Experiments were performed to determine the type of landforms that develop, when varying thicknesses of granular material are fluidized by emission of gas from vents of differing size and pattern. Two types of craters formed above single vents, explosion craters with steep sides and little or no floor, and fluidization craters with low rims and flat floors. Crater chains form above multiple vents.
Coalescence of craters above a series of vents or emission of gas along a linear or sinuous vent produces a fluidization trough. Within the trough fluidized granular material migrates from areas of thick to thin material, as well as downslope. The result is a channel with a well-defined head that decreases in depth away from the head. A comparison of the experimental results with selected lunar topographic features permits the tentative conclusion that some lunar craters, crater chains, crater clusters, and rilles are of endogenic origin. These features probably formed by fluidization of the lunar regolith during emission of gas along fractures.