Explore the geology of the Brandywine Valley and its impact on the milling industry on a tour created and led by Hagley Guide Tom Stack. Visitors will work with fellow guests to cut a piece of Delaware Blue Rock and take a souvenir home. Tour involves walking on uneven ground. Please dress appropriately. Walking tour is included in cost of admission. Use Hagley’s main entrance off Route 141 in Wilmington, Delaware. The tour runs 11 a.m. to 12:30 p.m. on Saturdays September 21, October 19, and November 9.