The harder stones, such as granite, granodiorite, syenite, and basalt, cannot be cut with copper tools alone; instead, they were worked with time-consuming methods like pounding with dolerite, drilling, and sawing with the aid of an abrasive, such as quartz sand.[11][12] Blocks were transported by sledge likely lubricated by water.[13][14] Leveling the foundation may have been accomplished by use of water-filled trenches as suggested by Mark Lehner and I.E.S. Edwards or through the use of a crude square level and experienced surveyors.[15][16]