The marks seen on the unfinished obelisk are not scoops. The ancient Egyptians were not softening the bedrock and scooping material out. Instead, they were softening the bedrock using heat from magnetic induction to make the rock surface brittle and grinding it down. Their techniques for grinding very hard stones such as granite and the salt would be more familiar to us when it comes to techniques for working wood or marble. Therefore, power tools such as planar, rotary grinder, drills, circular saws, lathe, etc. is what you should envision. They grinded away the material using something that was spinning or rotating very fast. They did not scoop rocks like ice cream, or in one motion moved a tool across the rock surface like a cheese grater to remove material. They were able to maneuver the studded rotary wheel grinder beneath and around the side of the unfinished obelisk, from all sides, leaving behind only a narrow rock spine.