Part 1

Produced by Stephen Hutcheson and the Online Distributed Proofreading Team at http://www.pgdp.net

The Underworld of Oregon Caves National Monument

_by_ ROGER J. CONTOR

Published by Crater Lake Natural History Association

Produced in cooperation with the National Park Service

Copyright 1963 by Crater Lake Natural History Association Printed in U.S.A.

© _CRAFT PRINTERS, INC 1205 Klamath Avenue Klamath Falls, Oregon 97601_

About the Author

Roger J. Contor attended the University of Idaho and Montana State College, concentrating in the fields of zoology, botany, forestry, and big game management. His association with the National Park Service began as a seasonal employee in 1949 in Yellowstone where he served intermittently in various capacities into 1955. Later that year, he joined the permanent staff of the National Park Service as a park ranger, serving in Yellowstone, Rocky Mountain, and Bryce Canyon National Parks.

In 1960, Mr. Contor became management assistant for Oregon Caves National Monument, where he remained until early 1962. He then returned to Rocky Mountain National Park, also as a management assistant. He is a member of The Wildlife Society and Phi Beta Kappa and has authored wildlife articles for _National Parks Magazine_, _Field and Stream_, _Outdoor Life_, _Wyoming Wildlife_ and _Denver Post_.

_ENTRANCE_ _TREE ROOT_ _RIVER STYX BRIDGE_ _WHALE_ _DRY ROOM_ _WIGWAM_ _110 ft. EXIT_ _BANANA ROOM_ _NIAGARA_ _KINGS PALACE_ _GRAND COLUMN_ _CHAPEL_ _RIMSTONE_ _PARADISE LOST_ _GHOST ROOM_ _EXIT TUNNEL_

CONTENTS

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.

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.

Before going on, let us define the word _cave_ as we consider it here. True caves are formed in soluble rock—limestone, marble, gypsum or dolomite. They usually contain some redeposited mineral in the form of stalactites, etc. As most caves occur in limestone, the term _limestone cave_ is often used to describe any true cave, even though it may actually occur in dolomite or marble. The cave-forming process will be basically the same for either type of soluble rock. We exclude from this definition mines, lava tubes, ice caves, and sandstone depressions such as those used by cliff-dwellers in the Southwest. While they are “holes in the ground,” they are formed in different ways than are the limestone type caves, and therefore are not usually referred to in geological discussions of caves.

HOW OREGON CAVES WERE FORMED

_The Raw Material—Rock_

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.

This steady formation of sedimentary layers was periodically interrupted by volcanic activity. Heavy clouds of volcanic ash and fragments settled into the sea. Molten lava poured into shallow bays or welled up from subsurface volcanoes to mix with calcium carbonate muds. When volcanism subsided, the seas went back to the quiet deposition of limestone. Today at Oregon Caves we find evidence of this interbedding of sedimentary and volcanic materials. An example of such interbedding can be seen above the parking area near the Chateau.

Thus mixed deposits of volcanic and ocean sediments continued to collect for several million years. Apparently this steady transfer of material from one part of the earth’s crust to another created a crustal imbalance. The edge of the continent was under a strain. Then, like an accordion, a tremendous folding of the lands along the Pacific Coast occurred.

The floor of the sea was lifted above the ocean’s surface to form a new coast line in this vicinity. Violent stresses in the earth’s crust created intense heat and pressure which changed, or metamorphosed, the rocks. Shales were altered to slate. Sandstone became quartzite. Limestone became the marble so important to Oregon Caves. Even the volcanic materials were altered considerably from their original form. The resultant geological belt composed of inter-bedded layers of slate, quartzite, marble, and metamorphosed volcanics is known as the Applegate Group.

After the uplift, there was a long period of crustal stability. The folded mountains were eroded away and the area became a flattened plain near sea level. As a result, its streams were sluggish and meandered slowly to the ocean. Then, in various stages, the plain was uplifted in another period of crustal adjustments which produced a flat-topped plateau, so to speak, known as the ancient Klamath Peneplane. This restored the vigor of the stream erosion, which helped at times by glacier sculpture, dissected the plateau into the mountains we know today. The Siskiyou Range surrounding Oregon Caves National Monument is part of the Klamath Mountain System.

Let us focus on one of the ancient marble layers of the Applegate Group, for this is the rock strata in which Oregon Caves were formed. It is actually a narrow, tilted belt, varying in thickness up to 400 feet. It dips eastward into the earth at an angle of about 60° and can be followed in a southwest-northeast direction for about 4 miles along the west shoulder of Mt. Elijah (see illustrations on page 4). Examination of the marble layers inside the exit tunnel or the outcrop at the beginning of Cliff Nature Trail reveals many fractures caused by the stresses of upheaval. Some are vertical cracks, but there are also many cross fractures at varying angles.

When tested for chemical composition, Oregon Caves marble samples have averaged 93 percent pure calcium carbonate (CaCO₃). Its bluish color is derived from the remaining percentage of impurities. Without these, it would be white. A good example of nearly pure calcium carbonate is the white chalk used on blackboards.

Without this belt of soluble marble, and without the fractures within it, natural processes could not have produced the “Marble Halls of Oregon.” It is the foundation, the framework, and the raw material of the caves.

_Underground Erosion_

The first requirement in the genesis of Oregon Caves—the right kind of rock—was met. Next came the erosive agent which was to carve it into caverns. This was the flow of underground water.

The present rainfall in this area averages 50 inches a year. During the many thousands of years the caves were forming, the climate may have varied from wetter to drier many times, but it is safe to assume this has always been an area of relatively heavy precipitation. The steep, mountainous terrain and deep-cut valleys of southwestern Oregon are characteristic of aggressive stream erosion that goes hand-in-hand with a healthy supply of rainfall.

Some of the rain evaporates and returns to the air. Some of it soon runs into streams and is carried rapidly to the ocean. The rest of it seeps into the ground where it is delayed for a time in its inevitable return to the sea. Under the force of gravity, it trickles downward rather steeply through joints and cracks in the rocks, or seeps between particles of sand, gravel, or clay. Below the ground surface it joins a zone of saturation, or _phreatic zone_.

RAIN FALL } _Vadose zone: water moves from surface to water table (vertically)_ —_Water table_ } _Phreatic zone: total saturation, water moves slowly and nearly (horizontally)_

Here cracks, pores, and all spaces within the rock are completely filled with water. There are no airspaces. Water movement within the phreatic zone is comparatively slow, varying from a few inches a year to a few feet a day, depending upon the permeability of the rock structure. And the movement is usually horizontal, following the contours of the land in the same direction as surface streams. Eventually this water will find its way back to the surface at a lower elevation where it usually emerges as a spring. It is phreatic water which feeds the mountain streams and rivers many weeks or months after the last rainfall. It might also be pumped from a well for human use. A large portion of the earth’s population depends upon well water from these great underground reservoirs.

How deep does phreatic water exist? This depends upon the porosity of the rock, or its ability to contain water. Most mines that penetrate many hundreds of feet encounter little water at great depths. Pressure of the overlying rocks is so great that open spaces capable of holding water cannot exist. So the earth’s crust contains available well water only in restricted zones not far from the surface. The top of the zone of saturation is called the _water table_. It is here that the most rapid flow of phreatic water occurs, for the joints and interspaces are wider nearest the surface. Between the water table and the surface is the _vadose zone_, in which the spaces are partly filled with water and partly filled with air. (See illustrations on page 7). Vadose water content varies greatly with weather conditions. As rainfall is scant in southwest Oregon during the summer, visitors find the caves relatively dry at that time. In the winter, however, the passages will be veritably “raining” vadose water within a few days after snow or rain.

The water table itself is more stable, but varies somewhat from winter to summer, or during extended periods of unusually wet or dry seasons. Its lowest possible level is ultimately controlled by the elevation of the largest nearby surface stream or lake, which acts as a base level. When the streams and lakes are lowered by erosion, the water table of a given locality keeps pace by slowly sinking until eventually it lies scarcely above sea level.

Rain falling on the mountains above the cave seeps into the surface cover of vegetation and humus. Here it absorbs carbon dioxide released from the process of organic decay. Seeping further through the vadose zone and down to the water table, this water carries many times the normal amount of carbon dioxide found in the atmosphere. In fact, it becomes acid. For water (H₂O) and carbon dioxide (CO₂) unite to form a mild solution of _carbonic acid_ (H₂CO₃). In this manner, phreatic water is constantly charged with mild acids. Not the kind that harm us, of course. The fountain water by the chalet, and probably that in your home, is actually mild carbonic acid. So is bottled pop.

_SOLUTION_

RAIN + CARBON DIOXIDE = MILD CARBONIC ACID MOLECULES (H₂O) (CO₂) (H₂CO₃) CARBONIC ACID + CALCIUM = CALCIUM BICARBONATE SOLUTION CARBONATE MOLECULES FROM MARBLE STRATA (H₂CO₃) (CaCO₃) (CaH₂(CO₃)₂)

_DEPOSITION_

CALCIUM CARBON DIOXIDE, FOR EACH CARBON DIOXIDE MOLECULE BICARBONATE CALCIUM CARBONATE ESCAPING INTO CAVE AIR, AN REACHING CAVE EQUIVALENT MOLECULE OF CALCIUM AIR CARBONATE MUST BE REDEPOSITED AS SOLID DRIPSTONE, FLOWSTONE, ETC.

It was thus that phreatic water, charged with soil acids, percolated century after century through cracks in the marble. The acids ate away at all exposed rock surfaces—sideward, downward, and upward. (The solution rills in the original Ghost Room ceiling reveal the upward dissolving of water-filled cavities, see illustration page 9). To fully understand this, we must recall that the marble is 93 percent _calcium carbonate_ (CaCO₃). To dissolve it, carbonic acid mixes with the calcium carbonate to form an unstable liquid compound called _calcium bicarbonate_, (CaH₂(CO₃)₂). The removal of solid calcium carbonate in a liquid is the key cave forming process and is called _solution_ (see illustration page 10). In Watson’s Grotto we find several examples of early crack-widening by phreatic solution (see illustration page 9).

The enlarged cracks allowed faster movement of water against an increased surface area, and a subsequent increase in solution activity. Partitions between them fell apart and were dissolved. A series of water-filled passages evolved deep underground. Their pattern and orientation followed the pre-cave network of joints and cracks in the original strata. Gradually the openings were further enlarged into the cave system we know today.

There is more to it than that, of course. You may ask, “Why aren’t there caves continuously throughout the belt of marble? The joints and cracks are everywhere. And certainly all the marble near the surface has been subjected to ground water action at some time or another. Why are Oregon Caves limited to one particular part of the marble belt?”

The answer to this involves several considerations. To begin with, we do find small cavities and solution cracks throughout the exposed marble. So there has been varying degrees of solution activity nearly everywhere, although not sufficient to produce caverns comparable to Oregon Caves.

Secondly, we must reconsider the mineralized water, calcium bicarbonate. We called it an _unstable_ compound, meaning it will alter readily with slight changes in conditions. Once the amount of carbon dioxide dissolved in the water has united with an equivalent amount of calcium carbonate (marble), the solution is saturated. No more marble can be dissolved until additional carbon dioxide is absorbed by the water. If the solution loses some of its carbon dioxide into the air, then an equivalent amount of calcium carbonate must be redeposited as solid stone. The balance can be delicate. In an underground pool of mineralized water, _solution_ may be going on at one end of the pool and _deposition_ at the other.

So a state of chemical balance tends to develop in normal phreatic drift through the marble. Water saturated with minerals might easily move through many hundreds of feet of marble strata without further enlarging the openings. Instead, it might even deposit some of the dissolved minerals, filling small cracks and veins, possibly even blocking its own passage during dry cycles when phreatic flow is at a low ebb. The “dry” room in the cave is an example of vein filling. Clay, gravel, and other surface sediments can also be washed into the openings, plugging them up and halting further solution for a time. All these factors lead toward a stabilization of the solution process. Openings and small passages continue to be formed, yet normal phreatic movement at Oregon Caves seems to lack the force for large scale cave sculpture.

This opens the door to our third consideration; we know the greatest amount of solution occurs in the water table zone. Therefore, to gain the impetus needed to carve out a cave system, some local condition must have _increased the water table flow_ in the immediate vicinity of Oregon Caves. The solution process was magnified as larger quantities of freshly acidic phreatic waters were channeled into a restricted zone. Surging on, they scoured through the marble, dissolving larger volumes of calcium carbonate and sweeping it away. The early solution pattern of enlarged cracks had set the stage for the onset of this swift phreatic erosion. But some geologically sudden event was necessary to trigger the forces which completed the act.

We do not know exactly what the triggering action was. We know that the water table either received a _sudden increase in supply_ from surface drainage, or found a _larger or lower outlet_ downslope which tapped phreatic water over a widespread zone and channeled it through a localized area. There are several possibilities.

1. A perched water table may have been held in the cave zone by a lower and impervious layer of rock. This barrier may have been suddenly cut through by erosion, as if the plug were pulled in a bathtub. The perched water would now pass _through_ the barrier, rather than over it, evacuating parts of the former phreatic zone, and inducing surface streams to channel underground through the same route. With such a subterranean diversion of water from a higher to a lower drainage pattern, the water table flow would increase considerably. A cave-forming condition would exist.

Several small streams lose their identity and sink into the ground a few hundred yards above the caves. Doubtless, they join the water table inside the caverns to emerge at the entrance as the River Styx (called Cave Creek outside). Possibly they aided in the early stages of cave formation in a manner described above.

2. It is difficult to imagine what the surface topography was like when the cave was forming, yet we know it hasn’t always been the same. The mountains were higher. The streams occupied higher positions in the valleys. The ridges lay in a somewhat different pattern. Now and then stream piracy, or drainage rearrangement, took place when a rapidly eroding stream cut away the ridge separating it from a less active stream. Suddenly the slower stream was diverted into the drainage system of its captor. Both surface and phreatic waters of the aggressive drainage were increased. The flow at the water table speeded up in response.

If stream piracy occurred in the drainage overlying the caves, it might have played an important part in cave carving.

3. Nor can we omit the conditions that occurred here during periods of glaciation. Shifting masses of ice and glacial debris characteristically cause damming and rechanneling of water in minor stream valleys. The temporary results are similar to stream piracy. Coupled with this is the great volume of water which drains from melting glaciers. Evidence of partial glaciation in the Siskiyou Mountains lends serious consideration to its effect on early cave development.