Incomparable Carlsbad Caverns, in southeastern New Mexico, includes a
single underground chamber so expansive that its floor could accommodate
fourteen football fields and its ceiling could hold a 22-story building;
other chambers that contain countless cave formations of great variety
of shape and color; cool and naturally circulating fresh air; and a
system of lighting that reveals the beauty and spaciousness most
effectively.
Since the temperature within the Caverns remains at about 56°F the year
round, warm clothing is needed. Comfortable shoes, too, for the
four-hour, three-mile complete tour, which starts at the natural
entrance. Shorter trips, the Big Room tours that start at the elevators
in the visitor center, take in only a part of the underground chambers.
All tours are under leadership of competent park guides who answer
questions and explain the earth processes that have resulted in the
caverns and their amazing decorations.
From the natural entrance, the immense main corridor of the Caverns is
followed downward 829 feet for one and three-quarters miles. This brings
visitors to the most scenic rooms (the Green Lake Room, King’s Palace,
Queen’s Chamber, and Papoose Room), where the stalactites, stalagmites,
and helictites reach their peak in numbers, shapes, and delicate
coloring. The trail leads upward 80 feet from the Papoose Room to the
lunchroom. Near the lunchroom is the Big Room, the most majestic of the
Caverns’ chambers. The trail around its perimeter, one and a quarter
miles long, encompasses a floor space of fourteen acres.
[Illustration: Hall of Giants in Carlsbad Caverns National Park]
Completing the circuit of the Big Room and returning to the lunchroom,
visitors may either walk or board an elevator and ride smoothly back to
the surface.
How were the Caverns formed? The story began about 240 million years
ago, during the Permian Period. At that time, the two limestone
formations in which the caverns occur—the Tansill Formation and Capitan
Limestone—were deposited as part of an organic reef complex at the edge
of a warm shallow sea.
During subsequent periods, other seas brought in sedimentary material
that covered the reef. About 60 million years ago, earth movements,
which were responsible for the uplift of the area, fractured the reef
and permitted surrounding ground water to enter along fracture lines and
begin work in fashioning the caverns. The water at first dissolved small
crevices in the limestone. As more water came in, the crevices enlarged
to cavities, called solution pockets. Then the walls, floors, and
ceilings of the pockets dissolved and collapsed, joining the pockets,
while the solution process continued, eventually forming the huge rooms
seen today.
Beginning about 3 million years ago and into recent times, the uplift of
the local Guadalupe Mountains and changing climates lowered the water
table. Water that had been inside the caverns drained away and was
replaced by air. Most solution stopped, but large sections of partly
dissolved walls and ceilings collapsed under their own weight. Stability
was finally achieved, however, and probably no rock has fallen within
the caverns during the last several thousand years.
Even before the collapsing ended, another phase of cavern development
had begun. Rain water and snow melt slowly seeped into the caverns.
Droplets of water, each holding a minute quantity of dissolved
limestone, appeared upon the ceilings. Exposed to the air, the droplets
evaporated and left their mineral content as calcite and
aragonite—crystalline forms of limestone. Over centuries, this process
of evaporation and deposition has built a myriad of crystalline
stalactites of all shapes and sizes. Water that dripped to the floor
evaporated and deposited the calcite and aragonite to build stalagmites.
When joined together, stalactites and stalagmites become columns, or
pillars. In the scenic rooms, conditions existed that brought about the
creation of helictites—twisted formations that seem to defy gravity in
their growth. Color in the cave formations, shades of brown, red, and
yellow, result from the presence of small amounts of iron oxide and
other minerals.
Carlsbad Caverns National Park offers more than the caverns themselves.
Each evening from April to October, bats in incredible numbers spiral
upward out of the Caverns’ entrance and fly southward over the rim of
the escarpment to feed in the valleys of the Black and Pecos rivers.
They return just before dawn, diving swiftly and from high altitudes
into the entrance. Flying directly to the bat cave, they spend each day
hanging head downward in dense clusters from the walls and ceilings. The
bat cave itself is not open to visitors. A park naturalist explains the
bat flight and discusses the bats in detail in a talk given at the
entrance to the Caverns each evening before the flight begins.
The nature trail, a half mile loop that begins and ends near the
entrance to the Caverns, guides the visitor to many of the desert plants
of the region. The park is visited by more than half a million people
each year, and yet the delicate cave formations and the natural beauties
remain unmarred.