Paving blocks were the primary use of Missouri traprock in the late 1800s to early 20th century. Much of the material was shipped from the quarries by railroad to cities such as St. Louis and Chicago. Much of the paving block consisted of “motion” quarries. This type of quarrying utilized surface material and typically was done by one or two men.

Paving Blocks

The natural jointing in the rock, called a rift or run by the quarryman was taken advantage of along with the grain or preferred bedding plane of the rock. This mostly horizontal plane should no be confused with the bedding planes in sedimentary rocks as traprock is specifically igneous in origin. The quarryman would first drill a series of holes in the direction perpendicular to the prominent jointing. The rock was subsequently split by tension using a wedge and feathers in each drill hole.

The common paving block size was 11 to 14 inches long, four inches deep and seven inches wide. Other sizes were manufactured. The quarry operators were paid by the brick and often had to pay a royalty to the landowner.

Granite became the preferred material for paving stones in Missouri due the hardness of the traprock creating a wear surface that became polished and slippery from wear. The “motions” and paving block industry as a whole declined signficantly by the end of the 19th century and most of Missouri’s traprock quarries were abandoned until the 1920s.