Visitors explore the geology of the Brandywine Valley and its impact on the milling industry. Take home a piece of Delaware Blue Rock as a souvenir. Tour involves walking on uneven ground. Included in admission and free for members. Reservations requested, call (302) 658-2400, ext. 261. Use Hagley’s main entrance off Route 141 in Wilmington, Delaware. This is a Let’s Move! event.