Medieval Stone: Quarry to Castle

On tour at the Ozark Medieval Fortress many guests have asked about the quarry and if it is big enough to provide all the rocks for the castle and how the stone is quarried and carried to the castle site.

A first look at the wall of limestone at the quarry shows how beautiful the Arkansas grey-white stone looks.  This is because the limestone has magnesium and is actually called dolostone.  It  is a hard limestone that is perfect for the castle.  It does mean a  lot of extra work for the blacksmith to keep the chisels sharp and make the metal wedges for the quarrymen.  A first look also makes the quarry seem small because the castle project is so big.  It takes a lot of stone to build a castle, but using techniques from 1226, the rocks are not needed all at once and there is no worry about running out of rocks in the Ozarks. 

The committee of French Medieval historians who are the authenticators for the castle authorized in the beginning (in 2009) the use modern drills and explosives under United States specifications to open the quarry.  That can be seen in the drill holes which are large and far apart.  In the Medieval to drill the holes, the quarrymen used a metal star bit, like a long chisel drill, which was struck with a mallet, turned, then struck again.  This bit was as thick as a man’s thumb - not 2-½” across like a modern drill.  Also, in the Middle Ages the drill holes would be one “hand” (4”) apart.  The holes could be either filled with water to freeze over the winter, or filled with packed dry wood then watered for expansion, or split away with wedges pounded into the fissures.  The historians’ authorization saved a year’s work just on preparations in the quarry.

The large blocks of stone that were initially loosened from the cliff side were broken into slabs approximately one “span” (6-8”) thick.  This was done by following the sedimentary lines of natural weakness in the stone.  First, wedges were driven into the cracks and then metal rods were used to complete the break.  Those slabs were then turned into usable and moveable stone for the castle wall.  The largest were used for the first lintel stones over doors as well as the anchor stones in the wall.  Large stones continue to be used as the anchor stones as well as the rough stones for the stone carvers to turn  into specialty pieces around the doors and arrow loops.  The slabs are also split into face stones for the castle using a French tool called a “chase masse”, a Medieval French stone cutting tool which looks like a hammer but is not.  One side is placed against the rock and the other side is then struck with a hammer.  This causes a series of shock waves to go through the rock and split it.

The rocks that are man-sized, which means the size one man can lift,  are loaded into a large wheeled horse cart for transport to the castle.  Larger stones are rolled onto a wooden sled and then dragged where needed by the horse and carter.  All this takes teamwork between the quarrymen, masons, stone carvers, carter and, of course, the horse. 

Once the stone is at the wall, the workers at the Ozark Medieval Fortress, like those of the Middle Ages, have the choice of using the Roman tread wheel crane to lift the stone or the use of ramps.  Even though the crane is amazing and will be necessary in the future as the walls get taller, ramps are preferred by the men because if a rope breaks the consequences are much less if the big stone is on a ramp.  The ramps are also much easier to move to where they are needed.  The large stones are a lot of work to move and downright scary to fingers and toes, but make the castle stronger and are worth the extra effort and danger. 

Once on the wall the various sized stones are arranged by the masons for the proper alignment.  It looks like a jigsaw puzzle.  Their skills are impressive.  They have to be aware of the shape, strength and interlocking connections of each stone.  They use some as face stones that show to the outside, some as anchor stones that show but also reach into the wall to tie it together, and some as fill and leveling stones.  When they have it all set up, they still have to come back and mortar it together.  They must be sure the wall is not only level on top, but plumb on both the inside and the outside.  That means that each stone had to first be split from the quarry cliff wall, then split into a slab, then broken into a usable stone, then lifted into the wagon or sled, then hauled and lifted out, then lifted or dragged up to the top of the wall and finally available for the mason to move into place, arrange or rearrange and then