All About Flowstone and How Flowstone is Formed

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I love going into different caves, whether on my own or part of a tour, and looking at all of the incredible natural formations. Stalactites, Stalagmites, Cave Bacon, and more! I just had to learn how flowstone is formed!

Just like all the other cave formations, Flowstone is made up of different minerals such as calcite and carbonate minerals! It is just that it is created in a sheetlike manner.

How is Flowstone Formed?

This cave formation is formed when water constantly flows against the walls and floor of the cave. Interestingly, flowstones are not necessarily found in every cave but more so in “solution caves” that mainly consist of limestone.

However, they can be formed in just about any cave once water regularly flows through it and comes in contact with dissolved minerals that lodges on the interior of the cave. This cave formation is a result of the degassing of vadose percolation waters.

Vadose water is subsurface water between the land surface and the saturated zone below the water table. The vadose (or unsaturated) zone includes soil water, which is immediately available to the biosphere.

Whew – what a mouthful!

Flowstone Formation

Interestingly, Flowstone can also be formed on human-made structures such as concrete dwelling when calcium hydroxide is sapped from the concrete, mortar, or lime. Although, those formations that grow outside a cave setting, are known as calthemites.

According to Wikipedia:

Calthemite is a secondary deposit, derived from concrete, lime, mortar or other calcareous material outside the cave environment. Calthemites grow on or under, man-made structures and mimic the shapes and forms of cave speleothems, such as stalactites, stalagmites, flowstone etc.

So, they are associated with concrete degradation as water flows through the cave and along the walls, the calcium carbonate or calcite, gypsum, cave minerals, and aragonite. When the water picks up the mineral as it goes along, as it runs further, it deposits some of the minerals as it no longer has the properties to hold the minerals in the solution. Wherever the water deposits the minerals, it leaves thin layers lined along with each other.

What does it look like? Like a flow of melting wax.

When it comes to flowstone, there are two types…tufa and travertine.

Tufa is created when calcium carbonate is precipitated and leaves a spongy texture.

On the other hand, travertine is formed when calcium carbonate is deposited along the water runs path. It presents a “laminated” texture and usually includes both stalactites and stalagmites. When these thin sheets are formed, it creates imagery in the form of “draperies” or “curtains” and tends to hang from the wall.

While some are translucent, others are formed with brown and beige layers. In general, these layers often have the form and looks of bacon, which is how the name cave bacon comes in.

Understanding Flowstone

Flowstone is among some of the largest speleothems but still has the ability to be damaged even by a single touch. When touched, the human hand’s oil causes the water to change its course and avoid traveling that route again. It will eventually dry out over time.

In addition to the delicate nature of flowstones, they serve a great purpose in understanding when drought was experienced in a particular area. Seeing water is needed to help form flowstone, whenever there is an absence, or the structure is not formed according to how it is usually formed, one can easily tell what the water flow in the region is like. The format flowstone takes, is almost like a waterfall that has frozen in time.

Just about every cave has flowstone, but they do vary in size, shape, and colors. The colors depend on what gets mixed in with the calcite as it forms: clay, iron oxide, dirt, etc. That can make it yellow, brown, red, and so forth. It is simply fascinating to me how nature can present such amazing features without getting any direct help from humans.

Taking a cave tour does not mean you can easily go through areas where there is hanging flowstone as, similar to soda straws, it is rather delicate. Just remember the “leave no trail” principle as you go caving and it will last a long time for others to enjoy.

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