Glossary of Terms
Acid Dew also known as condensation corrosion, occurs when warm, outside air enters the cave in the spring and summer. This air mixes with cool, moist air in the cave and becomes saturated with water vapor. When the air meets up with cold rock it condenses as droplets. There is enough dissolved carbon dioxide to form carbonic acid that “eats” at the cave walls. The result are dents the size of water droplets on the cave walls (James 240, Roth 252).
In the Oregon Caves, acid dew can be seen in Watson’s Grotto, occurring mostly in the late spring and early summer. It is caused by warm air from the 110 Exit being dragged or pulled down to the main entrance by the sinking of colder, denser air in the cave. There it condenses on rock still cold from incoming winter air (Roth 252).
References
James, Julia. “Condensation Corrosion.” Encyclopedia of Caves and Karst Science. John Gunn, ed. New York: Fitzroy Dearborn, 2004. 240.
Roth, John. “Interpretive Manual for the Monument’s Showcave”. Cave Junction: Oregon Caves National Monument, 2011.
Argillite is fine-grained metamorphic rock. Originally it was a mudstone (rock created from clays or muds) or a shale. It has undergone a somewhat higher degree of hardening from more interlocking crystals than mudstone or shale, but is less clearly laminated than slate. It is also without shale’s tendency to break along flat surfaces, and lacks the often glossy flat surfaces distinctive of slate (Dietrich, USGS, Bates and Jackson 36).
Argillite is also regarded as a weakly metamorphosed rock, intermediate in character between a claystone and a meta-argillite, in which less than half of the constituent material (clay minerals and micaceous paste) has been reconstituted to combinations of sericite, chlorite, epidote, or green biotite, the particle size ranging from 0.01 to 0.05 mm (Bates and Jackson 36).
Argillite has influenced the cave’s development and has led to the formation of domepits. However, only a few places readily show this rock, most notably in the ceiling of the Connecting Tunnel.
References
Bates, Robert and Julia Jackson, ed. Glossary of Geology. Alexandria: American Geological Institute, 1987.
Dietrich, R.V. "GemRocks: Argillite." Argillite. College of Science and Technology - Central Michigan University, 13 Apr. 2011. Web. 25 Aug. 2011. <http://www.cst.cmich.edu/users/dietr1rv/argillite.htm>.
"Geologic Units Containing Argillite." USGS Mineral Resources On-Line Spatial Data. USGS. Web. 25 Aug. 2011. <http://tin.er.usgs.gov/geology/state/sgmc-lith.php?text=argillite>.
Bedding Planes are the flat surfaces separating the layers that make up sedimentary rocks. They usually mark the end of one deposit and the beginning of another (Tarbuck and Lutgens 689). Bedding planes are originally parallel to the horizon but they can be reoriented by crust altering events (Roth 222).
These zones are often weak and cracking results because different layers respond to stress differently. Imagine pushing over a stack of paper. These cracks, along with faults and joints, are the main way water gets into the marble and forms cave passages (Palmer 78-80; Roth 438). The Dry Room displays a large bedding plane crack.
References
Roth, John. “Interpretive Manual for the Monument’s Showcave”. Cave Junction: Oregon Caves National Monument, 2011.
Palmer, Arthur N. Cave Geology. Dayton, OH: Cave, 2007. 78-80.
Tarbuck, Edward and Frederick Lutgens. “Glossary”. Earth: An Introduction to Physical Geology. Upper Saddle River: Pearson-Prentice Hall, 2005. 688-704.
Bones are all that remain of animals that ventured into the caves and never made it back out. Though no human bones have ever been found in Oregon Caves, a variety of other bones have been uncovered: black bear, grizzly bear, wolf, wolverine, deer, elk, jaguar, bat, salamander, horse, small rodents, and several kinds of birds (Roth 299). A set of black bear bones, about 3,000 years old, are displayed along the trail just before the Exit Tunnel. Remains of a jaguar were found in the Ghost Room. The remains represent the most complete jaguar skeleton found this far north (Roth 39).
Most animals, including humans, typically use caves near the entrance because of the danger of getting lost in deeper parts. It is possible that some of the bones found in the cave are from lost, injured, or sick animals that could not find their way back out. The animals could also have been trapped inside the cave. However, bones can also be deposited in a cave by predators or by water and other gravity-driven flows (landslides, mud flows, etc.). Paleontology—the study of prehistoric life—is used to analyze how and why these bones are found in caves (Andrews and Pinto Leona 561-562).
References
Roth, John. “Interpretive Manual for the Monument’s Showcave”. Cave Junction: Oregon Caves National Monument, 2011. 299.
Andrews, Peter and Ana C. Pinto Leona. “Paleontology: Animal Remains in Caves.” Encyclopedia of Caves and Karst Science. John Gunn, ed. New York: Fitzroy Dearborn, 2004. 561-564.
Boxwork is caused by calcite deposition in cracks. These deposits have larger crystals since the initial cracks had space that permitted growth. Larger crystals are more resistant to erosion so the calcite veins stick out from the ceiling (Bates and Jackson 83). It is considered a speleogen and petromorph because erosion creates it (Roth 460).
Boxwork is found in the Marble Ceiling, Belly of the Whale, and the Souvenir Room.
References
Bates, Robert and Julia Jackson, ed. Glossary of Geology. Alexandria: American Geological Institute, 1987. 83.
Roth, John. “Interpretive Manual for the Monument’s Showcave”. Cave Junction: Oregon Caves National Monument, 2011.
Calcite or calcium carbonate (CaCO3) is a common rock forming mineral. It is a major component of limestone, marble, and the speleothems in the cave. It is a relatively soft mineral, which can be scratched by a fingernail (Bates and Jackson 94).
References
Bates, Robert and Julia Jackson, ed. Glossary of Geology. Alexandria: American Geological Institute, 1987.
Canopy formations are ledges of flowstone extending from a wall (Bates and Jackson 97). Most canopies in Oregon Caves formed on sediment that later washed away. These are known as clastic canopies. A baldacchino canopy is formed when downward growing flowstone meets a water surface, as appears to be the case with a small one in the Petrified Garden (Roth 228).
References
Bates, Robert and Julia Jackson, ed. Glossary of Geology. Alexandria: American Geological Institute, 1987.
Roth, John. “Interpretive Manual for the Monument’s Showcave”. Cave Junction: Oregon Caves National Monument, 2011.
Carbonic Acid (H2CO3) is an acid formed when water absorbs carbon dioxide (Roth 444). Carbonic acid is a relatively weak acid, but given enough time, it can dissolve large quantities of rock. Carbonic acid is the agent responsible for dissolving out most of the world’s caves, including the majority of the passageways in the Oregon Caves (Palmer 408).
References
Palmer, Arthur N. Cave Geology. Dayton, OH: Cave, 2007.
Roth, John. “Interpretive Manual for the Monument’s Showcave”. Cave Junction: Oregon Caves National Monument, 2011.
Cave Bacon is a speleothem that projects from cave walls or ceiling in translucent, thin strips (Bates and Jackson 51). This speleothem, a kind of drapery, contains parallel bands of color that usually are the result of organics but in rare cases may be from iron oxides (Roth 461).
References
Bates, Robert and Julia Jackson, ed. Glossary of Geology. Alexandria: American Geological Institute, 1987.
Roth, John. “Interpretive Manual for the Monument’s Showcave”. Cave Junction: Oregon Caves National Monument, 2011.
Cave Popcorn is a coralloid that looks like small balls, usually made of calcite. This formation grows on cave walls or other speleothems and makes these surfaces rough and abrasive (Palmer 288).
Cave popcorn is formed through a combination of evaporation and loss of carbon dioxide (Roth 25). As cold air enters the cave, especially during winter months, the air is warmed by the cave's consistent 44 degree temperature. Therefore, it is able to evaporate more water. Additionally, since this incoming air has lower carbon dioxide levels compared to the rest of the cave, more carbon dioxide is lost to this air (Roth 56). This results in most cave popcorn being found in windy areas, often by entrances (Palmer 288).
References
Roth, John. “Interpretive Manual for the Monument’s Showcave”. Cave Junction: Oregon Caves National Monument, 2011.
Palmer, Arthur N. Cave Geology. Dayton, OH: Cave, 2007. 288.
Chert is a hard, dense rock made of quartz. It creates irregular beds or nodules in other sedimentary rocks, commonly limestone (Palmer 74). Chert is created out of crystals of quartz that are usually too small to see (Bates and Jackson 114). It is commonly smooth and can vary in color (Palmer 74).
In the Oregon Caves, chert is commonly seen as layers. These were likely formed from the deposition of volcanic ash oozes. In the cave, they can be seen as projecting ledges because chert is more resistant to erosion than marble.
References
Bates, Robert and Julia Jackson, ed. Glossary of Geology. Alexandria: American Geological Institute, 1987.
Palmer, Arthur N. Cave Geology. Dayton, OH: Cave, 2007. Print.
Roth, John. “Interpretive Manual for the Monument’s Showcave”. Cave Junction: Oregon Caves National Monument, 2011.
Columns are speleothems, which occur when a stalactite and a stalagmite grow together (Roth 463). This creates a formation that extends from the ceiling to the floor (Palmer 283).
Columns are found in several rooms, most notably the Grand Column and Miller’s Chapel, but smaller ones are at Niagara Falls, Spiral Stairs, Wind Tunnel (connecting the Grand Column and Miller’s Chapel) and Souvenir Room.
References
Roth, John. “Interpretive Manual for the Monument’s Showcave”. Cave Junction: Oregon Caves National Monument, 2011.
Palmer, Arthur N. Cave Geology. Dayton, OH: Cave, 2007. 283.
Coralloid is a term that encompasses a variety of knobby, globular or coral-like speleothems (Bunnell). These form by splashing water, slow seepage and/or evaporation. Those coralloids not formed underwater have layers of unequal thickness (Roth 464). The most common coralloid is cave popcorn (Bunnell).
References
Bunnell, Dave. "The Virtual Cave: Coralloids." Good Earth Graphics Home Page. 1 May 2005. Web. 20 July 2011. <http://www.goodearthgraphics.com/virtcave/coral/coral.html>.
Roth, John. “Interpretive Manual for the Monument’s Showcave”. Cave Junction: Oregon Caves National Monument, 2011.
Crystals are arrangements of atoms that give minerals their shape (Tarbuck and Lutgens 691). The growth of crystals starts with a clump of molecules that begin as small specks. Often this occurs when contact is made between water and a solid surface. After the initial crystal has formed, more molecule-thick layers attach to create flat surfaces, which are called crystal faces (Murck 34). Usually, crystals vary in size from microscopic to several centimeters long but some can get much longer (Palmer 273).
References
Palmer, Arthur N. Cave Geology. Dayton, OH: Cave, 2007. Print.
Tarbuck, Edward and Frederick Lutgens. “Glossary”. Earth: An Introduction to Physical Geology. Upper Saddle River: Pearson-Prentice Hall, 2005. 688-704.
Dikes are sheet-like intrusions, made of igneous rock, which cut through preexisting structures (Tarbuck and Lutgens 691). Most dikes are a few meters thick and are no more than a few kilometers in length but the largest have lengths of hundreds of kilometers (Tarbuck and Lutgens 163). The dikes seen in the Oregon Caves are small in comparison. The largest cuts across the ceiling in the Ghost Room but other smaller dikes can be found throughout the cave.
References
Tarbuck, Edward J., and Frederick K. Lutgens. Earth: An Introduction to Physical Geology. 8th ed. Upper Saddle River, New Jersey: Pearson, 2005.
Diorite is a coarse-grained igneous rock, intermediate in composition between acidic and basic (Bates and Jackson 185). It is not considered permeable, and this can affect water flow in the Oregon Caves, a fact demonstrated by the location of formations in the Ghost Room. It is made of whitish sodium-rich plagioclase feldspar, dark amphiboles and sometimes dark and thin biotite, which gives it a salt-and-pepper appearance (Tarbuck and Lutgens 121).
References
Bates, Robert and Julia Jackson, ed. Glossary of Geology. Alexandria: American Geological Institute, 1987.
Tarbuck, Edward, and Frederick K. Lutgens. Earth: An Introduction to Physical Geology. 8th ed. Upper Saddle River, New Jersey: Pearson, 2005.
Domepits are also known as shafts. They are vertical cave passages. Most form by acidic, aggressive water flowing into a cave that dissolves the rock. This usually occurs after the cave has drained and at a location where there is a sinkhole or a fracture (Palmer 139; Hess 445).
It is believed that most domepits in the Oregon Caves started to form at the start of deglaciation periods. These were times when glacial and permafrost ice melted, creating more water in the area. Water running off of the non-marble rocks had the maximum ability to dissolve calcite and so bored holes into the marble (Roth 254).
References
Bates, Robert and Julia Jackson, ed. Glossary of Geology. Alexandria: American Geological Institute, 1987.
Palmer, Arthur N. Cave Geology. Dayton, OH: Cave, 2007.
Roth, John. “Interpretive Manual for the Monument’s Showcave”. Cave Junction: Oregon Caves National Monument, 2011.
Draperies are curtain-like, linear flowstone, created from water droplets running down a wall or ceiling. They are often wavy or folded and can have a web-like attachment to stalactites (Roth 230).
References
Roth, John. “Interpretive Manual for the Monument’s Showcave”. Cave Junction: Oregon Caves National Monument, 2011.
Endemics are species or another taxonomic group restricted to a specific geographical region. This is due to geographic isolation or as a response to specific climatic conditions (Allaby 136-137). Endemics can be defined on a variety of geographical and taxonomical scales (Scott 420-421).
References
Allaby, Michael. The Concise Oxford Dictionary of Ecology. Oxford: Oxford UP, 1994. Print.
Scott, Thomas. Concise Encyclopedia Biology. Berlin: Walter De Gruyter, 1996. Print.
Faults are fractures in rock where movement has occurred. They are created by opposing blocks sliding past each other, compressing against each other or pulling apart from each other (Palmer 79). Sudden movement along faults is the reason for most earthquakes. However, most faults are inactive so they show signs of past deformation. Faults vary greatly in size, ranging from a few meters to hundreds of kilometers. (Tarbuck and Lutgens 312-313).
References
Palmer, Arthur N. Cave Geology. Dayton, OH: Cave, 2007.
Tarbuck, Edward J., and Frederick K. Lutgens. Earth: An Introduction to Physical Geology. 8th ed. Upper Saddle River, New Jersey: Pearson, 2005.
Flowstone is a speleothem created by flowing water depositing calcite on the walls or floor (Bates and Jackson 250). The flowstone sampled in the Oregon Caves had a growth rate of about .06 to 1.24 inches per thousand years during the early interglacial periods of the last 500,000 years. There appears to be a growth rate from .3” to .79” per 1,000 years from 13.5 to 9.5 thousand years ago, which shows a faster growth rate in interglacial than glacial periods.
References
Bates, Robert and Julia Jackson, ed. Glossary of Geology. Alexandria: American Geological Institute, 1987.
Ersek, V., H. Cheng, S. W. Hostetler, F. S. Anslow, P. U. Clark, A. C. Mix, and R. L. Edwards. “Environmental Influences on Speleothem Growth in Southwestern Oregon During the last 380,000 years”. Earth and Planetary Science Letters: 2009. 279, 316-325.
Roth, John. “Interpretive Manual for the Monument’s Showcave”. Cave Junction: Oregon Caves National Monument, 2011.
Fluorescence is the emission of light from a mineral when the mineral is exposed to an energy source (Palmer 274). It is a type of luminescence (Bates and Jackson 391).
Fluorescence is produced by calcium salts of fulvic and humic acids derived from soils above the cave. The acids are released by the roots of living plants and by the decomposition of vegetative matter (Shapov 695). These acids are the main source of fluorescence, which can be seen in the presence of certain energy sources, particularly ultraviolet light (“black light”).
White, yellow, pink, red, green, and blue are the most common luminescent colors. The exact color and intensity depends on the mineral type, defects in crystal structure, and the presence of trace elements, as well as the wavelength of the light source (Palmer 274). In the Oregon Caves, fluorescence is best shown at Angel Falls.
References
Bates, Robert and Julia Jackson, ed. Glossary of Geology. Alexandria: American Geological Institute, 1987.
Palmer, Arthur N. Cave Geology. Dayton, OH: Cave, 2007. Print
Shapov, Yavor. “Speleothems: Luminesence.” Encyclopedia of Caves and Karst Science. John Gunn, ed. New York: Fitzroy Dearborn, 2004. 695-696.
Fulvic Acid is an organic substance created in soils (Bates and Jackson 262). It is soluble in acidic and basic solutions and is colored yellow to yellow-brown. It is the main substance that gives cave calcite its fluorescence.
References
Bates, Robert and Julia Jackson, ed. Glossary of Geology. Alexandria: American Geological Institute, 1987.
Graphite is a mineral made up of carbon. It is iron-black to steel-gray, opaque, and greasy to the touch ("Graphite: Graphite Mineral Information and Data."). Graphite can occur as crystals, flakes, scales, grains in veins or bedded masses or diffused in metamorphic rocks. It is used in lead pencils, paints, as a lubricant, and as a monitor in nuclear reactors (Bates and Jackson 287). Graphite makes the dark bands amidst the light-colored calcite in the Oregon Caves marble.
References
Bates, Robert and Julia Jackson, ed. Glossary of Geology. Alexandria: American Geological Institute, 1987.
"Graphite: Graphite Mineral Information and Data." Mineralogy Database - Mineral Collecting, Localities, Mineral Photos and Data. Web. 17 July 2011. <http://www.mindat.org/min-1740.html>.
Helictites are speleothems that appear as distorted cylindrical formations (Palmer 285). This shape is the result of the internal crystal structures, the regular rotation of the crystallographic axis, impurities, wet/dry cycles or a combination of these factors (Roth 231). Helictites have small internal canals approximately 0.01-.05 millimeters in diameter, which supply water to the growing formation. The largest helictites are several meters long; however, most are just a few centimeters in length (Palmer 285). There are few helictites at the Oregon Caves. One can be seen in the Imagination Room and another can be seen in the Beehive Room (in between The Imagination Room and the 110 Exit).
References
Palmer, Arthur N. Cave Geology. Dayton, OH: Cave, 2007.
Roth, John. “Interpretive Manual for the Monument’s Showcave”. Cave Junction: Oregon Caves National Monument, 2011.
Humic Acid is an organic compound extracted from humus found in soil, low-rank coals and aquatic environments. It forms by a gradual accumulation of residue left by microorganisms (Encyclopedia Britannica), is black, acidic, and insoluble in other acids and organic solvents. Humic acid is not a single acid but rather a complex mixture of a variety of acids (Bates and Jackson 315).
References
Bates, Robert and Julia Jackson, ed. Glossary of Geology. Alexandria: American Geological Institute, 1987.
"Humic Acid" Encyclopedia Britannica. Encyclopedia Britannica Online Academic Edition. Encyclopedia Britannica, 2011. Web. 29 Jul. 2011. <http://www.britannica.com/EBchecked/topic/276207/humic-acid>
Ice Wedging is the freeze-thaw action of water that breaks up rock. As cold winter air enters the cave, it freezes the water in the formations. Since water expands when it freezes, it puts pressure on the formations, which can cause them to break or crack. Although breakage may not occur after just one freeze-thaw cycle, each one works to further weaken the rock (White 60).
References
White, Elizabeth. “Breakdown.” Encyclopedia of Caves. David Culver and William White, ed. Burlington: Elsevier Academic Press, 2005. 60.
Igneous rocks are formed from the cooling and solidification of molten rock, which forms in the Earth’s upper mantle (Tarbuck and Lutgens 27). The word "igneous" comes from the Latin meaning "of fire, fiery."
Molten rock is hot enough to be a viscous liquid. High temperatures in the upper mantle are the result of a number of factors, including higher pressure and friction between moving tectonic plates. When molten rock is under the ground it is called magma. Lava is molten rock that is above the ground.
When magma cools under the ground, the result is referred to as a plutonic rock. When lava cools above the ground, the resulting rocks are known as volcanic rocks (Murck 42).
References
Murck, Barbara W. Geology: A Self-Teaching Guide. New York, New York: John Wiley & Sons, 2001. Print.
Tarbuck, Edward J., and Frederick K. Lutgens. Earth: An Introduction to Physical Geology. 8th ed. Upper Saddle River, New Jersey: Pearson, 2005. Print.
Iron oxides are chemical compounds made of iron and oxygen that cause rusting on metals (Tanner). Hematite (Fe2O3) and Magnetite (Fe3O4) are minerals of iron oxide (Idaho State University).
References
"Glossary Database." Idaho Museum of Natural History | Idaho State University. Web. 29 July 2011. <http://imnh.isu.edu/>.
Tanner, Arnold O. "USGS Minerals Information: Iron Oxide Pigments." USGS Mineral Resources Program. USGS, 26 May 2011. Web. 29 July 2011. <http://minerals.usgs.gov/minerals/pubs/commodity/iron_oxide/>.
Joints are parallel fractures in bedrock where no significant movement has taken place. They usually are perpendicular to the bedding but some joints can cut diagonally across the beds. They funnel water and are needed for early cave development especially in shallow parts of caves (Palmer 78).
References
Palmer, Arthur N. Cave Geology. Dayton, OH: Cave, 2007. 78-80.
Karst is a type of topography characterized by sinkholes, caves, and underground drainage. It is formed on limestone, gypsum, and at times other types of rock such as marble, by erosional processes (Bates and Jackson 356). Karst topography describes what an area looks like if soluble rocks and water are both present for long periods of time.
References
Bates, Robert and Julia Jackson, ed. Glossary of Geology. Alexandria: American Geological Institute, 1987.
Limestone is a sedimentary rock composed of mostly calcium carbonate usually in the form of calcite. It is formed either by organic or inorganic processes and includes chalk (microscopic animals), calcarenite (sand-sized particles), coquina (shells cemented together), and travertine (usually formed in springs with lots of plant matter) (Bates and Jackson 379).
References
Bates, Robert and Julia Jackson, ed. Glossary of Geology. Alexandria: American Geological Institute, 1987. 379.
Loess is non-stratified deposit of silt, clay or dust that has been re-deposited by wind (Roth 473). It tends to form thick, uniform deposits (Murck 161).
In the Oregon Caves, it was re-worked and deposited by water, which can be seen at the bottom of the stairs going to Paradise Lost.
References
Murck, Barbara W. Geology: A Self-Teaching Guide. New York, New York: John Wiley & Sons, 2001. 161.
Roth, John. “Interpretive Manual for the Monument’s Showcave”. Cave Junction: Oregon Caves National Monument, 2011. 473.
Marble is a metamorphic rock made up of recrystallized calcite, dolomite, or both (Bates and Jackson 401). It is created from the metamorphism of a sedimentary carbonate rock such as limestone or dolomite rock (Roth).
References
Bates, Robert and Julia Jackson, ed. Glossary of Geology. Alexandria: American Geological Institute, 1987.
Roth, John. “Interpretive Manual for the Monument’s Showcave”. Cave Junction: Oregon Caves National Monument, 2011.
Metabasalt is a low-grade, metavolcanic rock that is rich in magnesium and iron and has preserved evidence of its original basaltic character (USGS).
Basalt is the general name for dark-colored, igneous rocks, commonly forming near the surface. It is composed chiefly of the minerals plagioclase and pyroxene (Bates and Jackson 37).
Once basalt has undergone high levels of heat and pressure it will become a meta-basalt.
References
Bates, Robert and Julia Jackson, ed. Glossary of Geology. Alexandria: American Geological Institute, 1987.
“Geological Units Containing Meta-basalt.” USGS Mineral Resources On-Line Spatial Data. United States Geological Society, 21 Dec. 2010. Web. 31 July 31, 2011. http://tin.er.usgs.gov/geology/state/sgmclith.php?text=meta-basalt.
In geology, the word metamorphic refers to a rock family whose original form has been altered by heat, pressure or both (Murck 42). Metamorphic rocks are created from existing igneous, sedimentary or even other metamorphic rocks. The existing rock that is metamorphosed, or altered by heat and/or pressure, is referred to as a parent rock (Tarbuck and Lutgens 29). The most common metamorphic rock in the Oregon Caves is marble.
References
Murck, Barbara W. Geology: A Self-Teaching Guide. New York, New York: John Wiley & Sons, 2001. Print.
Tarbuck, Edward J., and Frederick K. Lutgens. Earth: An Introduction to Physical Geology. 8th ed. Upper Saddle River, New Jersey: Pearson, 2005. Print.
Moonmilk is a white deposit of microscopic crystals, usually calcite. It is composed of small flat crystals that look plate-like. These crystals are loosely packed together and act like a sponge, which allows for the deposit of large amounts of water. They are typically pasty when wet and powdery when dry (Palmer 298).
The conditions necessary to form calcite moonmilk are not well understood. Microbial activity is widely considered a requirement, but it is possibly not a necessary condition. Calcite moonmilk can form by direct precipitation from solution, by replacement of earlier minerals, or by carbonate weathering. These can all form with or without microbial influence. Some moonmilk has the form of pool deposits, dripstone, or flowstone and may result from replacement or alteration of earlier calcite formations (Palmer 298).
Moonmilk frequently contains bacterial or fungal species that produce antibiotics. A study by Rogue Community College in 1996 showed that some of the Oregon Caves’ moonmilk does contain the genus Penicillium.
References
Palmer, Arthur N. Cave Geology. Dayton, OH: Cave, 2007. 298.
Roth, John. “Interpretive Manual for the Monument’s Showcave”. Cave Junction: Oregon Caves National Monument, 2011. 22.
Pendants are speleogens projecting from a ceiling. They are the erosional remnants of bedrock, created when softer, less resistant rock is eroded away. Pendants are usually 10 to 100 cm diameter (Lundberg 318) and they tend to be more than three times longer than they are thick (Roth).
References
Lundberg, Joyce. “Karren.” Encyclopedia of Caves. David Culver and William White, ed. Burlington: Elsevier Academic Press, 2005. 315-321.
Roth, John. “Interpretive Manual for the Monument’s Showcave”. Cave Junction: Oregon Caves National Monument, 2011.
A Petromorph is a cave formation that, because of differential solution, projects from more dissolved parts of the bedrock. Examples of this formation include boxwork, arches, quartz veins, dikes (when they stick out), and ledges of chert or argillite. Pendants that form mostly due to more insoluble material like chert or argillite can be considered petromorphs but they are rare in Oregon Caves due to the structural weakness of the argillite and fractured and discontinuous chert layers (Roth 250, 256, 476).
References
Roth, John. “Interpretive Manual for the Monument’s Showcave”. Cave Junction: Oregon Caves National Monument, 2011.
Radiometric dating calculates age for materials, such as rocks and minerals, by measuring the presence of short-term radioactive isotopes, the "parent," relative to the isotope's byproduct, the "daughter" (Bates and Jackson 548, Palmer 412). Short-term radioactive isotopes decay from "parent" isotopes to "daughter" isotopes. The rate of decay from "parent" to "daughter" is also known as the isotope's half-life. This proves useful, since the half-life of many isotopes have been measured, and this rate of decay is known to be constant. So, based on the number of half-lives, determined by the proportion of "daughter" isotopes to "parent" isotopes present in the material, the amount of time that the isotope has been decaying can be determined.
Although, there are many radiometric isotopes in existence, only six are useful for determining age. These include rubidium-87, thorium-232, potassium-40, carbon-14, and two isotopes of uranium (Tarbuck and Lutgens 284-287). Only the uranium isotope, which breaks down into thorium, and carbon-14, which breaks down into a stable carbon isotope, have been used for determining ages inside Oregon Caves. Carbon-14 is also known as radiocarbon.
References
Bates, Robert and Julia Jackson, ed. Glossary of Geology. Alexandria: American Geological Institute, 1987. Print.
Palmer, Arthur N. Cave Geology. Dayton, OH: Cave, 2007. Print.
Tarbuck, Edward J., and Frederick K. Lutgens. Earth: An Introduction to Physical Geology. 8th ed. Upper Saddle River, New Jersey: Pearson, 2005. Print.
Rillenkarren are downslope solution grooves about one centimeter wide, with sharp intergroove crests (Bates and Jackson 569). Rillenkarren can be further defined as narrow solution flutes that are closely packed and consisting of straight grooves separated by sharp parallel ribs that are initiated at the rock edges and disappear downwards. Rillenkarren are remarkable for the regularity of the herringbone pattern that they form on the top of rocks and by their individual linear rills, parabolic in cross section and up to 60 cm long, and whose shape is constant along their whole length (Gines 470).
References
Bates, Robert and Julia Jackson, ed. Glossary of Geology. Alexandria: American Geological Institute, 1987.
Gines, Angel. “Karren.” Encyclopedia of Caves and Karst Science. John Gunn, ed. New York: Fitzroy Dearborn, 2004. 470-473.
Rimstone Dams, also known as gours, are deposits of calcite that form around the edges of cave pools or streams. Crystallization is most rapid where the water flows over the edges of the rimstone, because the carbon dioxide loss is greatest there. The pools deepen as the rimstone grows upward. Rimstone dams on steep slopes tend to be taller and less sinuous than those on gentle slopes. Dam tops are horizontal and range in height from less than a centimeter to several meters. Their spillover surfaces usually consist of rough-textured calcite that slopes away from the pool in the downstream direction, although rimstone formed by small trickles can have vertical or even slightly overhanging outer walls (Palmer 277-278).
The inner sides of a dam beneath the pool surface are usually lined with coralloid or shrub-like calcite growths. Rimstone dams can also form in stream beds or on the slopes of large flowstone mounds. When a cave becomes air filled, its streams begin to lose much of their carbon dioxide by air exchange through open entrances, so that calcite may precipitate rather than dissolve (Palmer 277-278).
References
Palmer, Arthur N. Cave Geology. Dayton, OH: Cave, 2007. Print
The River Styx is an underground stream that is characteristic of karst geology. Underground streams start at the surface and eventually disappear below the ground to form sinking streams. The River Styx begins as Cave Creek above the cave, flows further downhill until eventually the stream makes its way underground and into the cave through a bed of sediment. Once in the cave, the stream is renamed the River Styx (Palmer 30).
The River Styx can be seen in several of the rooms in the cave, notably near Watson’s Grotto, the Marble Ceiling, the Belly of the Whale, and before the Connecting Tunnel. The River Styx has carbonic acid from the carbon dioxide picked up from bacteria and plant remains above the cave. The River Styx has served a role in eroding many of the passages and rooms of the Oregon Caves.
The River Styx is the site of several studies in the cave, such as the erosive power of the stream, its water chemistry, its height throughout the year, as well as dye tests for the length of time the water takes to reach the cave. Once the stream courses past Watson’s Grotto, it emerges outside once again as Cave Creek.
References
Palmer, Arthur N. Cave Geology. Dayton, OH: Cave, 2007. Print
Scallops are small shallow intersecting hollows formed on the surface of soluble rock by turbulent water (Bates and Jackson 589-590). Scallops indicate both the direction and the velocity of the water that formed them. They are especially useful in determining former flow conditions in passages that are now dry. Scallops range in length from about half a centimeter to one or two meters (Palmer 147).
The flow direction of the most recent water to enlarge the cave is shown by the scallop asymmetry. The steep sides of the hollows are on the upstream side. The faster the flow, the smaller the scallops (Palmer 147).
Scallops are very sensitive to local flow conditions and are not formed if the water velocity is less than about 1cm/sec, because the turbulent eddies are not stable enough in such slow-moving water. At velocities greater than about 3 m/sec the bedrock surfaces are usually abraded by sediment, which prevents scallops from forming (Palmer 147-148).
References
Bates, Robert and Julia Jackson, ed. Glossary of Geology. Alexandria: American Geological Institute, 1987.
Palmer, Arthur N. Cave Geology. Dayton, OH: Cave, 2007. Print
Sediment is unconsolidated material created by weathering. It can be transported by water, wind, or ice, and then deposited (Tarbuck and Lutgens 700).
SEE ALSO: Sedimentary Rocks
References
Tarbuck, Edward J., and Frederick K. Lutgens. Earth: An Introduction to Physical Geology. 8th ed. Upper Saddle River, New Jersey: Pearson, 2005. Print.
Sedimentary Rocks are composed of sediment (Murck 42). Sediments are turned into rock by one of two processes: compaction or cementation.
Compaction occurs when the weight of the overlying materials forces sediment into a dense mass.
Cementation takes place when water, which contains dissolved substances, percolates out of the open spaces between sediments. With time, materials dissolved in water precipitate onto the grains. As they grow, they interlock and cement the sediment into a solid mass (Tarbuck and Lutgens 28).
References
Murck, Barbara W. Geology: A Self-Teaching Guide. New York, New York: John Wiley & Sons, 2001. 42.
Tarbuck, Edward J., and Frederick K. Lutgens. Earth: An Introduction to Physical Geology. 8th ed. Upper Saddle River, New Jersey: Pearson, 2005. 28.
A sinkhole is a surface depression formed by dissolution of bedrock or by collapse of an underlying cave (and often a combination of both) (Palmer 413).
Sinkholes commonly form in two ways. Some develop gradually over many years without any physical disturbance of the rock. In these situations, the carbonate rock immediately below the soil is dissolved by downward-seeping rainwater that is freshly charged with carbon dioxide. With time the bedrock surface is lowered and the fractures in which the water seeps are enlarged. As the fractures grow in size, soil subsides into the widening voids, from which it is removed by groundwater flowing in the passages below. These depressions are usually shallow and have gentle slopes (Tarbuck and Lutgens 525).
By contrast, sinkholes can also form abruptly and without warning when the roof of a cavern collapses under its own weight. Typically, the depressions created in this manner are steep-sided and deep (Tarbuck and Lutgens 525). This likely is what occurred at the 110 Exit.
References
Palmer, Arthur N. Cave Geology. Dayton, OH: Cave, 2007. Print
Tarbuck, Edward J. and Lutgens, Frederick K. Earth An Introduction to Physical Geology. Upper Saddle River, N.J, 1993.
Soda Straws are stalactites that are tubular and, at least initially, are hollow. The outer diameter of a soda straw varies from 5 to 10mm and the inner diameter ranges from 2 to 6 mm (Frisia 570-571). Most grow from 1/10” to 1” per thousand years and the longest in the cave is said to be 14”. However, the longest in the nation is 21’2” in Kartchner's Cave and the theoretical limit is 26” before their own weight would make them fall (Roth 32).
References
Frisia, Silvia. “Stalactites and Stalagmites.” Encyclopedia of Caves. David Culver and William White, ed. Burlington: Elsevier Academic Press, 2005. 570-571.
Roth, John. “Interpretive Manual for the Monument’s Showcave”. Cave Junction: Oregon Caves National Monument, 2011. 32.
Speleogens are erosional features in a cave (Culver and White 628). They are shapes in space in which the original rocks were dissolved or broken away. Speleogen features include: scallops, pendants, boxwork, domepits and even the cave itself could be considered a large speleogen (Roth 191).
References
Culver, David and William White Herman, Janet. “Glossary.” Encyclopedia of Caves. ed. Burlington: Elsevier Academic Press, 2005. 628.
Roth, John. “Interpretive Manual for the Monument’s Showcave”. Cave Junction: Oregon Caves National Monument, 2011.
Speleothems are secondary deposits in a cave, since they only form after there is an established passage and entrance. This is because speleothems, or cave formations, need open space and air to grow (Bates and Jackson 632). Formations are created by water entering a cave passage, which allows carbon dioxide to escape to the air. This action results in water no longer being able to hold onto calcite. It forces calcite to be deposited, which allows for the establishment of the formations. There are various types of formations, all made out of calcite, but they look very different. The shape of any speleothem is determined by the speed and direction of the waterflow while the calcite is being deposited (Dreybrodt 543-548).
Speleothem formations in the cave include: stalactites, stalagmites, soda straws, flowstone, cave popcorn and drapery.
Some of the speleothem formations in the Oregon Caves have been dated using radiometric dating, using isotopes of uranium and thorium. The oldest flowstone was found to be 330,000 years old. However, in some of the oldest cave layers there is not enough uranium to use for dating, so a different method using oxygen and carbon isotopes is used. By comparing the ratios between oxygen and carbon isotopes with ocean sediment layers, the oldest known speleothem has been found to be 516,000 years old (Roth 389).
References
Bates, Robert and Julia Jackson, ed. Glossary of Geology. Alexandria: American Geological Institute, 1987.
Culver, David and William White Herman, Janet. “Glossary.” Encyclopedia of Caves. ed. Burlington: Elsevier Academic Press, 2005. 628.
Dreybrodt, Wolfgang. “Speleothem Deposition.” Encyclopedia of Caves. David Culver and William White, ed. Burlington: Elsevier Academic Press, 2005. 543-548.
Stalactites are speleothems that are cylindrical deposits on the ceiling of the cave (Bates and Jackson 640). They form from calcite deposition from water. When water saturated with calcite drips slowly enough from the ceiling, calcite has time to be deposited (Roth 63).
References
Bates, Robert and Julia Jackson, ed. Glossary of Geology. Alexandria: American Geological Institute, 1987.
Roth, John. “Interpretive Manual for the Monument’s Showcave”. Cave Junction: Oregon Caves National Monument, 2011.
Vermiculations are sediment deposits, usually formed of clay or silt. They appear in worm-like, parallel, or polygonal patterns. Vermiculations tend to be a couple of millimeters wide, a millimeter thick and a few centimeters long (Palmer 159-160). A colloquial name for them is clay worms.
Vermiculations commonly form on smooth, damp surfaces, where there is an accompanying wetting and drying cycle and perhaps a microbial process (Roth 32). The clay usually accumulates from air-borne dust, but can also be brought in during flooding events (Palmer 159-160). Since clay has a slight electrical charge, the sediment particles become attracted to one another as rooms drain and dry out following a flooding event (Bini, Gori, and Gori; Roth 32-33). Vermiculations are most common in the Oregon Caves where muddy floodwater from melting glaciers filled the room (Roth 484).
References
Palmer, Arthur N. Cave Geology. Dayton, OH: Cave, 2007. 159-160.
Roth, John. “Interpretive Manual for the Monument’s Showcave”. Cave Junction: Oregon Caves National Monument, 2011. 32, 484.
Bini, Alfredo, Cavalli Gori and Silvio Gori. “A Critical Review of Hypotheses on the Origin of Vermiculations”. International Journal of Speleology, v.10: 1, 1978.