Box Tile

A baked clay tile shaped like a rectangular box, open at both ends; often used for flues and occasionally for voussoirs.

A baked clay tile shaped like a rectangular box, open at both ends, used for flues. [box flue tile] the abbreviation for “before present,” used especially in radiocarbon dating. The fixed reference date for before present has been established as ad 1950. Thus, 4250 bp would mean 4250 years prior to 1950, or 2300 bc. The year 1950 was the latest that the atmosphere was sufficiently uncontaminated to act as a standard for radiocarbon dating. The lower case “bp” represents uncalibrated radiocarbon years; the capitals bp denote a calibrated radiocarbon date, or a date derived from some other dating method, such as potassium-argon, that does not need calibration.