The field trip spent much of the time in and around a 20 km diameter volcanic caldera. What seems surprising is that it is 1.4 billion years old and yet retains some of the original topography. It was probablhy buried by younger sedimentary rocks but later eroded and the resistant volcanic rocks show the shape of the caldera. There is just about no tilting or folding in all that time. The igneous activity was the source of an iron deposit in sedimentary rocks that was guarded by a Union civil war fort. There was a battle and the Union abandoned the fort, with the conferates having over 1000 casualities.
Chris