It occurs between Quinquagesima Sunday and Quadragesima Sunday, and readings on it are usually taken from the Book of Joel, Corinithians II, and the Gospel of Matthew.
It was not codified until the 1091 Synod of Beneventum by Pope Urban II, though, in the Lives of the Saints, Aelfric notes its practice as in the 990s. It occurs between Quinquagesima Sunday and Quadragesima Sunday, and readings on it are usually taken from the Book of Joel, Corinithians II, and the Gospel of Matthew. In the Catholic Church, the priest wears a violet cope and it's known as dies cinerum, while Eastern Orthodoxy replaces it with Clean Monday. For 10 points, name this day that marks the beginning of Lent with its namesake cinders and comes immediately after Shrove Tuesday.
It was not codified until the 1091 Synod of Beneventum by Pope Urban II, though, in the Lives of the Saints, Aelfric notes its practice as in the 990s.
Ash Wednesday