Boxwork is an uncommon type of mineral structure, which is formed by erosion rather than accretion and is found in caves with erosive environments. Boxwork is formed when bedrock between preexisting calcite veins were preferentially weathered away as the cave developed. Boxwork is commonly composed of thin blades of the mineral calcite that project from cave walls or ceilings and that intersect one another at various angles, forming box-like or honeycomb patterns. The boxwork fins once filled cracks in the rock before the host cave formed. As the walls of the cave began to dissolve away, the more resistant vein and crack fillings did not, leaving the calcite fins projecting from the cave surfaces. Some of the most extensive boxwork deposits in the world are found in Wind Cave.
Today in Saint Louis, would not be a very good day to go into a cave. That is because, today is a very rainy day and caves have this habit of filling up with water when it rains. Since, it is a rainy day that also makes it a rest day, no bicycling today. I knew that this rain would be coming. I just hope that it will shut off before too many days. I don’t really need a week of rest.