Ledges are often left along the edges of sinuous lava tube passages, and are usually somewhat rectangular in cross-section, joining walls and floor. Curbs, benches, and shelves are other names commonly applied to these features, which mark the edges of late-stage flows. Ledges may also occur higher on walls and be undercut, leaving catwalk-like suspended ledges. These features are more common near entrances since cooling is more rapid in those areas.
AUTHOR: Dave Bunnell