Townlands are the smallest administrative division and on average covers about 350 acres. It is the most ancient geographical unit in Ireland and the one in which researchers struggle to identify when searching for their ancestors. Many townlands share the same name. The townland was named at an early period and often the name was derived from some local physical feature or landmark such as a mountain, bog, forest, a village, or a church. The townland became standardized as the unit of measurement during the seventeenth century surveys. The townland names were originally in Irish Gaelic, but they became modified as a result of English speaking clerks writing the names as they heard them, using the Latin alphabet to approximate Gaelic word sounds.