The limestone used for the retaining walls of the Shepherd’s Garden is Nebraska Limestone quarried at Weeping Water, Nebraska.

Weeping Water limestone (in Andrew shale), is exposed in valley sides of Weeping Water Creek and along west side of North Branch Valley about 1 mile northwest of Nehawka [Cass County, Nebraska]. The thickness of the vein is 6 feet. Is light-colored, massive, breaks down in large blocks, and shows tendency to weather into rough, nodular forms. It is overlain and underlain by shale.

The rock was deposited in shallow water in the northwestern part of a shallow seas 305 million years ago during the Pennsylvanian Period. The rock in the mine was deposited during periods of rising and falling sea level controlled by glaciation at the South Pole.