At the end of the last ice age, when mammoths and mastodons roamed thick pine forests blanketing the East Coast, some of the first human residents of the Americas made a discovery in what is now Reisterstown: a rare, translucent stone.

Members of the nomadic Clovis people dug into what is now part of the grounds of St. John’s Episcopal Church, Western Run, unearthing chalcedony, a type of quartz. They chipped away at the stones, forming them into arrowheads or spear tips. Then the Clovis people disappeared.