Chalk produce, and thus widely used in the developing world, calcium-based chalk can be made where the crumbling particles are larger and thus produce less dust, and is marketed as "dustless chalk". Colored chalks, pastel chalks, and sidewalk chalk (shaped into larger sticks and often colored), used to draw on sidewalks, streets, and driveways, are primarily made of gypsum. Chalk is a source of quicklime by thermal decomposition, or slaked lime following quenching of quicklime with water. In southeast England, deneholes are a notable example of ancient chalk pits. Such bell pits may also mark the sites of ancient flint mines,
Sidewalk chalk to use anamorphic drawing when drawing with sidewalk chalk. Nonanamorphic drawing are drawings that are drawn to be observed face-on, whereas anamorphic drawings are drawn to be observed from a different viewpoint. Julian Beever, in a Q&A with Adam Boretz, explained his drawing of his first anamorphic sidewalk chalk drawing, Swimming Pool: Sidewalk Sam was well known in the Boston area for his reproductions of European masterpieces, chalked or painted on the sidewalk. Sidewalk chalk Sidewalk chalk is typically large colored (and sometimes white or cream) sticks of chalk (calcium sulfate rather than rock chalk, calcium carbonate) mostly used for