This is a strenuous hike. There are many open pit mines along the way to check out, but do be careful. Area is only open from sunrise to sunset. Take a snack with you and plenty of water. A bright flashlight is also highly recommended.
Local geology
Imagine a landscape marked by limestone and dolomite ridges, dry hollows, caves, sinkholes, big springs, natural bridges, and streams that sink into their own beds.That's Missouri.
Missouri is well known as The Cave State because of its large number of caves. At least 180 cave’s in Barry County alone and over 5,700 Statewide. Certainly the caves here are among the largest and most spectacular in the nation. There are caves in 78 of our 114 counties, mostly in the Ozarks, but some as far north as Hannibal.
Many of these ancient caves have passed through several lifetimes of development, starting with the dissolving action of slightly acidic groundwater on fractured bedrock. This natural plumbing enlarged because of collapse, canyon cutting by internal streams, accumulation of clays and gravels and re-excavation by streams. Drippings of flowing water laden with dissolved rock deposited calcite in these openings. The eventual fate of a cave is to erode away, as illustrated by local natural bridges.
A sinkhole is a depressed area usually formed by solution of surficial bedrock or collapse of underlying caves. The surface expression of a sinkhole is typically a conical depression or area of internal drainage. Sinkholes range in size from several square yards to hundreds of acres. They may be quite shallow or may extend hundreds of feet deep. Sinkholes are places where there is rapid recharge (replenishing) of groundwater from the surface and, therefore, are areas of potential groundwater contamination. For this reason, managing surface water and waste disposal in sinkhole-prone areas are important to maintaining good groundwater quality.
These events ranged over huge spans of time. The sea deposited Missouri's oldest cavernous rocks around 500 million years ago during the Cambrian Period.
The Gasconade Dolomite of the Ordovician Period (around 450 million years old) is the most cavernous rock formation in Missouri.
In the Mississippian Period (about 350 million years ago), marine organisms created the Burlington/Keokuk Limestones which today are highly cavernous around Springfield, Columbia and northeastern Missouri. By the time the Cenozoic Era began 66 million years ago, Missouri had dolomite and limestone up to 1500 feet thick. At present, karst's are developing rapidly, as evidenced by our large, deep springs and numerous losing streams.
The Springfield Plateau contains hundreds of relatively younger caves. Expanding urban areas threaten groundwater and the endangered Ozark cavefish. Some caves have beautiful speleothems (i.e. stalactites), despite all the mud, and cave structures tend to be fairly simple.
The largest continuous karst terrain is in south-central Missouri. The Salem Plateau is considered a cave factory, with the oldest and most spectacular caves in the Gasconade and Eminence dolomites. Some caves may have paleocave components dating back many millions of years. The caves are wet and muddy with lots of "unctuous red clay," that is a sticky, slimy clay with no grit. This stuff completely stains cavers coveralls and gear.
The Ozark Plateau
A Physiographic Region is a region of which all parts are similar in geologic structure and climate and which has consequently had a unified geomorphic history; a region whose patterns of relief features or landforms differs significantly from that of adjacent regions. The Ozark Plateau physiographic is a physiographic and geologic highland region of the central United States. It covers much of the southern half of Missouri and an extensive portion of northwestern and north central Arkansas. This whole area is actually not mountains but what’s called a dissected plateau.
Although sometimes referred to as the Ozark Mountains, the region is actually a high and deeply dissected plateau. Geologically, it is a broad dome around the Saint Francois Mountains. The Ozark Highlands area, covering between 47,000 square miles and 50,000 square miles depending upon the source, is by far the most extensive mountainous region located between the Appalachians and the Rocky Mountains. Together, the Ozarks and Ouachita Mountains form an area known as the U.S. Interior Highlands, and are sometimes referred to collectively. For example, the ecoregion called Ozark Mountain Forests includes the Ouachita Mountains. The Arkansas River valley and the Ouachitas, both south of the Boston Mountains, are usually considered not part of the Ozarks.
Set apart by rugged terrain, the Ozarks form a cultural region defined largely by a population that professes political conservatism, religious conservatism and sectarianism, and a strong belief in the values of rural living.
Located in the south-central United States, the Ozarks are a heavily forested group of highlands. They extend southwestward from St. Louis, Missouri, to the Arkansas River. Along with the adjacent Ouachita Mountains, they represent the largest area of rugged topography between the Appalachians and the Rockies. The region is characterized by many underground streams and springs.
A dissected plateau is a plateau area that has been severely eroded so that the relief is sharp. Such an area may be referred to as mountainous, but dissected plateaus are distinguishable from orogenic mountain belts by the lack of folding, metamorphism, extensive faulting, or magmatic activity that accompanies orogeny. The Ozark Plateau is an example of a dissected plateau formed after regional uplift. These older uplifts have been eroded by creeks and rivers to develop steep relief not immediately distinguishable from mountains.
This whole area is made up of primarily limestone and sandstone with areas of Chert, Mudstone, slate, and Flint just to name a few. Limestone and sandstone are rock types that create caves with ease through erosion and this area is riddled with them.
Karst topography
Karst topography is a geological formation shaped by the dissolution of a layer or layers of soluble bedrock usually carbonate rock such as limestone or dolomite. Subterranean drainage may limit surface water with few to no rivers or lakes. Many karst regions display distinctive surface features, with sinkholes being the most common. However, distinctive karst surface features may be completely absent where the soluble rock is mantled, such as by glacial debris or confined by one or more superimposed non-soluble rock strata. Some karst regions include thousands of caves, although evidence of caves large enough for human exploration is not a required characteristic of karst.
Types and formation
A cave or cavern is a hollow place in the ground, especially natural underground space large enough for a human to enter. Caves form naturally by the weathering of rock and often extend deep underground.
solution caves: Solutional caves are the most frequently occurring caves and such caves form in rock that is soluble, such as limestone, but can also form in other rocks, including chalk, dolomite, marble, salt, and gypsum. Rock is dissolved by natural acid in groundwater that seeps through bedding-planes, faults, joints and so on. Over geological epochs cracks expand to become caves and cave systems.
primary caves: Caves that are formed at the same time as the surrounding rock are called primary caves. Lava tubes are formed through volcanic activity and are the most common primary caves. As lava flows downhill, its surface cools and solidifies. Hot liquid lava continues to flow under that crust, and if most of it flows out, a hollow tube remains. Examples of such caves can be found in the Canary Islands, Jeju-do, the basaltic plains of Eastern Idaho and other places. Kazumura Cave near Hilo, Hawaii is a remarkably long and deep lava tube; it is 65.6 km long (40.8 mi).
How caves form
Cave formation begins when rainwater absorbs carbon dioxide as it falls through the atmosphere. Rain water must have carbon dioxide to become acidic. It must be acidic to chemically react to the limestone bedrock. Rainwater is absorbed by the soil into the ground.
As rainwater comes through the soil it absorbs more carbon dioxide that is being produced by plants that are dead. This changes the ground water to a weaker form of carbonic acid (H2O + CO2 = H2CO3). As it travels down through the ground it comes to solid rock. When the rock is limestone or dolomite caves can form.
The water reacts chemically with limestone and slowly a larger and larger space will form. This happens because the rocks are made of calcium carbonate (CaCO3). This is what you call chemical erosion.
As the space becomes larger and larger the water can flow through. As it flows it erodes. Physical erosion washes away rock and sand. This is what makes a cave larger and forms an underground stream. Finally over hundreds of thousands of years or even millions of years the cave is formed.
Note: Please follow U.S. Fish & Wildlife decontamination protocols after visiting any underground geological site to protect endangered wildlife from deadly diseases such as the WNS fungus.
**Logging requirements**
DO NOT POST ANSWERS IN YOUR LOG.
Send the following answers (to J&LA) via email.
- Add the text, "GC6378R Backwoods Karstology 101: Drippy Hollow" on the first line
- Read the description; fill in the blanks.
a) When did the sea deposit Missouri's oldest cavernous rocks?_____ _____ years ago.
b) Sticky, slimy, no grit soil that stains coveralls is called "_____ _____ clay"
c) A _____ _____ is an area that has been severely eroded so that the relief is sharp. Sometimes confused with mountains.
d) ______ topography is a geological formation shaped by dissolution of soluble bedrock.
- Now visit the posted coordinates. Describe with some detail where the cave mouth is located relative to the trail. (i.e. It's about 3 feet down in a sinkhole.)
- Does this cave have the same relative height throughout, or does the height fluctuate?
- How high is the wall of the pool?
- How tall is the ceiling at the waterfall?
You may send photos of the area to us through the messaging system if you'd like (optional).
After submitting your answers by email, please be creative with your online logs (& generous with your points). Placed with permission.
* Congrats to topgun5403 & Co-Pilot Marty for FTF. We're pleased you enjoyed this adventure!