Travel - Carlsbad Caverns National Park

Carlsbad Caverns National Park is a large cave complex in southeastern New Mexico, outside the city of Carlsbad.  In the right season, it is also one of the largest migratory bat colonies in the world, and the bats are supposedly what led to the exploration of the cave in 1898.  The place appeals to me for a number of reasons - the story of its exploration, the geology, and the beauty of the setting, in no particular order.  This was not my first visit to the park, though it was the first under COVID restrictions.  The extent of Carlsbad's COVID response deserves some discussion, and it is something that every visitor needs to be aware of before going, so I will address it first.

Carlsbad is easily the largest destination of any that we visited; on a previous visit, its off-season crowds looked like any of our other destinations' spring-break crowd.  In a good year, the cave system has multiple guided tour options and bat flights, and the park is a dark sky destination.  COVID has restricted all of these to a greater or lesser extent: back-country permits are harder to get in general, bat flight viewing is suspended, and ranger tours are suspended.  In addition, visitor center access is reduced.  It is not as tightly monitored as Guadalupe's was, because the multiple entrances and exits to the building make monitoring more difficult, and spacing is not strictly enforced inside the visitor's center, though, as a federal facility, it is still under a mask mandate as of this writing.  Access to the caves themselves are by online reservation or by a very small number of walk-ups, and because getting in the door itself is controlled to get to those walk-ups, or to get to the ticketing desk, showing up early is hands-down better than having a lazy day.  Access is further complicated by the fact that the cave paths are narrow and maintaining two-way traffic and social distancing would be impossible, so traffic is one-way.  Until 2:30 in the afternoon, that way is down, then up via elevator; at 2:30, entrance to the cave ends, so anyone willing to climb out can do so.  I will discuss climbing out in greater detail later; it suffices for now to say that it is a challenging walk.

Now, on to the caves themselves!

Last point of natural light, Carlsbad Caverns

Carlsbad is buried in the same Permian limestone formation as Guadalupe Mountains National Park; the two parks are in fact so close they function as one administrative unit.  It was formed by hydrogen sulfide from petroleum deposits leaching up into the water supply, forming sulfuric acid and dissolving the limestone.  Once sufficiently large voids formed, the water was able to do its own slow dissolution and material transfer, and more conventional erosion by seepage helped link the smaller voids into larger chambers.  This is all terribly boring to most people, but it's fascinating to me.  I'm used to limestone formations in very different conditions, known as karstic topography, where the erosion happens mostly top-down rather than bottom-up as happened here.  Karstic behavior is part of why there are some massive boulders that fell from the ceiling in Carlsbad - water moving through fissures widened those fissures, until boulders the size of apartment buildings broke loose and crashed down into the caverns below (although I should point out that such collapses haven't happened in recent geologic time, meaning "since recognizable humans existed").

In any case, once the voids had formed, the water table dropped (repeatedly - there is a layer-cake of caves in there, with at least three separate periods of sulfuric erosion).  The two facts, voids forming and water table dropping, are not necessarily connected, though larger voids mean more space for pore water, so the odds are good that they are at least partially related.  Thus, water moving through the rock was exposed to air and able to evaporate, meaning that the calcium carbonate carried in the water gets deposited wherever evaporation took place.  This is the source of the fantastic formations in the Great Room, where most tourist activity takes place.

The Big Room, on entry from Natural Entrance.  Head at bottom is not a garden gnome, I promise.

Carlsbad is a good place to learn basic speleothems - the shapes of things that happen in caves - as it has experienced pretty much every depositional or erosional environment possible in a limestone cave.  The interpretive stations explain much of this, usually in more than one place so that someone who missed the first time can find it a second and occasionally a third.  Missing a sign is almost to be expected, because there is a lot to see, just in the public-access sections.  Most of the formations have been named by now, but even so, we found ourselves assigning names to formations in order to have reference points.  For instance, there is a trio of formations squatting above the Fairy City that almost instantly got called the Cave Guardians, because of the way they hunch down over the lower formation.

Foreground - Fairy City; Background - "Cave Guardians"

 

The Fairy City is an incredibly elaborate series of "popcorn" deposits, caused by water evaporating over an uneven surface, while the "Cave Guardians" are a trio of stalagmites, no longer active as water flows through other channels, but each one bears signs of growth cycles.  Above, stalactites form vast galleries of chandelier-like structures, which at least a couple of us found a little unnerving to walk beneath.

After touring the Big Room, we stopped by the lunch counter and lower gift shop and got sandwiches in preparation for the hike back to the surface.  The sandwiches were unexceptional, save for the setting, which felt a little like eating lunch in the Führerbunker and meant that everything we ate had been hauled down from the surface.  Alas, as described earlier, the Natural Entrance is one-way throughout the day, and we weren't delaying until 2:30, since we still had to drive back to Texas.  Instead, I will describe it from previous experience.

The Natural Entrance is about a mile and a quarter long and ascends 750 feet over that run.  In other words, it ascends about fifteen inches for every ten feet of ramp length.  This does not sound too bad, save that those grades are not even, that 12.5% grade is an average, and a 10% grade, or one foot for every ten feet of ramp, is considered a reasonable upper limit in road construction - past that and pull-outs or runaway truck ramps are common.  This is also the case on the Natural Entrance, which features frequent stopping points or logical resting points, with benches located where they can be.  This is for the best.  Since a standard building story is about ten feet, the 750-foot climb is equivalent to climbing 75 flights of stairs - not a task for the faint of heart or the ill-prepared.  It is not the steepest hike I have ever done, but it is over an extended period, sucking down remarkably humid air that, even if it is pleasantly cool, is still several thousand feet above sea level.  The first time that we did it, my wife and I basically rested every time a switchback turned left.  The Park Service recommends an hour for this hike, and paved or not it is a hike.  I would vouch for that recommendation.

All in all, Carlsbad Caverns was well worth extending the trip by two days, and my only regret about it was not being allowed to throw myself back up the path to the surface again, instead having to use the elevator.  Being able to come from the dark, dimly lit depths up to the bright-blue of the Guadalupe Mountains on a clear day was an incredible experience all its own, as was pointing out to the kids that if you stood just so at the visitors' center, you could see where we had been hiking just a few days previous.  Especially as the elevators are accessible and available, pretty much anyone can access it (I took a pair of seven-year-olds in, for instance).  I look forward to the resumption of ranger-led programs so that I can do some of the off-path caves at some point in the future, but for the moment, it was well worth the visit.