Fire extinguishers were placed in alcoves along the tunnel walls. Geological features in these canyons include spires, windows, giant alcoves and desert varnish. Caves and other alcoves that offer protection are used as litter dens. These figures sit above small fountains inside the alcoves. The cloister is long and contains 42 interior alcoves. Others had no such side alcoves; these are known as "undifferentiated tombs". The cathedral also contains two Ogham stones, which rest in small alcoves. There are some optional ladders to allow access to the cavates (small human-carved alcoves). The short side tunnel alcoves were excavated using explosives. The northern alcoves both contain eight elevators while the southern alcoves both contain four elevators. There are also several cathedral-like alcoves that branch from the main tunnel. The remaining tiling in the alcoves is white. One cataract (Unnamed Coulee) is high and had three alcoves over more than a . Species showing these traits are on display in alcoves on either side of the path. It is in these alcoves that most of the scientific experiments were conducted.