Cave Formations pt 2: types of formation
Last week, Everyone was asking* “I see all of this accurate and detailed information about the formation of speleothems, but Nathan, where are your sources? All I see is a bunch of crudely drawn illustrations.”
Well! if you don’t like the illustrations, and would love the sources, this is the article for you!!!
Last week, I wrote about about how speleotherms form. (Speleotherms is the fancy way of saying cave formation, like troglodyte is the fancy way to insult a dummy.) For a very quick summary, the answer is: usually, water (or sometimes other fluids,) carry minerals, dropping some along the way, if the minerals collect in a cave, we get a cave formation. If you want the illustrated summary check last week’s blog.
This week I want to write about the different types of speleothems. This is where we run into trouble. We being me, singular. Trouble being problems, plural. Namely. I do not have pictures of every type of cave formation, and I am far too lazy to illustrate them this time. So instead, this week, I provided links, so that you can read about some of these formations and see other people’s pictures.
Mostly, I just wanted an excuse to list all I can, and briefly describe some of the cave formations out there. I’ll break it down into two catagories: formations you can find in Mammoth Cave and formations you have to find elsewhere.
Formations in Mammoth Cave:
Here’s the dissapointing part: Most of Mammoth Cave is light on formations. Water moving swiftly enough to carve deeper and deeper cave passages, but not sticking around long enough to drop minerals off. Much of Mammoth Cave is dry. Meaning lower humidity, and less dripping water. This means that there are vast swaths of Mammoth Cave without most common or popular speleothems. All you get (sarcastic use of all as there is still a lot) is vast enimatic passages, and history carved into the Earth
But if you are in search of speleothems, and you are in Mammoth Cave, you might be in luck!
The good news:
There are Stalactites,(the ones which hang tightly to the ceiling,) and Stalagmites (which push up mightly from the ground,) in several sections of the Cave. Sometimes these lead to their more advanced forms: Columns, when the two meet. Also known as Stalagnates. (after me: Nate… not really, I’ve only used this name abbreviation in Lesotho.)
All of these can be collected under a category called Dripstones. Which means they are formed from dripping water. And they can all be found in sections of Mammoth Cave. There are also locations were several other dripstone offshoots can be found. If you happen to be hungry look out for Cave Popcorn which is what happens when water spills from a lot of pores in the rock together, and forms clusters of formations. And sometimes, the water, which is supposed to drop due to gravity, decides to hang on, and form branching structures with the minerals called Helictites.
If you get too thirsty from the minerally salty cave popcorn, lookout for very delicate, dripstones called soda straws which can sometimes be hollow. However, I’m not sure I’ve seen any of these in Mammoth Cave.
What I have seen in Mammoth Cave are examples of other, related formations, made by the movement of Flowing water. Illogically called: Flowstones- (I can’t think of a reason for this name.) These are deposits that typically form the same way as the above mentioned, but from enough water to be considered a flow. (water moving togther to seeping from—and later allow minerals to collect on the walls, floors and ceilings of a cave. The most famous cave formation in Mammoth Cave, (integral to my upcoming Novel: The Specters of Mammoth Cave) The Frozen Niagara is a massive flowstone. It gets its own category on Wikipedia, but no link or article: stone waterfalls. The flowstones which hang over open air, or form when when water deposits minerals in a line as opposed to a pillar, is called draperies or cave bacon. (more cave food you shouldn’t eat. - it’s all rock.) If water collects in pools, and the sides of these pools collect minerals and grow, then you get Rimstone Dams.
All of these are, typically made of Calcium Carbonate, with other minerals smattered about for color, texture and Flavor. (don’t eat) Look for them, in Mammoth Cave, on various tours. Check out the article below which talks about those and more, and tells you which tours to take in Mammoth Cave. If you can identify them before the ranger, you will impress friends like Bethany Caulfield, and annoy friends like Rudy. (Characters from the upcomming Novel.)
(you can read more at Stalactites, Stalagmites, and Cave Formations - Mammoth Cave National Park (U.S. National Park Service) (nps.gov).)
The Dripstone of Dry Tortugas.
Good news part 2!
Because Mammoth Cave is mostly dry, that means that there are also formations which do not typically occur in wetter, livelier caves.
These include an array of minerals which only form in dry caves, when water carrying soluble minerals evaporates, leaving the minerals behind to make delicate crystalline structures. These are evaporites, or as they are commonly called on tours: Cave Sweat. And include:
Gypsum, a delicate Calcium Sulfate mineral which dissolves in water. It’s usually white, but in Mammoth Cave, it’s often coated in a grey or black surface which is the carbon smoked legacy of past explorers. Gypsum can form delicate flowers, crusts which line the walls like a hard coat, and Snowballs which are spherical globs which often form on cave ceilings. How it grows depends on the environment, and if things get too wet, it can dissolve and fade away.
Mirabilite which forms these fun fibrous crystals, and looks kind of like cotton candy in Mammoth Cave, and Epsomite.
Interestingly, it’s these minerals which probably first brought people into the cave regularly (after curiosity, of course.) As there’s evidence that people have been harvesting Gypsum from the walls and ceilings of Mammoth Cave for thousands of years. Harvesting Gypsum was the industry which brought people into the cave in the early 1800’s as Gypsum was a component of gunpowder, and on the tours where it can still be found, it forms some of the best looking Cave Crystals I have seen.
Check out the above article to learn more.
Now. Are we done? Are those all of the speleothems, or all of the speleothems in Mammoth Cave?
No!
But are we done for today? Yes! Because I want to save some of the crazy cave formations I found for future articles. Some cave formations are made by living organisms. Others are only found deep underground in conditions inhospitable to life. Others are called Moonmilk and need thier own future article.
But, I’ve promised you links, and have a 5K that I need to prepare for. Running for Earth Day!!! So I will leave you with these:
Links for more about Cave Formations!!!!
Speleothem - Wikipedia - this is a great place to start memorizing all of the speleothem names. And find out which cave formations are cool enough to get their own articles.
Speleothems (Cave Formations) - Wind Cave National Park (U.S. National Park Service) (nps.gov) - This is an article about another national park with caves. There are lots of them. If you cant make it to Mammoth Cave, you can still find your way underground.
Mirabilite - an overview | ScienceDirect Topics - here is an article that I almost wrote about in depth. But decided not to because I couldn’t find the time to illustrate the different sulfur containing minerals. I was going to do a parody on the Justice League of S-containing minerals. But if you don’t find enough scientific links, here is a miniature one for you.
More links on their way as we move from the rocks and caves themselves to the people who explored them.
Finally, a picture. So this isn’t all words. I will choose something entirely relevant.
Flowstone in Mammoth Dome. A very important location in the upcoming book The Specters of Mammoth Cave.