Caving in Montana: Crystals Galore

These are well-known caves that are publically accessible with a permit. If you would like more information, or would like to view any of my site-specific references, please feel free to send me an email at helena.heliotrope at gmail.com. If you’d like to visit the caves, please contact the BLM Field Office in Cody at 307-578-5900, and ask about their caves!
In the fall of 2009, I got to go on an epic caving weekend near the Montana-Wyoming border. I talked briefly about some interesting chert nodules here, but I was honestly holding out on the best stuff: the formations.
The caves here are formed in the limestones and dolomites of the Madison group. These rocks formed between 360 to 325 million years ago, in the Mississippian, when a relatively tranquil, shallow sea covered the area. Like most seas, this one was filled with small organisms that had calcium shells or skeletons (such as corals or amoeboids.) When these organisms died, their decaying corpses were slowly compressed into limestone. Above the limestone lies a layer of reddish sandstone called the Amsden laid down in the Pennsylvanian, visible as the red streak in the above picture. After undergoing a sequence of uplift and subsidence, it was uplifted to its current level during the Laramide orogeny, about 70 million years ago. This created joints in the limestone that would someday become caves.
(It’s a really structurally interesting area – some of the nearby mountains are uplifted in a giant anticline, while the ones in the above picture are fault blocks that were tilted upwards.)
The Madison group stretches from South Dakota to eastern Idaho, and from Canada down into Colorado and Arizona, although the name differs regionally. Since limestone is very soluble, it’s chock-a-block with caves, including Lewis and Clark Caverns in Montana. Because of its solubility, it forms a very important aquifer, and has produced a prodigious amount of oil – over 1,400,000,000 barrels. (Pretty impressive for a bunch of dead sea critters!)These caves were eroded as the basin lay beneath the water table, in a process called phreatic erosion. Phreatic erosion occurs as the water flows through cracks and joints, eroding passages through the limestone. This passageways travel in all directions: the above photo shows a vertical, cream colored passage cutting through different bedding planes. Additionally, we saw some collapse along bedding planes, which created some fantastic flat roofs, visible here in the greyish section. Dating caves can be difficult (much like men), however some ash found in these caves is from an Yellowstone eruption 640 thousand years ago.
(I apologize for the poor picture – it’s quite difficult to take decent photos of large cave rooms without secondary light sources.)
This is a trace fossil we found on one of the bedding plane ceilings – it’s where a sea creature was burrowing, or eating, or squirming along. (The paleontologist on the trip provided some more details, but I’ve unfortunately forgotten.) I had never seen a fossil in the wild before, so this was one of the trip’s highlights.
The first cave we went to is the most challenging cave I’ve been in so far, despite being entirely horizontal. The entrance is through a 100’ long crawlway – which sometimes is only 15” tall. (I definitely got stuck a couple times!) The floor of this crawlway is thickly coated with radon-laden dust: to avoid developing radioactive cavers, the BLM limits the time you can spend in the cave each year. We wore dust masks, to cut down on the amount of junk we inhaled, but that only served to make me more claustrophobic.  This was even more heightened by the heat – it was the warmest cave I’ve ever been in. It was a pretty rough beginning, but we were richly rewarded for all that effort with masses and masses of my favorite formation – helictites.
I didn’t have my camera that day, but I did the next day, when we visited the second cave. The day of this trip, snow was predicted, so we only spent the morning underground. (The road to the caves requires a 4wd vehicle generally, but is reportedly impassable in bad weather.) Luckily, as we ascended out of the cave right as the snow began falling, and made it to paved roads just in time.
The caves have a wide variety of calcite formations, including helictites, rafts, and some really large cave popcorn. Additionally, they have gypsum flowers and crusts, epsomite crystal curls, and aragonite needles. These all form near each other, making for some truly impressive photographs.
This last photograph is an interesting chunk of yellow and red crystal crust that was forming in a hole in the ground. I still don’t know what it is…
This is the underside of a rock, absolutely encrusted with black crystals.
As we headed back to civilization, there was an antelope hanging out, clueless about what lay beneath its small cloven hoofs.

Montana, Chert, and the 1960s.

Two years ago, this rock really caught my eye while I was caving in the Madison Group of Montana.
First of all, there’s a nifty calcite or gypsum encrusted pocket, which looks much like a sparkly pothole…

(My assumption is that this formed as water seeped through the limestone into a small hole, and then crystallized on the hole’s walls.)
Then there’s the missing chunk, which gives a nice look at a crazy banded chert nodule.

If that chert nodule embodies John Lennon’s “Magical Mystery Tour” era, this nearby chert nodule is more Jackie Kennedy:

Way to keep it classy, chert.

2010 Travel Meme: The PNW Edition

This travel meme seems to be a geoblogosphere favorite! This year, Silver Fox started it, and has a list of this year’s participants. I’m a little late, but better late than never, eh? In 2010, I visited a mere 4 states – but lived in 3 of them!

In January, I hiked up Mt. Si with my family and some of my mum’s caver friends. It was a little chilly at the top, but what a view! Also, my family took a day trip to the Portland Art Museum (and Voodoo Doughnuts!) At the time, I lived in Olympia, Wa. (The state capital, 2.5 hours from Seattle, and the hipster-little-sister-city to Portland, much to the chagrin of Olympians everywhere.)

In February, I went to visit Oregon Caves National Monument with the Cascade Grotto for a conservation weekend. I picked some lint, but my father and another power-tool devotee removed a large piece of metal from the cave, dangling on rope, wielding reciprocating saws.

In  March, my friend Sarah visited, and we went on a lovely lake hike with her mum near Brown Creek.

Also in March, I visited Discovery Park in Seattle with my school’s geology club. We looked at the glacial deposits there, including the Lawton Clay, Esperance Sand, and the Fraser till. Underneath all the glacial deposits lie the pre-glacial, river-deposited, and highly photogenic Olympia Beds.

In April, I visited Elliot Bay Book Company in their Pioneer Square location, the day before they moved to a new location in Capital Hill. There was a reason – high rent or some hogwash – for the move, but I think the new location is fugly compared to the creaky wood floors and dark, brick-lined basement café. Pfft.

In May, I visited the Columbia River Flood Basalts twice: once on a geology club field trip, where we visited Dry Falls, Grand Coulee dam, and went on a geology hike…

… and once on a Northwest Geological Society field trip, focusing on structural geology. I haven’t studied much structural geology yet, so this basically blew my mind, especially this scenic anticline. Overall, it was a pretty basalt-tastic month.

In June, I had a fun-filled four-finals week, and then packed up my apartment and moved to South Idaho. On the way, I swung by the John Day Fossil Beds in Oregon.

In July, I was busy travelling around Idaho, doing an internship at Craters of the Moon.

In August, I went to north Idaho for a trip through Papoose Cave. We rappelled down a 22’ waterfall, but, unfortunately, the 40’ waterfall had too much water to rappel through. We got to see some great limestone during the short trip, but no formations.

After that, my sister and I took a trip to Yellowstone, where we saw hot springs, microbial mats, and a bunch of animals.

In September, I went to the Northwest Caving Association Regional in Bend, Oregon, and saw even more lava caves (and some long tree roots!) Then I finished up my internship and moved back to my parent’s house in the Seattle/Tacoma suburbs.

In October, I went on the annual bike riding / wine tasting trip in Eastern Washington with my parents and their friends. (I always hope for some hilarious middle-aged drunken hijinks, but they’re all too wise for that nonsense.) Also, my brother graduated from Universal Technical Institute in Phoenix, and we went to see him and his wife. During the plane ride, I got a great aerial view of some nearby volcanoes.

The day after returning from Phoenix, I moved my possessions into my parent’s van, and drove down to Oregon Caves to work on a restoration project.

In November, we visited Crater Lake. We went home to Washington for Thanksgiving, and then returned to the caves for more work.

In December, we travelled back to Washington. Before that massive snows and a power outage made life a little adventurous, but we got to have an active lesson in static and kinetic friction, and how the coefficient of friction of ice is different than that of pavement. Sometimes this was bad…

… but sometimes it was pretty useful.

On our way back, we visited some of the historic covered bridges in Cottage Grove, Oregon.

Before the New Year, we visited Seattle three times. (My mother likens these shipping cranes to Brachiosauruses.) We did a toursity gig – the ballet, Pike Place Market, the waterfront… It was really nice to visit the city a couple times before I move to Boise next week.

Here’s hoping 2011 has some more travel adventures, and that everyone had a happy New Years!

Two-sided Dike

This is one of my favorite cave features here at Oregon Caves National Monument. It’s a quartz diorite dike encrusted with calcite.

Water (carrying minerals) flows through cracks in the marble bedrock. Quartz diorite is less permeable than marble, and when the water is unable to seep through. Instead, it flows down the surface of the dike, coating one side with calcite formations.
This is my favorite example of this, but there’s a much more prominent one along the tour route, so you should visit sometime!
If you’d like to learn more about the caves, you should read Ranger Gaelyn’s fantastic cave tour part one and part two!

Boil, Boil, Toil and Trouble: Lava Cave Features

 

Lava tubes frequently show fantastic features, and I saw some really cool features while I was interning through the GeoCorps Program with the BLM at Craters of the Moon National Monument and Preserve. Some of the more decorative formations are the result of boiling gases inside the lava. Honestly, I hadn’t seen many of these formations before this internship, so it was very exciting!

It was interesting to learn more about lava: how the tube walls themselves cool, how secondary flows erode the original tube, how both cohesiveness and fluidity contribute to form features, and how the pressure in the flow creates different landscapes (like pressure ridges and tumuli.) Being able to observe a great quantity of lava over the course of three months was highly educational - even if I can’t cite lava facts of statistics, I know more about the characteristics of lava by seeing so much of it.

I know I haven’t given much information on the region’s geology itself, but that’s because I get too darned excited about lava tubes.

As the ceiling of a lava tube is cooling: first the exterior layers, and then the interior. Once the exterior layer has begun congealing, gases in the interior lava can boil, squeezing lava out through the exterior layers. (Kind of like a pasta machine.) As this lava drips down, the sides of the drip cool, leaving the liquid lava inside. This liquid lava can then flow to the bottom of the stalactite, creating a hollow space. Sometimes the last bit of the drip falls off the stalactite, other times it plugs the stalactite up. The left picture shows some stubby stalactites from Craters of the Moon, and the right picture shows some really delicate “soda straw” stalactites from near Mt. St. Helens.

If the lava inside these stalactites drips onto the ground, it can pile up to form a stalagmite. I didn’t see many in Idaho, but the ones I did see were really tall. Unfortunately, I didn’t have a camera that day, but I also saw some good ones in Bend this summer.

These are called “stalagpies” by the local cavers, but are more widely known as lava roses, especially when they have a clearly defined series of concentric rings. I think they look a bit gross, but they can form in a really nifty fashion: when lava boils from under a semi-cooled floor, the pressure of the gases pushes the lava up through the floor. As a result, these are also sometimes called “lava volcanoes.” These are identifiably by their “central conduit,” which can be easily seen in the bottom picture. These pictures are from a lava lake, so this explanation makes sense.

Because these don’t have a conduit, I think this is an example of the other way in which lava roses form: when larger clumps or sheets fall from the ceiling, and pile up, cooling, slumping, and cracking as they do so. (I think the right one is especially ugly – it resembles a miniature Horta.) These pictures are from a different cave than the previous lava roses – so a different origin is plausible.

These are lava helictites! These are created in a manner similar to the lava stalactites above, but the lava is pushed through weak spots in the developing crystal structure, forcing it into a twisted shape. Both lava and calcite helictites refuse to obey gravity.

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References:

If you want to learn more about lava caves and their features, here are some great resources:

The Virtual Lava Tube is an easily accessible resource, complete with beautiful pictures. This site is run by Dave Bunnell, editor of the National Speleological Society News. He also published the information in a book called Caves of Fire: Inside America's Lava Tubes, which is gorgeous.

Nomenclature of Lava Tube Features is an older article, but describes a greater number of features than the Virtual Lava Tube, including many different types of stalactites and pahoehoe lavas. It’s available in print form in the proceedings of the 6th International Symposium on Vulcanospeleology, and in illustrated form as An Illustrated Glossary of Lava Tube Features. (I wish I’d found the online copy earlier – I accidentally left my print copy in storage!)

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An aside: nothing I say on this blog represents the opinion of Craters of the Moon National Monument and Preserve, the BLM, the NPS, the Geological Society of America, GeoCorps, or the National Speleological Society and its internal organizations. I will not disclose any cave locations, but if you wish to go caving in Idaho, please visit Craters of the Moon National Monument (NPS,) the Shoshone Field Office (BLM),  or get in touch with your local caving club.

Summer GeoCorps Internship: Or, Caveapalooza 2010

This summer, I was an intern at Craters of the Moon National Monument and Preserve with the Bureau of Land Management in Idaho, through the Geological Society of America's GeoCorps Program.
It was a fantastic experience, but I haven’t previously discussed it here mainly because of uncertainties regarding legalities and whatnot. (My mum’s a lawyer: paranoia is in my genes.) So, let it be stated: nothing I say on this blog represents the opinion of Craters of the Moon National Monument and Preserve, the BLM, the NPS, the Geological Society of America, GeoCorps, or the National Speleological Society and its internal organizations. Caves are a federally protected resource, and thus I’m not going to disclose any cave locations, names, or, really, more information than is necessary.
If you are in south Idaho and would like to visit wild lava caves, that’s great! First, get your gear, read up on White Nose Syndrome, and then visit the Shoshone Field Office to request a list of caves open to the public.

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All that might seem kind of stern, but this is what happens when caves are destroyed:

The left picture is from a cave heavily vandalized for its entire length, most of it vile in content, all of it lacking in artistry. The right picture shows detritus left behind by people who were clubbing and shooting pigeons in a cave; we also found two dead barn owls this summer. During my internship, several damaged cave gates were discovered as well: not only is this blatantly disrespectful, but also incurs an expenditure of governmental time and money, and frequently results in other cave damage.
Should someone committing acts of this nature be found, legal action can be taken against them under the 1988 Federal Cave Resources Protection Act. FCRPA states, essentially, that caves are super-awesome resources that should be protected, through inclusion in federal land management planning and communication between land management officials, cavers, and visitors. It also outlines punishments for those who damage or remove items from the cave: up to one year in prison and a fine for first time offenders, and up to three years for second time offenders. (Since many cave restoration projects take longer than this, I think this is a pretty light sentence.)
Rampant destruction of a sensitive and delicate ecosystem annoys the crap out of me. Not only is cave vandalism destructive to life-forms, but it also damages scientifically valuable features, cultural artifacts, pollutes aquifers, and ruins the cave for other visitors. In addition, partying in caves is unsafe – I watched a sober, helmeted person get a concussion this summer. The addition of booze, much less drugs, could create a much more serious situation, and result in a risky rescue situation. Also, it should be noted: caves don't clean themselves – someone else has to.
Cave vandals make me irrationally angry.

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Craters of the Moon is run jointly by the National Park Service (NPS) and Bureau of Land Management (BLM.) My position was with the BLM, and focused mainly on cave conservation: completing the process to ensure legal protection under FCRPA, placing outreach/educational signs, and conducting cave surveillance. Additionally, I met the local caving club (grotto) members, led several tours through the caves, compiled a long-winded informational guide for interpreters, and found caves whose locations had been lost.
I thought that, in the next couple of posts, I’d share some of the cool things I saw and learned this summer. Frequently, caves seem to be misunderstood, feared, and ignored by the general public: this is a shame, because they’re really scientifically valuable, and provide recreational and educational opportunities for people of all ages, sizes, backgrounds, and experience levels.
(Unless otherwise noted, these pictures are from Craters of the Moon.)

The most common process for a lava tube’s formation is thus: a smooth, laminar flow of pahoehoe lava travels across a landscape with a certain slope – not too steep, or it will turn into a’a lava, and not too shallow, or it will fail to flow. (I’ve been told between .5 and 1.5 degrees: the validity of this is uncertain, however.) Frequently, these lava flows will form channels, as seen in the above picture from Jordan Craters, OR. As the lava flows in these channels, it begins to form chunks of crust: these raft along the flow, stick to the sides, and bunch up against one another. Eventually, a roof is formed over the channel: this continues to cool and thicken, while the lava underneath is still flowing. Frequently, the lava in the tube will cool and block the tube; if the flow is diverted or ceases, the lava may flow out, leaving behind a lava cave.

As the lava cave cools, the molecules in the lava are pulled towards one another, causing the lava to cool and contract. (This is standard for all liquids as they freeze, with the notable exception of water.) As it contracts, cracks form: it you’re lucky, a spot in the cave roof is weakened enough to collapse. This creates skylight entrances into the tube, like the ones in the above picture from Lava Beds, CA. (Skylights can also be formed when a section of roof fails to cool, although I have yet to see an example of this at a lava cave.) Skylights provide access to the cave for both organisms and cavers.

This is a good example of a primary lava tube: it has a simple oval shape, indicating that a secondary flow hasn’t travelled through and eroded the floor. This cave also had very few features, which can indicate that there were few lava flows in the tube. In places, we saw chunks of pahoehoe that stuck to the walls as the flow cooled; however, the majority of the floor was thickly covered with fine sediment. Uptube, it was possible to see where loess from the surface was washed in with small rocks: these quickly settled out, and, at the downtube end, blocked the passageway. We followed an old record to this area on my last field day, and it really panned out: we found seven caves, all erupted from the same vent. It was a pretty great way to end my internship.

This is the granddaddy of caves in the area: it’s the longest, and contains some really unique features (and some Silver Sage Grotto members for scale.) On the left, you can see an area where a secondary flow travelled through the cave, thermally eroding down the floor in the process, and thus increasing the tube’s height. This picture also shows a feature called benches/curbs/ledges: these show that a secondary lava flow travelled through the original tube, cooling onto the sides in the process. Benches frequently are characterized by their rectangular cross-sections, but they can have different shapes: in the right picture, you can see how there are benches stacked atop one another, and undercut at the bottom by a final flow. Also, the top of the right picture shows an spot in this cave where the secondary flow began to roof over, in a similar fashion to the creation of the original tube, creating a multi-layered tube. Depending on how you count, this lava tube has between three and seven levels.

These two pictures are from my favorite grotto trip: we rappelled into a lava lake through a gas vent. As the lava in the lake cools, it contracts and cracks (much like the infamous columnar joints,) creating a sunken lake. The left picture shows what may have been the original level of the lake, and a caver perched on its present level – quite the change! The right picture shows how the lake cracked and collapsed as it contracted. This was a great cave!


These are great examples of some important mineral deposits inside lava caves: gypsum, on the left, and calcite, on the right. These form as water drips through cracks in the cave’s roof, eroding it and picking up calcium and carbon. When this reaches the cave, the water evaporates, leaving behind the mineral. The calcite is a type of formation called coralloids, or popcorn.

Caving isn’t all cool rocks, however: sometimes, the rocks really suck. As the pahoehoe flow in the tube begins to cool down, it begins transforming into a’a: this can create a clinker floor, such as the one in the left picture. Most people know that clinkers are kind of lame to walk over, but only after belly-crawling over them do you truly realize just how painful they can be. (I lost two shirts while at the Northwest Caving Association regional in Bend!)

I had a great time this summer, learning first-hand about lava caves, lava fluid dynamics, cave management, and the BLM. The cavers in the area were really a treat, and the caves were fantastic!
I have another post about Idaho's lava tubes here.