Ten miles south of Great Barrington along US 7 and MA 7A toward Ashley Falls brings you to Bartholomew's Cobble, a 'cobble' being a high, rocky knoll of limestone, marble or quartzite. The highly alkaline soil of this 329-acre reservation supports an unusual variety of trees, flowers, moss and especially ferns. Five miles of hiking trails provide routes for enjoying the cobble and the woods, which are set beneath a flyway used by over 200 species of birds. Try the Ledges Trail that weaves along the Housatonic River.