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51-487: The Pärnu is the second longest river in Estonia at 144 kilometres (89 mi), and one of only ten rivers in the country which is longer than 100 kilometres (62 mi). Its catchment area is 6,920 square kilometres (2,670 sq mi), occupying roughly one-sixth of the landmass of Estonia and one of only 15 catchment areas of Estonian rivers which exceeds 1,000 square kilometres (390 sq mi). Its sources are in

102-519: A pioneer of the study of karst in Slovenia and a fellow of the Royal Society , London, introduced the word karst to European scholars in 1689 to describe the phenomenon of underground flows of rivers in his account of Lake Cerknica . Jovan Cvijić greatly advanced the knowledge of karst regions to the point where he became known as the "father of karst geomorphology". Primarily discussing

153-582: A proper noun, the Slovene form Grast was first attested in 1177. Ultimately, the word is of Mediterranean origin. It has also been suggested that the word may derive from the Proto-Indo-European root karra- 'rock'. The name may also be connected to the oronym Kar(u)sádios oros cited by Ptolemy , and perhaps also to Latin Carusardius . Johann Weikhard von Valvasor ,

204-477: A specific location. The strata may contain fossils which aid in determining how old they are and geologist's understanding of sequence and timing. Geologists group together similar lithologies, and call these larger sedimentary sequence formations . There are rules on how formations are named, related to where they are located and what rock type(s) are present. All sedimentary formations shall receive distinctive designations. The most desirable names are binomial,

255-401: A sport than a science and so the underground karst caves and their associated watercourses were, from a scientific perspective, understudied. Karst is most strongly developed in dense carbonate rock , such as limestone, that is thinly bedded and highly fractured . Karst is not typically well developed in chalk , because chalk is highly porous rather than dense, so the flow of groundwater

306-448: A stratigraphic column are essential and are generally keyed to the figure: This recorded information from above will give geologist a description of what rocks are in a cliff or underground. This description allows a better understanding to the entire geology of that area. Can be used to decide whether there is potential for oil or natural gas that exists in these rocks. “The differences between rock unit types and fossils observed within

357-411: A variety of spatial and temporal scales in karst regions, with the purpose of understanding karst aquifers and ecosystems, and the development of the surface and underground structure, so that the environment can be protected and human activities planned effectively. Stratigraphic column A stratigraphic column is a representation used in geology and its subfield of stratigraphy to describe

408-529: A well in a fracture trace or intersection of fracture traces increases the likelihood to encounter good water production. Voids in karst aquifers can be large enough to cause destructive collapse or subsidence of the ground surface that can initiate a catastrophic release of contaminants. Groundwater flow rate in karst aquifers is much more rapid than in porous aquifers. For example, in the Barton Springs Edwards aquifer, dye traces measured

459-505: Is a UNESCO World Heritage Site. Many karst-related terms derive from South Slavic languages , entering scientific vocabulary through early research in the Western Balkan Dinaric Alpine karst. The study of the various aspects of karst regions is called karstology. This includes biological, chemical, ecological, geomorphological, hydrogeological, hydrological, political, socio-economical, and other processes over

510-403: Is a change in the depositional environment. The sedimentary particles are deposited dependent on the net energy in the transportation vector, typically water when dealing with sediments clasts. “Brief descriptions of the units may be lettered to the right of the column, as in the figure, or the column may be accompanied by an explanation consisting of a small box for each lithologic symbol and for

561-562: Is a development of karst observed in geological history and preserved within the rock sequence, effectively a fossil karst. There are for example palaeokarst surfaces exposed within the Clydach Valley Subgroup of the Carboniferous Limestone sequence of South Wales which developed as sub-aerial weathering of recently formed limestones took place during periods of non-deposition within the early part of

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612-538: Is a karst landscape which is developed beneath a cover of insoluble rocks. Typically this will involve a cover of sandstone overlying limestone strata undergoing solution. In the United Kingdom for example extensive doline fields have developed at Cefn yr Ystrad , Mynydd Llangatwg and Mynydd Llangynidr in South Wales across a cover of Twrch Sandstone which overlies concealed Carboniferous Limestone ,

663-515: Is a principle of geology that states that the geologic feature which cuts another is the younger of the two features. It is a relative dating technique used commonly by geologists. There are two main processes that are relevant to sedimentary strata formation: tectonic forces which build mountains and the surface, and erosional processes that transport the sediments to lower energy environments where they are then deposited. These processes results in large piles of accumulated sediments whenever there

714-468: Is developed in areas where salt is undergoing solution underground. It can lead to surface depressions and collapses which present a geo-hazard. Karst areas tend to have unique types of forests. The karst terrain is difficult for humans to traverse, so that their ecosystems are often relatively undisturbed. The soil tends to have a high pH, which encourages growth of unusual species of orchids, palms, mangroves, and other plants. Paleokarst or palaeokarst

765-636: Is frequently unseen until the roof of a cavern suddenly collapses. Such events have swallowed homes, cattle, cars, and farm machinery. In the United States, sudden collapse of such a cavern-sinkhole swallowed part of the collection of the National Corvette Museum in Bowling Green, Kentucky in 2014. The world's largest limestone karst is Australia's Nullarbor Plain . Slovenia has the world's highest risk of sinkholes, while

816-407: Is important in petroleum geology because as much as 50% of the world's hydrocarbon reserves are hosted in carbonate rock , and much of this is found in porous karst systems. The English word karst was borrowed from German Karst in the late 19th century, which entered German usage much earlier, to describe a number of geological, geomorphological, and hydrological features found within

867-399: Is not concentrated along fractures. Karst is also most strongly developed where the water table is relatively low, such as in uplands with entrenched valleys , and where rainfall is moderate to heavy. This contributes to rapid downward movement of groundwater, which promotes dissolution of the bedrock, whereas standing groundwater becomes saturated with carbonate minerals and ceases to dissolve

918-621: Is the following: In very rare conditions, oxidation can play a role. Oxidation played a major role in the formation of ancient Lechuguilla Cave in the US state of New Mexico and is presently active in the Frasassi Caves of Italy. The oxidation of sulfides leading to the formation of sulfuric acid can also be one of the corrosion factors in karst formation. As oxygen (O 2 )-rich surface waters seep into deep anoxic karst systems, they bring oxygen, which reacts with sulfide present in

969-469: The karst upland of Pandivere , in north-eastern Estonia, and its main tributaries join the river from the upland of Sakala. Due to its length, the river Pärnu passes through most of the landscape types found in Estonia. The rivers' surroundings are dominated by agriculture and its upper reaches in Järva County is considered some of the best arable land in Estonia. In the area around Paide town,

1020-636: The range of the Dinaric Alps , stretching from the northeastern corner of Italy above the city of Trieste , across the Balkan peninsula along the coast of the eastern Adriatic to Kosovo and North Macedonia , where the massif of the Šar Mountains begins. The karst zone is at the northwesternmost section, described in early topographical research as a plateau between Italy and Slovenia . Languages preserving this form include Italian : Carso , German : Karst , and Albanian : karsti . In

1071-428: The analysis of the order and position of layers of archaeological remains and the structure of a particular set of strata. The columns can include igneous and metamorphic rocks , however, sedimentary rocks are important geologically because of Classical Laws of Geology and how they relate to the accumulation of sediments and the formation of sedimentary environments. Lithology is a study of bedrock that occurs at

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1122-511: The bedrock. The carbonic acid that causes karst features is formed as rain passes through Earth's atmosphere picking up carbon dioxide (CO 2 ), which readily dissolves in the water. Once the rain reaches the ground, it may pass through soil that provides additional CO 2 produced by soil respiration . Some of the dissolved carbon dioxide reacts with the water to form a weak carbonic acid solution, which dissolves calcium carbonate . The primary reaction sequence in limestone dissolution

1173-450: The complexity of karst aquifers, and need to be supplemented with dye traces , measurement of spring discharges, and analysis of water chemistry. U.S. Geological Survey dye tracing has determined that conventional groundwater models that assume a uniform distribution of porosity are not applicable for karst aquifers. Linear alignment of surface features such as straight stream segments and sinkholes develop along fracture traces . Locating

1224-400: The first part being geographic and the other lithologic. If the rock type is the same, then the formation may be called the "Lyons Sandstone," or the "Benton Shale." When there are several different lithologies within the formation, a more general terminology is used, such as the "Morrison Formation," which contains siltstone, sandstone, and limestone. “For regional studies, geologists will study

1275-557: The fissures. The enlarged fissures allow a larger quantity of water to enter which leads to a progressive enlargement of openings. Abundant small openings store a large quantity of water. The larger openings form a conduit system that drains the aquifer to springs. Characterization of karst aquifers requires field exploration to locate sinkholes, swallets , sinking streams , and springs in addition to studying geologic maps . Conventional hydrogeologic methods such as aquifer tests and potentiometric mapping are insufficient to characterize

1326-466: The global demand for drinkable water. Farming in karst areas must take into account the lack of surface water. The soils may be fertile enough, and rainfall may be adequate, but rainwater quickly moves through the crevices into the ground, sometimes leaving the surface soil parched between rains. The karst topography also poses peculiar difficulties for human inhabitants. Sinkholes can develop gradually as surface openings enlarge, but progressive erosion

1377-456: The karst groundwater flow rates from 0.5 to 7 miles per day (0.8 to 11.3 km/d). The rapid groundwater flow rates make karst aquifers much more sensitive to groundwater contamination than porous aquifers. Groundwater in karst areas is also just as easily polluted as surface streams, because Karst formations are cavernous and highly permeable, resulting in reduced opportunity for contaminant filtration. Well water may also be unsafe as

1428-534: The karst regions of the Balkans, Cvijić's 1893 publication Das Karstphänomen describes landforms such as karren, dolines and poljes . In a 1918 publication, Cvijić proposed a cyclical model for karst landscape development. Karst hydrology emerged as a discipline in the late 1950s and the early 1960s in France. Previously, the activities of cave explorers, called speleologists , had been dismissed as more of

1479-562: The last-named locality having been declared a site of special scientific interest in respect of it. Kegelkarst is a type of tropical karst terrain with numerous cone-like hills, formed by cockpits, mogotes , and poljes and without strong fluvial erosion processes. This terrain is found in Cuba, Jamaica, Indonesia, Malaysia, the Philippines, Puerto Rico, southern China, Myanmar, Thailand, Laos and Vietnam. Salt karst (or 'halite karst')

1530-412: The local South Slavic languages , all variations of the word are derived from a Romanized Illyrian base (yielding Latin : carsus , Dalmatian : carsus ), later metathesized from the reconstructed form * korsъ into forms such as Slovene : kras and Serbo-Croatian : krš , kras , first attested in the 18th century, and the adjective form kraški in the 16th century. As

1581-647: The most dramatic of these formations can be seen in Thailand 's Phangnga Bay and at Halong Bay in Vietnam . Calcium carbonate dissolved into water may precipitate out where the water discharges some of its dissolved carbon dioxide. Rivers which emerge from springs may produce tufa terraces, consisting of layers of calcite deposited over extended periods of time. In caves, a variety of features collectively called speleothems are formed by deposition of calcium carbonate and other dissolved minerals. Interstratal karst

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1632-584: The other symbols alongside the column. Columns are constructed from the stratigraphic base upward and should be plotted first in pencil in order to insure spaces for gaps at faults and unconformities. Sections that are thicker than the height of the plate can be broken into two or more segments, with the stratigraphic base at the lower left and the top at the upper right. Bedding and unit boundaries are drawn horizontally, except in detailed sections or generalized sections of distinctly nontabular deposits, as some gravels and volcanic units”. The following elements of

1683-709: The period. Sedimentation resumed and further limestone strata were deposited on an irregular karst surface, the cycle recurring several times in connection with fluctuating sea levels over prolonged periods. Pseudokarsts are similar in form or appearance to karst features but are created by different mechanisms. Examples include lava caves and granite tors —for example, Labertouche Cave in Victoria, Australia —and paleocollapse features. Mud Caves are an example of pseudokarst. Karst formations have unique hydrology, resulting in many unusual features. A karst fenster (karst window) occurs when an underground stream emerges onto

1734-418: The right conditions. Subterranean drainage may limit surface water, with few to no rivers or lakes. In regions where the dissolved bedrock is covered (perhaps by debris) or confined by one or more superimposed non-soluble rock strata, distinctive karst features may occur only at subsurface levels and can be totally missing above ground. The study of paleokarst (buried karst in the stratigraphic column )

1785-780: The river flows into a cave in a formation known as the Madison Limestone and then rises again 800 m ( 1 ⁄ 2  mi) down the canyon in a placid pool. A turlough is a unique type of seasonal lake found in Irish karst areas which are formed through the annual welling-up of water from the underground water system. Main Article Aquifer#Karst Karst aquifers typically develop in limestone . Surface water containing natural carbonic acid moves down into small fissures in limestone. This carbonic acid gradually dissolves limestone thereby enlarging

1836-524: The river flows through forests and wetlands. It discharges into Pärnu Bay ; the city of Pärnu lies where the river enters the sea. The catchment area of the river is roughly composed of Lower Silurian deposits to the north of the river from the sea to where it merges with the Navesti , and from there north of Navesti, and to the south of this line is composed of largely Middle Devonian deposits . Near Tori , sandstone outcroppings, cliffs and caves border

1887-541: The river has been called the "Estonian Mississippi ". The river typically floods at spring, but also after heavy rains in autumn and summer, and the maximum amount of recorded water in the runoff at a hydrological station in Oore has been measured to be more than 100 times that of the minimum. The flat landscape aggravates the effects of flooding, and large stretches along the river are characterised by flood meadows , flood plain forests and swamp forests . Flood plain forests of

1938-461: The river near the town of Sindi and has been dated to circa 7,500 BC. Karst Karst ( / k ɑːr s t / ) is a topography formed from the dissolution of soluble carbonate rocks such as limestone and dolomite . It is characterized by features like poljes above and drainage systems with sinkholes and caves underground. There is some evidence that karst may occur in more weathering -resistant rocks such as quartzite given

1989-432: The river. In its northern and eastern course, the river runs over a thin (from 5 metres [16 ft] down to as little as 1 metre [3.3 ft]) layer of topsoil , while closer to the sea the topsoil can be as deep as 60 metres (200 ft). The variations in runoff from the river are great, due at least in part to the fact that the river catchment area lacks any large lakes. For this reason, and due to its meandering form,

2040-434: The same regular manner and with essentially the same intensity throughout geologic time, and that past geologic events can be explained by phenomena and forces observable today; the classical concept that 'the present is the key to the past'.". Law of Original Horizontality : sedimentary rocks are always deposited as horizontal, or nearly horizontal, strata, although these may be disturbed by later earth movements. This law

2091-461: The stratigraphic column must either be a structural column, in which the units are stacked with respect to how they are observed in the field to have been moved by the faults, or a time column, in which the units are stacked in the order in which they were formed. Stratigraphy is a branch of geology that concerns the order and relative position of geologic strata and their relationship to the geologic time scale . The relative time sequencing requires

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2142-464: The stratigraphy of as many separate areas as they can, prepare a stratigraphic column for each, and combine them in an attempt to understand the regional geologic history of the area”. Principle of Uniformitarianism : defined in the authoritative Glossary of Geology as "the fundamental principle or doctrine that geologic processes and natural laws now operating to modify the Earth's crust have acted in

2193-649: The surface between layers of rock, cascades some distance, and then disappears back down, often into a sinkhole. Rivers in karst areas may disappear underground a number of times and spring up again in different places, even under a different name, like Ljubljanica , the "river of seven names". Another example of this is the Popo Agie River in Fremont County, Wyoming , where, at a site named "The Sinks" in Sinks Canyon State Park ,

2244-415: The surface, complex underground drainage systems (such as karst aquifers ) and extensive caves and cavern systems may form. Erosion along limestone shores, notably in the tropics , produces karst topography that includes a sharp makatea surface above the normal reach of the sea, and undercuts that are mostly the result of biological activity or bioerosion at or a little above mean sea level . Some of

2295-1002: The system ( pyrite or hydrogen sulfide ) to form sulfuric acid (H 2 SO 4 ). Sulfuric acid then reacts with calcium carbonate, causing increased erosion within the limestone formation. This chain of reactions is: This reaction chain forms gypsum . The karstification of a landscape may result in a variety of large- or small-scale features both on the surface and beneath. On exposed surfaces, small features may include solution flutes (or rillenkarren), runnels , limestone pavement (clints and grikes), kamenitzas collectively called karren or lapiez. Medium-sized surface features may include sinkholes or cenotes (closed basins), vertical shafts, foibe (inverted funnel shaped sinkholes), disappearing streams, and reappearing springs . Large-scale features may include limestone pavements , poljes , and karst valleys. Mature karst landscapes, where more bedrock has been removed than remains, may result in karst towers , or haystack/eggbox landscapes. Beneath

2346-459: The type found by the shores of the river Pärnu are uncommon in Estonia and in the rest of Europe, where few have been preserved. The flood meadows along the river have decreased in numbers due to the lack of tending to them; in recent years however, efforts have been made to restore several of them. The Sindi Dam on the main-stem Parnu was removed in 2018–2019. Other dams on the Parnu will be removed in

2397-449: The vertical location of rock units in a particular area. A typical stratigraphic column shows a sequence of sedimentary rocks , with the oldest rocks on the bottom and the youngest on top. In areas that are more geologically complex, such as those that contain intrusive rocks , faults , and/or metamorphism , stratigraphic columns can still indicate the relative locations of these units with respect to one another. However, in these cases,

2448-461: The water may have run unimpeded from a sinkhole in a cattle pasture, bypassing the normal filtering that occurs in a porous aquifer . Sinkholes have often been used as farmstead or community trash dumps . Overloaded or malfunctioning septic tanks in karst landscapes may dump raw sewage directly into underground channels. Geologists are concerned with these negative effects of human activity on karst hydrology which, as of 2007 , supplied about 25% of

2499-515: The western Highland Rim in the eastern United States is at the second-highest risk of karst sinkholes. In Canada, Wood Buffalo National Park , Northwest Territories contains areas of karst sinkholes. Mexico hosts important karst regions in the Yucatán Peninsula and Chiapas . The West of Ireland is home to The Burren , a karst limestone area. The South China Karst in the provinces of Guizhou , Guangxi , and Yunnan provinces

2550-595: The years ahead. The Parnu River dam removals are financed in cooperation with the Estonian Government and the European Union. Undoubtedly, Atlantic Salmon and other fish species will recover in the years ahead. The towns of Pärnu , Paide , Tori , and Türi are all located on the banks of the river Pärnu. The river has been a focal point for human activity in the area for a long time; the oldest discovered settlement in Estonia has been discovered by

2601-487: Was proposed by Nicolaus Steno in the mid-17th century. Law of Superposition : general law upon which all geologic chronology is based: In any sequence of layered rocks, sedimentary or extrusive volcanic, that has not been overturned, the youngest stratum is at the top and the oldest at the base; i.e., each bed is younger than the bed beneath, but older than the bed above it. The law was stated by Steno in 1669. Cross-cutting relationships : cross-cutting relationships

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