Introducing bombturbation, a singular type of soil disturbance and mixing

This article introduces the term bombturbation for cratering of the soil surface and mixing of the soil by explosive munitions, usually during warfare or related activities. Depending on exactly where the explosion occurs (above, on, or below the soil surface), bombturbation excavates a volume of soil from the site of impact, forming a crater and spreading much of the ejecta out as a surrounding rim of mixed, but sometimes slightly sorted, debris. Because such explosions are nonselective, that is, all of the material removed is mixed and redistributed, bombturbation is often a proisotropic form of pedoturbation-causing existing soil horizons to be entirely destroyed or intimately mixed. Although anthropogenically linked, bombturbation fits most appropriately under the existing pedoturbation category of impacturbation. Unlike the rare instances of extraterrestrial (meteoroid) impacts, impacturbation by bombs and munitions is common worldwide; on some battlefields, it is so prominent that little or none of the original soil surface remains undisturbed. Indeed, many soils and landscapes that have undergone bombturbation are so pedogenically and topographically altered, largely because of the long-lasting craters left behind, that the soils within the craters may have shifted onto a new pedogenic pathway-something that many other forms of pedoturbation often cannot accomplish. We use examples, mainly from the World War I battle of Verdun (France), to illustrate crater and rim morphology and postbombturbation soil development and to highlight the importance of this newly defined pedoturbation process.