Note that the Orientation Slice is cut precisely to the (100) before the crystal is rotated and cut at either +.25 degrees and toward the flat, or â.25 degrees and away from the flat (as described in Figure 3).
The era was called the Dark Ages also because we don't have a lot of written sources from that time period, especially from the early part of the dark ages (500 to 800 CE).
The reason the Dark Ages got their name was because they were supposedly the sad, shitty years after the fall of the glorious Roman Empire. When the Roman Empire was taken out of the picture by barbarian hordes in A.D. 476, there was suddenly a shocking lack of nations that could swing the World Police hammer.