Organic agency in calcrete development

Calcrete, a widespread surface material type of considerable geomorphological significance in the world's drylands, has in recent years been seen increasingly as a product of various biogenic processes as much as of physicochemical processes. This paper reviews the literature on this topic that has developed over the past two decades and draws attention to the role of organisms as sources of carbonate material, catalysts of carbonate precipitation and creators of a whole series of fabrics and structures, both constructive and destructive. (C) 1996 Academic Press Limited