: The Underworld of Oregon Caves National Monument by Contor Roger J - Oregon Caves National Monument (Or.)

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INTRODUCTION 1 HOW OREGON CAVES WERE FORMED 3 The Raw Material--Rock 3 Underground Erosion 7 Decoration 14 The Cave's Age 24 Other Cave Features 25 LIFE IN THE CAVES 27 Plant Life 29 THE FUTURE 30 HUMAN HISTORY 30 CONSERVATION AND PRESERVATION 31 GLOSSARY OF CAVE TERMS 34 SUGGESTED READINGS 36 RULES & REGULATIONS 37 ADMINISTRATION 37

INTRODUCTION

Three tired men unsaddled their horses where the mountain stream disappeared into the ground. They had fought their way 15 miles over wild, rugged mountains since leaving Williams Valley at dawn. Yet rest was far from their minds. Hurriedly they stuck tallow candles into lanterns made from tin cans, untied a lariat from a saddle, then walked down the valley. They stopped where the stream, now larger, reappeared from a shadowy crevice under a cliff.

"This must be it," said one of them eagerly, "just like Davidson said." And with mixed feelings of excitement, fear, and the overwhelming grip of adventure, they followed flickering candlelight into the dark opening. Tales of persons lost for days in other caves were fresh in their minds, so they uncoiled a ball of string as they went. Later they could follow it back out.

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.

HOW OREGON CAVES WERE FORMED

If we could turn back some 180 million years into geologic time, we would find the North American continent a much different place. This was the Triassic Period. Early dinosaurs thrived in primitive forests over much of the United States. The area around southwestern Oregon was not yet part of the continent; it was a shallow arm of the sea. Smoldering volcanoes jutted out as cone-shaped islands or poured forth fumes and lava from the distant mainland.

During quieter centuries the age-old process of life and death went on within the sea waters. Fish, clams, coral--even tiny one-celled creatures too small to be seen--extracted a mineral called calcium carbonate from the water. With it they built bones, shells and skeletons. When these animals died, their hard parts settled to the ocean bottom. Gradually, layers of calcium carbonate were built up.

At the same time certain chemical functions of ocean plants extracted carbon dioxide from the water and caused still more calcium carbonate to precipitate and add to the sediments. The layers deepened. Eventually the weight of overlying sediments and the ocean above compressed them into a rock called limestone.

In different parts of the sea, and under varied conditions, other ocean sediments were deposited. Near the shore, wave-swept sand accumulated and eventually became sandstone. Fine silt and clay carried to the sea by rivers settled in bluish layers which were to become shale. Near rocky headlands, course gravel deposits became cemented into a hard mass called conglomerate.

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