Cave of the Mounds the Interior and the National Park Service. To be considered a NNL, "a site must be one of the best examples of a natural region's characteristic biotic or geologic features." Cave of the Mounds is home to many varieties of speleothems. As with most caves, stalactites and stalagmites are common. Formations found inside the cave include: These formations come in many different brilliant colors such as reds, browns, blues, and grays. The reds and browns are caused by the presence of iron oxide in the formation. Similarly, blues and grays are caused by manganese oxide. Some speleothems are even partially
Cave of the Winds (Colorado) Cave Coral, or Cave Flowers; also commonly considered to be Beaded Helectites which appear to defy the laws of gravity by growing in strange directions and not being forced down by gravity like many cave formations. Silent Splendor is sealed from public view by an Environmental Gate, a large tube made of PVC that seals in moisture to allow the area of the cave to continue forming. Other lesser known attractions include a "bottomless pit," often the scene of practical jokes by the guides, and a one of a kind region referred to as "the rat." In the late 1980s