Analyzing Stonework
This is why they have been partially unable to figure out how unstable the ruins of the cathedral actually are. What has helped is realizing that analyzing the color of the stonework could provide useful information. They shared that by observing the varying shades of the limestone blocks, the researchers could determine which temperature the blocks have been exposed to.
Analyzing Stonework
Determining The Strength
When exposed to temperatures between 570°F and 750°F, the iron contained in the limestone decomposes, leaving behind a red residue. Higher temperatures causes the color to turn to black. Once 1500°F is reached, the blocks are reduced to powdery ash. This is how the researchers were able to determine the strength of each individual stone.
Determining The Strength