Van Hise Rock was named for the preeminent geologist of the 19th century, Charles Richard VanHise, who was also president of the University of Wisconsin-Madison from 1903-1918. VanHise used this rock to show the major structural features of metamorphic* Precambrian* rock and also to demonstrate the kinds of changes that occur in rocks through mountain building periods.
The requirement for seat height, however, is very simple: The top of the seat must be a minimum of 17 inches and a maximum of 19 inches above the shower floor.
1 It is difficult to find a pre-made shower cabinet this small. The usual minimum size is 32 x 32.  The minimum height of 80 (6'-8) over the fixture includes the required minimum clear floor space in front of the fixture, which must also have a minimum height of 80 (6'-8). See Guideline 4.