Arches and Fins

Arches and Fins

    In the last post, I meant to talk about the fins, best described by the graphic from the site of Arches National Park in southern Utah.  These fins (if you watched the video) are eroded away over time and while they might look small, when you are walking within them you can only stare upwards in awe.  It is rather like facing the threat of being crushed should they begin to move (for you fans of the early Star Wars).  Here's the park's simplified description: Rainwater dissolves sandstone, widening cracks to form fins.  An alcove eroded in the base of a fin might grow to form an arch before finally collapsing.  Arches National Park has the densest concentration of natural stone arches in the world.  There are over 2,000 documented arches in the park, ranging from sliver-thin cracks to spans greater than 300 feet (97 m).  How did so many arches form?

Graph from Arches National Park website

    Remember back in the day when I mentioned an early geology lesson, that rock formations are named for the city or area they were first discovered or were most prominent?  Hmmm, well, keep that in mind as you read what their site goes on to explain: Sandstone is made of grains of sand cemented together by minerals, but not all sandstone is the same.  The Entrada Sandstone was once a massive desert, full of shifting dunes of fine-grained sand.  The grains are nearly spherical so, when packed together, they formed a rock that is very porous (full of tiny spaces).  In contrast, the Carmel layer just beneath the Entrada contains a mix of sand and clay.  Clay particles are much smaller than sand grains; a lot of them can pack together and fill in gaps between the sand grains, making the rock denser and less porous than a purer sandstone...Deep beneath the surface lies a thick layer of salts.  Squeezed by the tons of rock above it, the salt flowed and bulged upward, creating long domes.  The rock layers covering these domes were forced to crack, like the surface of freshly-baked bread, into a series of more-or-less parallel lines...On average, the park receives 8-10 inches (18-23 cm) of precipitation a year.  That might not sound like much, but it's enough to keep the engines of erosion working 24 hours a day, 365 days a year...Drops of rainwater soak into the porous Entrada sandstone easily and then slowly dissolve the calcite bonding the sand together – in other words, rotting the rock from the inside out.  Water puddles just above the denser Carmel layer where it erodes a cavity, like food trapped between your teeth.  In winter, water trapped between the two layers expands when it freezes and pries the rock apart...If the park received too much precipitation, the sandstone could erode so quickly that arches might not have time to form.  If it never rained here, the engines of erosion would stop.

Photo by Casey Shreiner of Modern Hiker

    Arch formation.  A few decades ago, I ventured into the Devil's Garden*, an area full of fins and one even the park advises, "Narrow ledges, exposure, steep climbing, and few trail markers on Primitive section...Not recommended when wet or snowy."  But the trails were just outside the campground, I was much younger and more importantly, that alternate-universe voice still echoed in my head "how bad could it be?"  And with well-equipped pack in hand (which was more than most people had, from what I saw...of course, all those people stopped and turned around much sooner than I did), off I went.  If you've ever been there, here's how it happens...you begin walking along a nicely paved footpath which soon branches off into a series of deeper dirt paths (the paved portion veers off, which is where most of the people go for the quick loop).  The dirt paths lead you ever deeper into the fins, walls of rock which only seem to multiply and grow and soon, you are in the midst of not several fins but several dozen towering fins, each looking pretty much like the other.  Soon, looking back at the path I had traveled, the fins looked the same in that direction as well...I was lost.  Now in the Devil's Garden (who would name it such a thing...although once lost, I found the name quite appropriate), there are few people who will notice you missing for tents are everywhere back at the campground and who bothers checking on a closed tent?  When it's time to leave you just pack up and go and a new camper arrives and wonders why their tent-neighbor is such a recluse and rarely emerges...at least, those were my thoughts as I pondered which way to turn.  Then, a wash, one of those docile-looking sand-filled water runoffs that the park service always tells you not to enter until you know the weather conditions upstream; should a storm hit, even many miles away, you might face a torrent of rocks and logs heading your way with full force, a tidal wave of sorts that can be far stronger than a simple stream filling up.  Plus, this wash was a one-way jump down; once I took the leap, there would be no climbing back out.  As the song says, should I go or should I stay?

    Then, a cairn.  For those of you non-hikers, these are simply a pile of rocks stacked more or less in the shape of a pylon and used as a marker guide;  on remote trails, you can sight-line these piles up and it will prove a safe path when it seems none is there.  So, from my ledge, I looked and looked, and off in the distance (well away from the wash, obviously), I thought that I saw a cairn.  But was it?  Or was it simply a random pile of rocks that looked like a cairn?  Go for it or face an uncertain return back and possibly get even more lost (did I mention that in certain areas such as the park's Fiery Furnace, hikers are told not to travel without a ranger guide due to "solid" domes that are anything but and can collapse once stepped upon)?  Being younger and full of in-experience, I made the jump and headed for the cairn...quickly.  And it was, a cairn, that is...then another, quite a bit ahead.  Before long, due to my concentration on the cairns, I was climbing uphill and then...the paved path!  Of course, my young bravado quickly returned as I waved to the few people still walking the path (it was now dusk and the light quickly fading).  No big deal, I told myself.  Knew it.  But in reality, I didn't know it.  Just minutes earlier I was hoping that I had packed my emergency blanket and fishing line and elastic bandage and such, each of them never used...but you never know!  And this was 20 years before Bear Grylls and such get-lost-on-purpose adventurers.

    Bear in mind, this is only my memory of it, meaning that perhaps all of the park's paths have changed and they've now paved everything (which also likely means that they've finally found the bones of all those who got lost like me and decided to do something about it).  The point being, we all wander at times into fins, sometimes by choice and sometimes not so much.  With my mother, navigating her path of insurance and her roller-coaster ride of mobility and mental acuity often seems to send me back into those fins.  At times I feel quite lost, puzzled at a new terrain that (for the most part) I am not prepared for.  But glancing far ahead, perhaps just visible through the fog or at the edge of your sight, there will likely be a cairn.  It may be a friend or a relative that has gone through this ahead of you, perhaps even a group of people...not rocks, but at a time down the road, they will likely prove to be rocks, guides that have stoically got you through to safety.  Follow those cairns, even the small ones that might seem washed away.  They have blazed the path ahead of you, taken the risks, and taken the time to go back and help others.  And as you go, perhaps unaware to even you, you might find that you've placed a small rock of your own on the path, the beginning of a path you're leaving for others.

*An updated view of the current hiking conditions and paths can be found in an article by Casey Shreiner, editor of Modern Hiker.