- GeoRef, Copyright 2004, American Geological Institute. Reference includes data from Bibliography and Index of Geology Exclusive of North America, Geological Society of America, Boulder, CO, United States
At Maddocks Hill in Shropshire, central England, a basic sill of late Ordovician (?) age intrudes the Cambrian shales. Near the contact, the shale has been recrystallized to a hard hornfels, and thin sections indicate it as a thermal effect only. Comparison is made with the Whin and Palisades sills.