These eroded remnants of tuff are called tent rocks. There are many different kinds of tent rocks in the Jemez Mountains. Tent rocks form when some harder material or coating protects portions of the rock from erosion. There are many different ways that tent rocks can develop in tuff. Escaping vapor may heat the rock causing some particles to weld together more firmly, or the gasses might contain minerals that, when precipitated, form cement between the particles. The deposition of minerals by ground water may also form a resistant covering protecting the “tents” from erosion. The most obvious method occurs when a cap of harder stone slows the erosion of the soft rock beneath.