The cross section of the Syar quarry profile below says it all: dashed line existing grade, red line new excavation. A person is slightly taller than the dot of the "i" in "Property Line". The pit will drop steeply from the skyline trail 650 feet to the bottom of the pit. All of the land that you see in the photo below will disappear into the right edge of the pit.
Profile from skyline trail (true vertical height) - click to enlarge