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,
Chalk talk (1842-1905). Today chalk talks are still regularly used as a method of preaching scripture visually, by evangelists that have artistic ability. A book by Jeanne Bridge, "Chalk Talk for Catechists," gives us a useful introduction to a catechetical method, where we see (what?) is an increasing interest among all sectors of people. Basically, it talks about "speaking the message" by illustrating with simple chalk drawings, along with the talk, that highlight the main points of the lesson. The word which is predominant is at a lead together with the word [this phrase says nothing], so that the word and the