Soon they knew the Davidson story was true, more than true. Crawling from one chamber to another, they found a fairyland of weird grottoes and exquisite stone formations—pillars and spires, drapes, frozen waterfalls and grotesque forms—in shapes and sizes beyond their imaginations. Some they named from resemblance to familiar objects. At others they could only stare in awe and wonder _how can it be?_ Using the rope in steep places, they probed upward into another level of caverns where they were thrilled to find even more elaborate formations. At one place they wrote their names and the date, July 11, 1879. Here and there they saw evidence left by the few others who had entered the cave in the five years since it was discovered by their neighbor, Elijah Davidson. On and on they explored, returning to the entrance only when their last candle was growing short. Outside, stars lighted a midnight sky. Exhausted, happy, they vowed to return, then fell into bedrolls. Thus early visitors responded to the lure of Oregon Caves: to see the unseen and to know the unknown. Today, thousands of people enjoy the caves under less demanding circumstances. Yet the joy of personal discovery endures. For each visitor about to enter the cave, the thrill of learning something new and interesting about the earth beneath us is born anew. Throughout the world, caves loom large in the scope of history. Early man used them as dwelling and fortifications. Fugitives hid in them and thieves used them to cache their loot. Others have found them fine places to grow mushrooms. During the War of 1812 and the Civil War, Americans mined certain caves for saltpetre which was desperately needed to make gunpowder. Much of our knowledge of long extinct mammals has been gleaned from perfectly preserved remains, and even prehistoric drawings, uncovered by cave-probing scientists. To most of us, however, the greatest value of caves is the delight of seeing the strange beauties wrought by nature through countless centuries. And from this comes the challenge to understand the imperceptibly slow, relentless forces which produce them. This booklet sketches the processes which form, alter and eventually destroy caves. It is an attempt to share present knowledge with those who visit Oregon Caves National Monument.