In the Ghost Room we find an interesting object. Projecting from the ceiling is an 8-inch thick slab of angular brown rock. Its edges have been broken, rather than dissolved. This is a _clastic dike_. Evidence is lacking to definitely state its origin or manner of emplacement. But at some time in the past, there was an extensive crack in the marble which was filled by a mudlike material made up of bits of quartz, plagioclase, horneblende, epidote, clay, and other minor ingredients. It may have been washed in from the surface, or it could have been injected from below by earthquake shocks which cracked the marble and forced the pliable material into the cracks. Eventually it hardened into rock. Due to its non-soluble ingredients, the dike was not dissolved when the Ghost Room was formed. Like the “blades” we discussed previously, it remained as a projection into the room while the marble walls receded under solution activity. Being brittle, it has apparently been broken off periodically by the jar of earthquakes or cave collapse. Another obvious discrepancy in the marble framework of the caves is the thin layer of slate found in the 65-foot tunnel. This reveals an interruption in the limestone sedimentation of the Triassic sea. A thin layer of shale was deposited between limestone layers. Later, when the limestone became marble, the shale became slate. It should be mentioned here that limestone and shale vary greatly in their contents and often interblend with each other. “Pure” limestone is white. Different shades occur with different amounts of claylike impurities. When the impurities overshadow the limestone, then the rock may be called shale. The whitest marble in Oregon Caves came from the purest limestone. The darker, blue-banded marble is rich in slate impurities. [Illustration: The lacework effect of clay “worms”] LIFE IN THE CAVES If the Indians of southwest Oregon knew of Oregon Caves they left no evidence of the fact. Possibly its remote and rugged setting was too far away from their normal haunts near the fertile valleys and salmon-rich rivers. Or they may have known of the cave, but superstitions forbade their entering it. To our knowledge, Elijah Davidson was the first person to penetrate its depths. Other creatures used it regularly. Bears, mountain lions, coyotes, bobcats, skunks and other predators found the outer chambers ideal dens or resting places. Within the “twilight zone”—the galleries near the surface where some light penetrates—rodents of several kinds entered freely and even made nests. Today, we find the industrious woodrat still gathering mounds of sticks, leaves, flashbulbs, and hairpins to store near the 110-foot exit. Mice and rabbits are frequently seen in the cave. Occasionally the tracks of the ringtail betray his secretive hunting trips into the cave. In 1935, even a mountain beaver was found in the Ghost Room.