Geological Features of Howe’s Cavern
The walls of Howe Caverns consist of two types of limestone (Coeymans and Manlius) from different periods in the Earth’s early history, as well as a rock known as Rondout waterred.
The Manlius limestone is seen most clearly and is the most abundant, while Coeymans limestone can be seen in the upper portion of the cave near the entrance. Coeymans limestone is more difficult to dissolve than the Manlius variety, so the water naturally chose a lower path through the Manlius layer. As a result, almost perfectly flat ceilings can be seen in parts of the cavern, which are actually the underside of the Coeymans limestone layer. Rondout waterred is the cream-colored rock that runs along the underground stream.
Scientists believe all of these rock layers were laid down by the ancient, extinct sea during the Silurian and Devonian periods of our Earth’s formation. They are all sedimentary rock, formed by layers of deposits which settle out of a body of water and are then compressed into solid rock. To give you an idea of the age of these rocks, scientists estimate the Silurian Age began about 435 million years ago and ended when the Devonian Age began around 395 million years ago.
While there are a few fossils visible in the cavern walls, the main fossil beds lie in the layers of limestone above the cavern ceiling. This means the rock from which Howe Caverns is carved is older than most fossils. But the building process in Howe Caverns is never done! Nature is still hard at work in the great cave – as proven by the fact that we still hear, see and feel the droplets of water falling – and the cavern’s face is always changing. It changes so slowly that the smudges left by smoking torches nearly a century ago can still be seen on the glowing flowstone walls today.
Once the ancient subterranean stream cut its path through the limestone layers, marvelous formations named stalactites, stalagmites and flowstone began to form. These unique stone formations grow at an unbelievably slow rate: only about one cubic inch (about the size of a small ring box) will form in 100 years.
Howe Caverns lie in Coeymans limestone and Manlius limestone. Coeymans limestone can be seen in the upper portion of the cave near the entrance. Coeymans limestone is more difficult to dissolve than the Manlius variety, so the water naturally chooses a lower path through the Manlius layer. As a result, almost perfectly flat ceilings can be seen in parts of the cavern, which are actually the underside of the Coeymans limestone layer. Rondout waterlime is the cream-colored rock that runs along the underground stream.
When rainwater seeps down through the soil above, it picks up a very, very small amount of limestone as it travels. In fact, there is only about a teaspoon of limestone dissolved in every gallon of rainwater that filters through the surface above the caverns. As this rainwater drips slowly through the cave’s roof, the droplets of water evaporate, leaving behind tiny amounts of limestone on the cavern ceiling. In this way, stalactites grow downward from the vaulted cavern roof, particle by particle, over the course of millions of years.
The stone formations which grow up from the cavern floor are created in the same manner. Sometimes large droplets of water filtering through the cave roof don’t have time to evaporate before they roll down a stalactite and drip off to the cave floor below. That’s why stalagmites usually form directly below stalactites and continue to grow as more droplets fall from above. In some cases (such as the grand Pipe Organ formation at Howe Caverns), stalactites and stalagmites will actually grow together to form columns. (By the way, it’s easy to remember the difference between stalactites and stalagmites. The word “stalactites” contains the letter “c” – like the word “ceiling.” “Stalagmite” uses the letter “g” and so does the word “ground.” Stalactites grow from cavern ceilings, while stalagmites grow upward from the ground!)
Flowstone is formed in much the same way as stalactites and stalagmites, except the water flows down the cavern walls. This wonderful rock formation resembles sheets of frozen, rippling ice. Other minerals in the water that carry the limestone give flowstone, stalactites and stalagmites their lovely colors. With the exception of the colors created by lights in the cavern, all of the colors you see at Howe Caverns are completely natural.
Rust-colored formations are caused by the presence of iron in the dripping water… green is from waterborne copper… grey indicates the presence of aluminum oxide… yellow comes from sulphur… and pure calcite makes lovely, milky-white formations.
Calcite Crystal Deposits
Features such as stalagmites are technically called Speleothems. The word “Speleothem” is derived from the Greek words “spelaion” (cave) and “thema” (deposit). The process by which Speleothems are formed is the reverse of that by which limestone is dissolved to produce caves.
Speleothems consist mainly of calcite, the same mineral that makes up limestone, in its crystallized form.
Conditions are right for the process to begin when the water table lowers and air enters the cave. Calcite is dissolved from the limestone above the cave by slightly acidic water as it percolates downward through the soil.
In the soil, where plant and animal remains are decaying, the carbon dioxide content is about 300 times that of the outside atmosphere. The carbon dioxide combines with the water and produces carbonic acid, which in turn dissolves some of the limestone it passes through as it moves downward toward the cave. When the acidic water reaches the cave, the carbon dioxide is released and calcite is precipitated (redeposited) on cave walls, ceilings and floors.
Speleothems form at varying rates as calcite crystals build up, one upon the other. Several factors can determine the rate of growth. Two important factors are the temperature outside, which affects the rate plants and animals decay(amount of carbon dioxide in the soil), and the amount of rainfall. The shape of Speleothems is determined by how the acidic water enters the cave (by dripping, seeping or splashing) and how the water stands or flows after entering the cave. Stalactites are the most common Speleothems.
Please note: This is an excerpt from the Cave and Karst Curriculum and Resource Guide.
A Non-renewable Resource
Great care must be taken to protect and preserve these great underground wonders. Caves are non-renewable natural resources which benefit and enrich our lives in many ways, a few of which are:
Insect Control, Scientific Knowledge, Water Supply and Education/Recreation. Caves may seem eternal, having been around for hundreds of thousands or even millions of years. However, every cave is sensitive, whether open to the public as a show cave or an undeveloped wild cave. The biggest threat to these fragile environments is man. This threat includes, but is not limited to, Vandalism, Quarrying, Dam Construction and Water Pollution.
Caves and the land in which they are located are closely tied together. What happens on the surface can affect the subsurface, including groundwater and caves. For many years it was generally believed soil protected groundwater from contamination by human activities on the surface, filtering out the contaminants. However, this was found to be untrue. Activities on the land’s surface – including sewage pollution, solid waste pollution, oil and gas pollution, and runoff from agricultural chemicals can adversely affect the quality of groundwater, which is the drinking water for about 50% of the US population.
Due to its complex geological history, New York has four types of aquifers. Those in carbonate rock are located in the valleys of central and southeastern NY. In the caves, solution channels and sinkholes (karst terrain) of these aquifers can store large amounts of groundwater. Contaminants from the surface can move rather quickly and reappear in water supplies miles from their source.
Touring a cavern gives us a good picture of karst. Imagine you are actually inside the groundwater system, touring a portion of an aquifer, where all the cracks and crevices were once completely filled with water. As the limestone beneath the soil was dissolved to form the cave, the overlying soil settled or collapsed to form sinkholes. Water entering the ground through sinkholes can carry soil, organic debris, and pollutants. This surface water becomes part of the groundwater flow system.
Contaminated water draining through a sinkhole in turn pollutes groundwater that wells and springs draw from. Sinkholes are environmentally sensitive areas and should never be used as dump sites. Sinkholes which have been used as dumps should be cleaned out to prevent any further contamination of the groundwater. Treat sinkholes with care. Remember: what you see in a sinkhole is what you may get from your faucet.
Detecting groundwater contamination can be difficult, much more difficult than detection of surface water contamination. Because we can’t see groundwater, we don’t usually notice any contamination until it appears in water from springs or wells. Cleaning up groundwater can be costly and difficult.
The public needs to understand that surface wastes can easily enter the groundwater system in karst areas. Factories which produce industrial and hazardous wastes must be located in areas away from sinkholes. Newer fuel storage tanks, which are less likely to leak, should be used and older storage tanks replaced. Old city sewage systems need to be repaired or replaced. New plastic pipes will stretch rather than break when new sinkholes develop along sewer lines. Farmers can reduce the use of pesticides and depend more on organic farming methods.
Recycle!! The only way to reduce the amount of trash going to landfills is for all Americans to actively recycle.
Share the message of cave conservation with your family and friends. At any cave you may visit, remember this motto:
Take nothing but pictures; Leave nothing but footprints; Kill nothing but time!!
For more information on cave conservation, visit the American Cave Conservation Association website!
Bats Down Here?
With the exception of a few bats near the natural entrance, moss growing around the electric lights, and bacteria in the underground stream, there is little animal or plant life in Howe Caverns.
However, in many caves the food cycle approaches what is known as a closed ecologic system. In a completely closed system, every organism feeds on and is eventually fed upon by still other organisms within the system. Even though the cave environment shows a higher degree of efficiency than most, cave animals still need help from the outside to survive. All life depends on sunlight even in the darkest areas of a cave. In sunlight, green plants make food. Leaves, twigs and plant debris are carried into the cave by rainwater. Droppings (from animals that go outside the cave to feed then return to the cave to rest, such as bats) add to this organic debris. Inside the cave, bacteria and fungi decompose these materials into simple foods and nutrients.
Fungus-eating creatures such as flatworms, isopods and other small animals within the cave system feed on the molds and bacteria. These animals then become food for the larger predators in the cave, including salamanders, crayfish and blind cave fish. As the larger animals die, decay sets in and organic material is then returned to the cave environment. The entire food chain process begins again. All species in the cave system are dependent upon each other for survival. Remember, the number of animals in a cave is far fewer than their relatives on the surface. For these reasons, we must remember not to disturb life within a cave.
As part of the cave community, we at Howe Caverns are most concerned about the spread of WNS and we’re taking positivie steps to help the national effort to find the cause for this disease which is devastating to these environmentally important creatures. The National Caves Association has formed a WNS Committee and is actively working on educational materials that will be available at Howe Caverns and other member caves.The disease is named for the fuzzy white fungus that grows on sick bats’ noses. The disease has killed more than 1 mlllion bats in the United States.
About WNS White-Nose Syndrome is killing large portions of various bat populations in the United States as they hibernate in caves and mines. Bats are losing their fat reserves that are needed to survive hibernation. This is happening long before winter is over. And, the bats are dying of starvation. While the cause is unknown, WNS gets its name because of the telltale white fungus growing on the noses of infected bats. The fungus, Geomyces destructans, also may appear on the bat’s wings, ears and tail. However, bats affected with WNS do not always have the fungus growing on their bodies. They may, instead, display abnormal behavior such as flying outside during the day in near-freezing weather or not arousing at all after being disturbed. Mortaltiy rates of 70-100% have been documented in the first year in many hibernacula found to have WNS. In caves where fewer than 100% of the bats died the first year, populations continue to decline in successive years. Damage to wings and bodies persists in bats that survive a winter in a WNS-infected population.
In 2012 reports of the disease continues to spread across the United States, however, the good news is bat hibernations are seeing more survivors than in previous years. In April 2012 WRGB CBS-6 affiliate in Albany, NY reported from the undeveloped section of Howe Caverns with some encouraging news. CLICK HERE TO WATCH
Bats are an essential, benefical part of the ecosystem. They play critical roles in insect control, plant pollination, seed dissemination and cave ecosystems. They provoide food for other animals (hawks, owls, raccoons, skunks, etc.). Consuming over half their body weight in insects nightly, bats reduce the need for insecticides and are a major predator of night-flying insects. Bats also play a significant role in science and medicine. Bat research has enabled advancements in sonar, vaccine development and blood coagulation, as well as artificial insemination. Decimation of bat populations will cause a substantial ecological ripple effect, with far-reaching consequences.
More information is available at the websites of Bat Conservation International at www.batcon.org and the National Speleological Society at www.caves.org/WNS