Since prehistoric times, the process of cutting rock to make millstones has been one of the most important industries in the world. Different civilizations and cultures have produced their own styles of grinding stones, which have been used in mills to process wheat, corn, and other grains into the flour and meal that was necessary to feed a growing population. The earliest rotary millstones, known as querns, were turned by human power. Later in history, larger millstones were manufactured that required animal, water, or wind power to turn them. These larger millstones required less human effort and ground greater quantities of grain, but also required regular maintenance and replacement. As a result, millstone quarries increased greatly in number and size in the late 19th and early 20th centuries, with the largest quarry sites extending as far as nearly a half-mile square to about 12 square miles.The first part of this book compiles information on the millstone industry in the United...