiana. A gravel road is a type of unpaved road surfaced with gravel that has been brought to the site from a quarry or stream bed. They are common in less-developed nations, and also in the rural areas of developed nations such as Canada and the United States.