Obelisks were usually carved out of reddish-coloured granite foundat Aswan. Sometimes dark grey basalt was used.
The dimensions varied: the tallest known obelisk remains unfinishedin a cave at Aswan (about 40m) and the smallest is less than 2metres in height. On many obelisks there are inscriptions inhieroglyphics saying to which gods they were dedicated and to thePharaoh who ordered their erection.
The huge unfinished obelisk at a cave at Aswan helps to show us howsuch monuments were made. First of all the Egyptians insisted thatthe stone to be used should have no defects, cracks or blemishes.Next the rock was cleaned and the surface of the rock was scrapeduntil it was smooth and flat. After smoothing, the contours of theobelisk were marked out on the ground and a deep ditch was bashedout of the rock out around them by gangs of slaves hammering awaywith pounding balls made from dolerite. These were especially hardstones made from dolerite, dark coloured basalt from the desertvalleys of Egypt. These stones weighed anything up to 5 kilogramseach.
The fourth face of the obelisk was torn from the seam of rock withenormous wooden wedges which were driven into previously preparedholes at regular intervals. The wedges were soaked with water, andas they expanded the rock split.
At this stage hundreds maybe thousands of slaves, depending on thesize of the obelisk, worked with ropes and jacks to raise theobelisk from the ditch and to heave it on to planks resting upon amassive sledge. It was a scene of organised chaos as hordes ofslaves, swarmed about the great stone. Although there was nothrobbing machinery there was noise: of stone grinding on stone,the creaking of straining timber, the shouts of the foremen, thechanting of slaves.Once it rested safely on its sledge, the obelisk was dragged tothe bank of the Nile. Here it was received by more gangs of slaveswho then loaded it onto a long barge to be taken to itsdestination.On arrival, the obelisk had to be hauled on its sledge from theriver to its final resting place. Again hundreds or even thousandsof labourers, depending on its size were pressed into service.
The next task was to pull the obelisk upright. As some monumentsweighed up to 500 tonnes, this was obviously quite a problem andnobody today knows exactly how it was done. One possible method wasthat the base of the obelisk was placed on the edge of the pedestalon which it was going to stand. The obelisk was made so that oneside of the base could be fitted into a slot cut in the pedestal.This prevented the obelisk from slipping while it was actuallygoing up.While the obelisk was raised by ropes and jacks, a heap ofmaterial (usually bricks) was pushed underneath it to support itand keep it steady.Finally the heap of bricks grew high enough to allow the obeliskto stand upright on its pedestal. Then the slaves were set to workremoving the material.