STEEP SLOPE STONE LINES (STEEPS):
STEEPS ARE STONE LINES ON GRADES IN EXCESS OF 50%.
According to "Perceiving 'Walk-on-able' Slopes by J.M. Kinsella-Shaw, et al" the participants would "...walk up the ramp comfortably, at an ordinary pace, while maintaining upright posture and making full "flat-footed" contact..."
Depending on the participant the maximum slopes traversed were 22% to 32%.
Using only manual labor to lift, stack and manipulate stones weighing hundreds to thousands of pounds on a flat surface would be difficult at best. On a 30% plus slope it is impossible.
A WALL UNSEEN describes accessing a stone line on a steep slope.
The examples below are extreme slopes of 50% to 80% where modern equipment such as tractors cannot close to traversing.
The Shasta Steep Slope Map shows the locations of over 85 stone lines with line segments on slopes of 50% to 80%.
The areas adjacent to the stone lines are undisturbed and NO SIGNS OF CONSTRUCTION.