The eruptions from the Four Craters Lava Field were accompanied by a slight sinking of the older rock surface, forming a shallow, graben-like structure about wide and extending to the south into an old lake basin. Crack in the Ground marks the western edge of this small, volcano-tectonic depression. The crack is the result of a tension fracture along a hingeline produced by the draping of Green Mountain lava flows over the edge of upthrown side of the concealed fault zone. The fissure is located at the southwest corner of Four Craters Lava Field. Hikers can walk the length of the main crack and explore its tributaries.