Carlsbad Caverns National Park

Standing atop a high point in Carlsbad Caverns National Park, you survey an arid land of purple shadows and gray-brown rock. Southwestward into Texas rise the Guadalupe Mountains, and your eye follows the line of the ancient seacoast that gave them birth. In steep-walled canyons, carved long ago by rushing water, deep rock layers are laid bare, a few so sharply tilted that you can almost feel the force of these mountains' upheaval. Northward, and all around, is the high New Mexico desert, a harsh landscape of mesquite and scrub, enlivened by agaves and abundantly varied cacti. Rock wrens flit through the low brush and into crevices; vultures, hawks, even golden eagles, glide and soar.

With the hot sun on your back, it is hard to realize you are standing over a deep, cool, wonderland of stone, where the temperature varies little from 56° F, where the only light is man-made, where growth and change are measured in millimeters per century, where magnificently ornamented cliffs and canyons filled with surreal sculpture dwarf the outside landscape. It is harder still to see a correlation between the lively beauty around you and the silent, lifeless beauty far beneath your feet. Yet the changing nature of the aboveground world is responsible for the drama under way below.

Just as rushing water has the power to cut through stone, so can slow-moving water eat away solid rock. But slow water can also replace that rock, one drop at a time, with equally solid new rock in shapes undreamed of by human sculptors. It is the results of this drama of water gradually replacing rock with rock that we see today in the vast underground theater of Carlsbad Cavern. The performance was majestic and incredibly graceful, more intricate than any ballet, with a grandeur that the grandest opera cannot touch.

We are late arrivals at the show, having come in partway through the third, and probably the final, act–an act that has been in progress for more than a million years. The play itself began perhaps 250 million years ago, long before birds flew, mammals walked, or flowers bloomed across the earth.

Act I–the building of a huge limestone reef along the edge of an ancient sea–was performed by tiny lime-secreting algae and other primitive marine creatures, many of whose bodies also became part of the reef. Generation after generation, these beings lived and died and added their substance. The sea itself added a limy mineral cement, and eventually the reef rose high enough to isolate a calm lagoon between the ocean and the shore. Before the act was over, the reef stood hundreds of feet high and up to four miles wide in places. The floor of the lagoon it protected, continuously fed sediments by streams and rivers, was rising steadily.

When the ocean eventually withdrew, leaving behind salty mineral deposits, the reef died. Its burial was slow. On the lagoon side, sediments continued to rise until the lagoon was no more. Then streams spilled over onto the seaward side and sediments built up there. The 100,000,000-year-long Act I had come to a close.

After another million centuries or so, during which sediments hundreds of feet thick accumulated above the limestone reef, Act II began. The plot was violent. The earth shuddered, and mountains arose. In a tremendous convulsion, part of the reef was broken off and thrust upward, to become the Guadalupe Mountains. This was no overnight occurrence; the action began here about 15 million years ago and has continued until quite recently, geologically speaking.

As the water level declined and the reef arose, groundwater seeped through cracks deep inside the limestone, softening and dissolving the rock. Water-weakened sections, unable to support their own weight, fell. The reef became honeycombed with chambers, varying in width from less than an inch to a thousand feet. Walls dissolved and disappeared, and water-filled rooms became caverns. When the water level dropped still farther, leaving spongy rock masses unsupported, great chunks fell. The reef became honeycombed with chambers, varying in width from less than an inch to a thousand feet. Walls dissolved and disappeared, and water-filled rooms became caverns. When the water level dropped still farther, leaving spongy rock masses unsupported, great chunks fell. By a million years ago the upper caverns were dry, though seepage still continued below. Act II–unseen by any eyes–was at an end, and the underground stage was set for Act III, in which severe rock walls were to be adorned and decorated, transformed into the world's most beautiful cave.