Ghost Room
The Ghost Room—the largest room on the tour— has two parts: the Ghost Room Platform and the Ghost Room Floor. The Ghost Room Platfo
rm is set above the actual room, just after the tunnel connecting to Miller’s Chapel. The Ghost Room Floor is the deepest part of the tour at 220 feet underground. From these vantages, the room’s features are visible: the Spitting Stone, vermiculations, speleothems, the underground River Styx, and an igneous intrusion with associated faults and water flow control. Due to these intersecting elements, the Ghost Room is a particularly grand showcase of geology.
Geology
Room Development
There is a large igneous intrusion cutting the Ghost Room ceiling in half. An intrusion is simply what it sounds like—one rock intrudes, or slices through, another rock (Bates and Jackson 343). During the tectonic activity that shaped the Klamath-Siskiyou region, a large crack formed as rising molten rock pushed overlying rock aside. Later, magma squeezed through the crack and wedge apart the marble. The magma cooled into a rock called diorite (Glancy 3). Diorite is much more resistant to erosion than marble, which is the reason the intrusion sticks out farther than the ceiling (Murck 125).
The room is split in half again by a fault that also slices through the igneous intrusion, which shows a foot or so of offset as seen in the picture below. Faults, as well as joints, cracks, and other weaknesses, undermine the strength of the marble. They also facilitate more movement of water, allowing larger rooms to develop (Murck 121; Palmer 78). Also, the Ghost Room is so large because of waterproof rock layers and faults that, that funnel water into the room (Palmer 232; Roth 40).
Cave Formations
The Spitting Stone, or the never-ending-drip, is located on the left side of the platform heading towards the stairs.Dripping water formed the small knobby stalagmites but, as shown by the numerous pits and craters, water has started to erode these formations (Roth 36).
Rillenkarren are seen on the ceiling facing back towards Miller’s Chapel, close to the stone railing. They are likely formed by acid dew, caused by either two large masses of humid air mixing, warm floodwaters, or both. The resulting carbonic acid runs down the ceiling in tiny streams of water, carving small grooves (Lundberg 315; Gines 470; Roth 35-36).
Vermiculations occur on the overhanging rocks above the Ghost Room Platform. Their presence indicates that the room was once filled with water and sediment that slowly dried out. These particular vermiculations are not as well developed as those seen in other rooms.
On the ceiling above the stream grotto, white drapery and needle-like stalactites can be seen. The whiteness of the formations demonstrates the increasing purity of calcite at depth as well as an increase in fulvic acids relative to humic acids (Roth 41).
Water Flow
The igneous intrusion is not only more resistant to erosive processes, but it is resistant to water flow as well. Unlike marble, the intrusion is mostly impermeable, meaning water cannot pass through it (Palmer 235-236). Formation growth makes this water flow pattern clear. 
From the right side of the Ghost Room, water percolates down, depositing calcite as the needle-like stalactites and drapery. But when the water reaches the intrusion it is redirected downwards—almost no formations are seen to the left of the intrusion. Immediately to the right of the intrusion, there is a concentration of drapery and flowstone.
Below the intrusion, an underground stream, which is part of the River Styx seen in Watson’s Grotto, serves as a drainage outlet for the room. In 1996, bones from two ice-age jaguars were uncovered upstream. Using carbon dating, a form of radiometric dating, they were found to be 38,600 years old. They are also the most complete jaguar skeletons discovered this far north (Roth 39).
References
Bates, Robert and Julia Jackson, ed. Glossary of Geology. Alexandria: American Geological Institute, 1987. 343.
Bini, Alfredo, Cavalli Gori and Silvio Gori. “A Critical Review of Hypotheses on the Origin of Vermiculations”. International Journal of Speleology, v.10: 1, 1978.
Gines, Angel. “Karren.” Encyclopedia of Caves and Karst Science. John Gunn, ed. New York: Fitzroy Dearborn, 2004. 470-473.
Glancy, Sarah. Dike Project, Oregon Caves National Monument. Cave Junction: Oregon Caves National Monument, 2009. 1-13.
Lundberg, Joyce. “Karren.” Encyclopedia of Caves. David Culver and William White, ed. Burlington: Elsevier Academic Press, 2005. 315-321.
Murck, Barbara. Geology: A Self-Teaching Guide. New York: John Wiley & Sons, 2001. 121, 275-276.
Palmer, Arthur. Cave Geology. Dayton: Cave Books, 2007. 78, 232, 235-236.
Roth, John. “Interpretive Manual for the Monument’s Showcave”. Cave Junction: Oregon Caves National Monument, 2011. 32-33, 35-36, 39, 40.
Veni, George. “Passages.” Encyclopedia of Caves. David Culver and William White, ed. Burlington: Elsevier Academic Press, 2005. 436-440.