On the 4th Saturday of the month, you can go on a guided Geology Walking Tour and learn about the geological history of the volcanic formations & rocks at Boyce Thompson Arboretum. The tour starts at 1:30 pm. Admission is $9 for adults & $4.50 for ages 5-12. The cost of admission includes the Geology Walking Tour. Boyce Thompson Arboretum is located west of Superior on Highway 60 at Milepost #223 & about one hour due east of Phoenix on the Superstition Freeway.