From the Introduction:
Even in some places where one might not suspect such a thing much sought after fine stone lies close under the surface. This quarry is one such place where the thin cover of soil and grass has been torn open to get at the stone beneath. Stone that is quarried here in big blocks and as gravel for the construction of monumental structures nearby and far away.
It helps that the hilly terrain makes it easy to get at the stone. After removing only a little earth the quarrymen were able to get quarry the precious good on no less than three levels with little effort. Although ramps connect these levels the heavy blocks of stone can be hauled away on each one of them. Even the tree trunks used to move the heavy stones can be cut in the immediate neighborhood of this quarry.