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Limestone of St. Euphemia

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Crkva sv. Eufemije

Na mjestu današnje crkve sv. Eufemije tada je bila mala crkvica sv. Juraja, koja ubrzo nakon dolaska sarkofaga postaje pretijesna za sve hodočasnike, pa stanovnici Rovinja početkom 10. stoljeća počinju graditi novu i veću crkvu. Bila je to trobrodna crkva s tri izbočene apside, tada sa drvenim kipovima sv. Juraja i sv. Eufemije, sve do početka 17. stoljeća, kada je postavljen novi, pozlaćeni kameni kip koji je i danas na oltaru svetice.

Sama je crkva zahtijevala sve više popravaka, a i stanovništvo grada je raslo, pa se Rovinjani ponovo odlučuju na gradnju još veće crkve, koje započinje 1725. godine, i traje do 1736. Uskoro su podignuta i tri glavna oltara (1741.), nedugo zatim nabavljene su i orgulje (1754.) a uređenju samog pročelja pristupa se nešto kasnije, polovinom 19. stoljeća. Unutrašnjost crkve obiluje raznim oltarima i slikama, ovdje ćemo nabrojati najznačajnije.

Prvo što ćete u crkvi zamijetiti svakako je središnji oltar sv. Jurja, sv. Marka i sv. Roka, na kojem su kipovi trojice svetaca izrađeni od kararskog mramora, autora Girolama Laureata, venecijanskog majstora. Sa lijeve strane nalazi se oltar Presvetih Sakramenata, bogat mramorom i ukrašen kipovima anđela, dok se sa desne strane središnjeg oltara nalazi oltar sv. Eufemije, zaštitnice grada, nezaobilazni dio za svakog posjetioca crkve. Sam oltar je također bogat mramorom, kameni kip svetice potječe iz 15. st., a iza oltara nalazi se sarkofag u kojemu su pohranjene relikvije sv. Eufemije.

Na zidovima pored sarkofaga nalaze se slike iz 1883. godine, autora Leonarda Riga, koje prikazuju dolazak sarkofaga do rovinjske obale, te mučeništvo sv. Eufemije. Na stropu se nalazi prikaz krunjenja svetice na nebu. Sa desne (južne) strane nalaze se i oltari Gospe od sv. Krunice, zatim oltar sv. Franje Asiškog, oltar sv. Petra, te oltar sv. Mihovila Arhanđela. Na suprotnoj, sjevernoj strani nalaze se redom: oltar sv. Nikole, krstionica, oltar sv. Sebastijana, Gospa od Karmela, te oltar sv. Roka. Od slika vrijedno je spomenuti prikaze sv. Antuna Padovanskog, sv. Ivana Krstitelja, sv. Franje Asiškog, Blažene Djevice Marije. Pored crkve nalazi se zvonik, sedamdesetak godina mlađi, građen po uzoru na zvonik sv. Marka u Veneciji.

Na vrhu se nalazi kip zaštitnice grada, postavljen na ležajeve tako da se okreće oko svoje osi, zavisno od vjetra. Zvonik, zajedno sa kipom, visok je preko 61 metra, a širina pri dnu je nešto manja od 9 metara. Sa njega se pruža prekrasan vidik cijelog Rovinja sa okolicom, a ponekad, za lijepog vremena, vide se i Alpe. Sama crkva široka je 30 metara, a dužina je 51 metar.

Sarkofag sv. Eufemije

U crkvi se nalazi sarkofag uz kojeg se stoljećima prepričavaju legende. Sarkofag je dugačak 212 cm, širok 95 cm, visok 195 cm. U sarkofagu se nalaze svetičine relikvije. Ona je bez lijeve ruke, prekrivena skupocjenom odjećom izvezenom zlatnim ukrasima. Voštana maska pokriva kosti glave. Tu je masku izradila 1953. god. umjetnica Mila Vod. Okrunjena je krunom i u desnoj ruci drži lovorov list. Na sarkofagu se nalaze vratašca kroz koja se može vidjeti unutra, a otvara se za javnost na blagdan sv. Eufemije i prigodom značajnijih događaja u župi.

U Carigradu dolazi na vlast car Nicefor koji je protivnik svetih slika i moći te sarkofag tajanstveno nestaje u 800. godini. Isti taj kameni sarkofag 13. srpnja 800. godine doplovio je do Rovinja. No bio je toliko težak da ga nitko nije uspijevao izvući iz mora. Uto dolazi dječak s parom mladih junica. Kazuje da mu se ukazala Eufemija i dala naputke te bez problema, uz pomoć nejake stoke, izvlači sarkofag iz mora. I ne samo to, nego taj teški sarkofag dovlači do vrha brda gdje je tada bila crkva svetog Jurja koja je od tada preimenovana u Svetu Eufemiju.

Dječarac koji je s dvije junice jedini uspio dovući sarkofag do vrha, pri vuči je stradao pod tim istim sarkofagom. Legenda kaže kako je njegova majka prizvala čudo i dječak je oživio.

Postoji još jedna legenda vezana uz Svetu Eufemiju i Rovinj. Naime, prvo su u ratu s Genovom u 14. st. ukradene svete moći i odnesene u Chioggu. Neko su vrijeme ostale u Veneciji, a 1401. moći sv. Eufemije vraćaju se u Rovinj. Goveda i sva stoka koja je tada bila na lađama u rovinjskoj luci, kod dolaska moći u blizinu Rovinja, po legendi poskakala je u more kako bi dočekali ostatke svetice.

Sarkofag sv. Eufemije smješten je iza istoimenog oltara u južnoj kapeli crkve. Navodi se da datira iz IV. ili V. st. po Kristu (sl. br. 12.), a izrađen je u potpunosti od bijelog grčkog mramora. Njegova izrada je kasnoantička, i ostavlja dojam nedovršenosti. Jedan od najjednostavnijih tipova sarkofaga s malo crteža i dekoracija, kod kojih je česta disproporcija likova, a primjer tome je sarkofag Poklonstva iz Ravenne ili sarkofag Teodorusa iz Ravenne.

Takve su sarkofage klesarske radionice imale u rezervi, da potom naručiocima isklešu reljefe i urežu natpise. Tako jedna strana sarkofaga nije uopće obrađena, jer se pretpostavljalo da će biti prislonjena uza zid.

Sarkofag se otvara vjernicima i danas, na dan grada Rovinja, 16. rujna.

Rukopis na pergamenu iz 14. ili 15. st.

Kultura i tradicija sv. Eufemije iz Rovinja utemeljuje se na prepričavanjima jednog rukopisa na pergamenu. Pretpostavlja se da je od izvornog kasnosrednjovjekovnog kodeksa sačuvano 20 listova, od kojih 18 pisanih. Ovaj rukopis pokazuje se kao djelo koje predaje mučeništvo sv. Eufemije kalcedonske, prenošenje tijela svetice na brdo Ruben, mučeništvo sv. Uršule s još 11.000 djevica, sv. Jakova Isječenog i sv. Jurja, kao i o prijenosu slavne mučenice Eufemije iz Venecije u Rovinj i polaganje u sarkofag. Napisano je s kaligrafskom vještinom u Veneciji oko XIV. i XV. st..

Izvori:

ISTRA.NET

INFO ROVINJ




Što je vapnenac?

Vapnenac je sedimentna stijena sastavljena uglavnom od kalcijevog karbonata (CaCO3) u obliku mineralnog kalcita. Vapnenačke forme najbolje su vidljive i prepoznatljive u toplim, plitkim morskim vodama. Vapnenac je obično biološka (organska) sedimentna stijena nastala taloženjem školjaka, koralja, algi i fekalnih ostataka.

Također, može biti i kemijski (anorganski) formirana sedimentna stijena nastala taloženjem kalcijevog karbonata iz jezera, mora ili oceana.

Nastajanje vapnenca - marinski

Većina vapnenaca nastaje u plitkim, mirnim i toplim morskim vodama. U morskom okruženju lako dolazi do izvlačenja kalcijevog karbonata iz školjaka i kostura potrebnih za formiranje vapnenca. Nakon što morski organizmi izumru njihove oklopne i skeletne krhotine talože se kao sediment koji se pretvara u vapnenac. Njihovi otpadni proizvodi (kakica) također mogu doprinijeti taloženju. Vapnenci nastali na ovakav način nazivaju se biološkim sedimentnim stijenama. Njihovo biološko podrijetlo otkrivamo prisutnošću fosila u stijeni.

Neki vapnenci mogu nastati izravnim taloženjem kalcijeva karbonata iz morske ili slatke vode. Vapnence nastale na ovaj način nazivamo kemijskim sedimentnim stijenama. Po svojoj strukturi manje su obilni od biološkim vapnenaca.

Danas je na Zemlji puno vapnenačko oblikovanih okruženja. Većina ih se nalazi u pličinama između 30 stupnjeva sjeverne geografske širine i 30 stupnjeva južne geografske širine.

Nastajanje vapnenca - isparavanjem

Vapnenac može nastati i isparavanjem. Stalaktiti, stalagmiti i ostali spiljski oblici takvi su primjeri vapnenca. U pećini, kapljice vode cure odozgo kroz pukotine ili pore i dolaze do spiljskih stropova. Prije pada na pod spilje može doći do isparavanja. Kako voda isparava tako se kalcijev karbonat taloži na stropu spilje. Tijekom vremena proces isparavanja može rezultirati nastankom vrhova kalcijeva karbonata na stropu spilje. Takve naslage počinju tvoriti stalaktite. Moguć je i obrnuti proces kada se isparavanje događa na tlu spilje što omogućava nastanak stalagmita.

Vapnenac koji tako tvori spiljske oblike poznat je i kao „sedra“ te pripada kemijskim sedimentnim stijenama. Stijena poznata kao „tuf“ vapnenac je nastao isparavanjem vrućih izvora, obala jezera ili sličnih područja.

Sastav vapnenca

Vapnenac je po definiciji kamen koji sadrži najmanje 50% kalcijevog karbonata u obliku kalcitne mase. Svi vapnenci sadržavaju barem nekoliko postotaka drugih materijala. To mogu biti maleni udjeli kvarca, feldspata, gline, pirita, siderita i ostalih materijala. Također mogu sadržavati veće komade rožnjaka, pirita ili siderita.

Prisustvo kalcijevog karbonata u vapnencu daje mogućnost lake identifikacije stijene, koja se izložena hladnoj otopini 5%-tne solne kiseline – zapjeni.

Vrste vapnenca

Postoji puno naziva koji se koriste za vapnenac. Ti se nazivi temelje na tome kako je stijena nastala, njezinom izgledu, sastavu i ostalim čimbenicima. Slijedi nekoliko najčešćih naziva:

Kreda: meki vapnenac s vrlo finom teksturom obično bijele ili svijetlo sive boje. Uglavnom nastaje od vapnenačkih ostataka ljusaka mikroskopskih morskih organizama, npr. foraminifera ili vapnenačkih ostataka mnogobrojnih vrsta morskih algi.

Kokvina: Slabo-zacementiran (povezan) vapnenac koji je uglavnom nastao od krhotina slomljenih ljusaka.

Fosilizirani vapnenac: kao što mu naziv govori sadrži obilje fosila. Najčešće se radi o školjkama i kostima organizama koji tvore vapnenac.

Litografski vapnenac: gusti vapnenac s vrlo finim i vrlo ujednačenim veličinama zrna koji se pojavljuje u tankim naslagama koje se mogu lagano raslojavati u vrlo glatku površinu. Krajem 18. stoljeća razvijena je litografija. Litografija je postupak nastanaka likovnog djela u kojoj se po vapnenačkoj ploči crta masnom kredom ili litografskim tušem, pri čemu se stvara vapneni sapun. Zatim se ploča prekrije dušičnom kiselinom pomiješanom s arapskom gumom rastopljenoj u vodi. Vapneni sapun odbija zakiseljenu otopinu te su tako njenom djelovanju izloženi samo neiscrtani dijelovi kamena. Nakon toga se kamen ovlaži vodom i prijeđe valjkom premazanim tiskarskom bojom. Vlažna čista površina ne prima masnu boju, prima je jedino crtež (vapneni sapun) koji nije upio vodu. Litografija je omogućila vrlo laganu proizvodnju kopija te je postala jako raširena.

Oolitski vapnenac: sastavljen uglavnom od kalcijevog karbonata "oolites", male sfere nastale koncentričnim taloženjem kalcijevog karbonata na pješčanom zrnu ili ostatku školjke.

Sedra: vapnenac nastao isparavanjem oborina, najčešće u spiljama, nastaju spiljski oblici poput stalaktita ili stalagmita.

Tuf: vapnenac nastao taloženjem voda bogatih kalcijem iz vrućih izvora, obala jezera ili sličnih mjesta.

Fosili

Na svim spomenutim lokacijama, pronaći ćete ne samo lijep primjer sedimentne stijene vapnenca, već i veliki broj fosila. Što su uopće fosili? Oni su sve ono što dokazuje život u prošlim vremenima. Taj se dokaz prošlog života javlja u dva oblika. On može biti izravan ili neizravan.

Izravan dokaz života su fosili koje čine čvrsti dijelovi organizama. U slučaju životinja, to mogu biti fosilizirane kosti ili školjke. Ili, kada su u pitanju biljke, to može biti fosilizirano drvo ili lišće. U nekim slučajevima, fosiliziran može biti i cijeli organizam, i njegovi meki i njegovi čvrsti dijelovi. Primjeri takvih fosila su insekti zarobljeni u jantaru ili mamuti smrznuti u ledu.

Neizravan dokaz života su fosilni tragovi. To su različiti otisci stopala, repova, tragova, koje su organizmi ostavljali, a zatim su fosilizirani. Koproliti (fosilizirana kakica) su također jedan primjer fosilnih tragova.

Klasifikacija

Dva su velika klasifikacijska sustava kojima se služimo prilikom identifikacije i klasifikacije vapnenačkih i karbonatnih stijena: Folkov i Dunhamov.

Folkova klasifikacija

Robert L. Folk razvio je klasifikacijski sustav koji u prvi plan stavlja detaljnu strukturu zrna i naglašava primarnu detaljnost sastava zrna i ostalih materijala u karbonatnim stijenama. Razlikuje tri vrste sastojaka: alokeme (zrna), matriks (uglavnom mikrit) i cement (sparit). Folkov sustav koristi dvodijelne nazive: prvi dio se odnosi na dominantnost zrna, a drugi na prevladavajuće vezivo (mikrit ili sparit). Prilikom korištenja Folkovog sustava preporuča se koristiti petrografov mikroskop jer je lakše odrediti prisutne komponente u svakom uzorku.


Dunhamova klasifikacija

Dunhamova klasifikacija temelji se na strukturnim značajkama. Svako ime temelji se na teksturi zrna koje čini vapnenac. Dunham je 1962. godine objavio svoj sustav klasifikacije koji dijeli stijene u četiri glavne skupine temeljem relativnih proporcija grubljih klastičnih čestica. Dunhanovi nazivi osnova su za određivanje stijena.

Bavio se pitanjem jesu li ili nisu izvorna zrna u međusobnom kontaktu, podržavaju li se međusobno ili su karakteristična vidljiva razgraničenja. Za razliku od Folka, Dunham se bavio poroznošću stijena. Dunhamova klasifikacija je korisnija i kvalitetnija jer se temelji na teksturi, a ne na ispitivanju zrna u uzorku.


Prošećite oko Katedrale te da biste prijavili pronalazak odgovorite na sljedeća pitanja:

1. Opišite teksturu i boju vapnenca na pročelju crkve!

2. Je li vapnenac nastao:

a) marinski (objasnite)

b) isparavanjem (objasnite)

3. Je li vapnenac:

a) biološkog podrijetla (objasnite)

b) kemijskog podrijetla (objasnite)

4. Zašto je Dunhamova metoda klasifikacije bolja od Folkove?

5. Priložite sliku s GPS-om (nije obvezno)

Pošaljite odgovore e-poštom (putem GC profila). Slobodno upišite pronalazak, a ako nešto nije u redu, obavijestit ću vas!




St. Euphemia's church

A small Church of St. George used to be situated where the Church of St. Euphemia is located today. When St. Euphemia's sarcophagus was brought to Rovinj, the Church of St. George became too small for all the pilgrims. In the 10th century the people of Rovinj started building a new, bigger church.

It was a three-nave church with three projected apses and wooden statues of St. George and St. Euphemia. In the beginning of the 17th century, a new gold-plated stone statue was erected which until this day remains on the altar of the Saint.

The church itself required with time more and more reparations and the town population grew, so that the people of Rovinj decided to build an even bigger church. The building process started in 1725, and lasted until 1736. Three main altars were built in 1741, and the organ was installed in 1754. The façade was designed and built in the second half of the 19th century. Many altars and paintings enrich and embellish the church from within.

We will mention the most important ones. When you enter the church, you will first notice the main altar of St. George, St. Marc and St. Rocco with the statues of these three saints built in 'karar' marble, designed by a Venetian master sculptor Girolam Laureat. On the left side, there is the altar of the Holy Sacraments, rich in marble and embellished with statues of angels. On the right side from the main altar, you will see the altar of St. Euphemia, the patron-saint of the town, a part of the church which all visitors should see.

The altar itself is rich in marble, the stone statue of the Saint dates from the 15th century. Behind the altar you will see a sarcophagus in which relics of St. Euphemia are kept. On the walls by the sarcophagus there are paintings dating from 1883, painted by Leonardo Riga. The paintings depict the arrival of the sarcophagus to the coast of Rovinj and the martyrdom of St. Euphemia. On the ceiling there is an image of the coronation of the Saint up in the sky. On the right (southern) side, there are altars of the Lady of the Holy Rosary, St. Francis of Assissi, St. Peter and St Michael the Archangel. On the opposite, northern side, there are: the altar of St. Nicholas, the baptistery, and the altars of St. Sebastian, the Lady of Carmel and St. Rocco.

From the collection of paintings we should mention the images of St. Anthony of Padova, St. John the Baptist, St. Francis of Assissi, and the Holy Virgin Mary. Beside the church there is a bell-tower, built 70 years earlier and designed like the bell-tower of St. Marc in Venice. On the top of the bell-tower there is a statue of the patron-saint, placed on bearings so that it revolves around its axis depending on the wind. The bell-tower and the statue reach the height of more than 61 meters. At the bottom it is a little bit less than 9 meters wide. There is a beautiful view of all Rovinj area from the bell-tower, and sometimes when the weather is good one can even see the Alps. The church itself is 30m wide and 51m long.

Sarcophagus of St. Euphemia

Euphemia was the daughter of a senator named Philophronos and his wife Theodosia in Chalcedon, located across the Bosporus from the city of Byzantium (which later became Constantinople, modern-day Istanbul). From her youth she was consecrated to virginity.

The governor of Chalcedon, Priscus, had made a decree that all of the inhabitants of the city take part in sacrifices to the pagan deity Ares. Euphemia was discovered with other Christians who were hiding in a house and worshipping the Christian God, in defiance of the governor's orders. They were tortured for a number of days, and then handed over to the Emperor for further torture. Euphemia, the youngest among them, was separated from her companions and subjected to particularly harsh torments, including the wheel, in hopes of breaking her spirit. It is believed that she died of wounds from a wild bear in the arena under Emperor Diocletian (284-305).

Around the year 620, in the wake of the conquest of Chalcedon by the Persians under Khosrau I in the year 617, the relics of Saint Euphemia were transferred to Constantinople. There, during the persecutions of the Iconoclasts, her reliquary was said to have been thrown into the sea, from which it was recovered by the ship-owning brothers Sergius and Sergonos, who belonged to the Orthodox party, and who gave it over to the local bishop who hid them in a secret crypt. The relics were afterwards taken to the Island of Lemnos, and in 796 they were returned to Constantinople.

Her relics were later stolen by the Crusaders. The saint's head was taken by the Knights Templar to their preceptory in Nicosia on Cyprus. Today it is believed that the majority of her relics are kept inside Saint Euphemia's basilica in Rovinj, Croatia.

The legend says that during a stormy night the marble coffin containing the remains of the Saint disappeared from Constantinople. Possibly fishermen who were believers loaded it onto their boats hoping that they could transport it to a safe place. In the same year (800) by a miracle it arrived at Rovinj in the sea. The local story says that the inhabitants tried tremendously hard all day using oxen and horses to remove the coffin from the sea. Finally, a young boy was able to achieve this with a pair of young untrained calves. Another version of the story says that it was a poor widow who moved the coffin.

The Rovinj skyline is difficult to imagine without the tall campanile of the church high above the town with its floodlit statue at the highest point, which appears to guard the roofs below. Throughout the passing centuries large numbers of worshippers came from all over Istra (Istria) to visit the coffin in which the Saint's body is preserved on St. Euphemia's Day, September 16th.

Sources:

ISTRA.NET

INFO ROVINJ




What is Limestone?

Limestone is a sedimentary rock composed primarily of calcium carbonate (CaCO3) in the form of the mineral calcite. It most commonly forms in clear, warm, shallow marine waters. It is usually an organic sedimentary rock that forms from the accumulation of shell, coral, algal and fecal debris. It can also be a chemical sedimentary rock formed by the precipitation of calcium carbonate from lake or ocean water.

Limestone-Forming Environment - Marine

Most limestones form in shallow, calm, warm marine waters. That type of environment is where organisms capable of forming calcium carbonate shells and skeletons can easily extract the needed ingredients from ocean water. When these animals die their shell and skeletal debris accumulate as sediment that might be lithified into limestone. Their waste products can also contribute to the sediment mass. Limestones formed from this type of sediment are biological sedimentary rocks. Their biological origin is often revealed in the rock by the presence of fossils.

Some limestones can form by direct precipitation of calcium carbonate from marine or fresh water. Limestones formed this way are chemical sedimentary rocks. They are thought to be less abundant than biological limestones.

Today Earth has many limestone-forming environments. Most of them are found in shallow water areas between 30 degrees north latitude and 30 degrees south latitude.

Limestone-Forming Environment - Evaporative

Limestone can also form through evaporation. Stalactites, stalagmites and other cave formations (often called "speleothems") are examples of limestone that formed through evaporation. In a cave, droplets of water seeping down from above enter the cave through fractures or other pore spaces in the cave ceiling. There they might evaporate before falling to the cave floor. When the water evaporates, any calcium carbonate that was dissolved in the water will be deposited on the cave ceiling. Over time this evaporative process can result in an accumulation of icicle-shaped calcium carbonate on the cave ceiling. These deposits are known as stalactites. If the droplet falls to the floor and evaporates there a stalagmite could grow upwards from the cave floor.

The limestone that makes up these cave formations is known as "travertine" and is a chemical sedimentary rock. A rock known as "tufa" is a limestone formed by evaporation at a hot spring, lake shore, or other area.

Composition of Limestone

Limestone is by definition a rock that contains at least 50% calcium carbonate in the form of calcite by weight. All limestones contain at least a few percent other materials. These can be small particles of quartz, feldspar, clay minerals, pyrite, siderite and other minerals. It can also contain large nodules of chert, pyrite or siderite.

The calcium carbonate content of limestone gives it a property that is often used in rock identification - it effervesces in contact with a cold solution of 5% hydrochloric acid.

Varieties of Limestone

There are many different names used for limestone. These names are based upon how the rock formed its appearance or its composition and other factors. Here are some of the more commonly used.

Chalk: A soft limestone with a very fine texture that is usually white or light gray in color. It is formed mainly from the calcareous shell remains of microscopic marine organisms such as foraminifers or the calcareous remains from numerous types of marine algae.

Coquina: A poorly-cemented limestone that is composed mainly of broken shell debris. It often forms on beaches where wave action segregates shell fragments of similar size.

Fossiliferous Limestone: A limestone that contains obvious and abundant fossils. These are normally shell and skeletal fossils of the organisms that produced the limestone.

Lithographic Limestone: A dense limestone with a very fine and very uniform grain size that occurs in thin beds that separate easily to form a very smooth surface. In the late 1700's a printing process (lithography) was developed to reproduce images by drawing them on the stone with an oil-based ink and then using that stone to press multiple copies of the image.

Oolitic Limestone: A limestone composed mainly of calcium carbonate "oolites", small spheres formed by the concentric precipitation of calcium carbonate on a sand grain or shell fragment.

Travertine: A limestone that forms by evaporative precipitation, often in a cave, to produce formations such as stalactites, stalagmites and flowstone.

Tufa: A limestone produced by precipitation of calcium-laden waters at a hot spring, lake shore or other location.

Fossils

On EarthCache location, you can find not only nice example of sedimentary rock limestone, but also nice examples of fossils. What are fossils, anyway? Well, they are anything that provides evidence of life in past ages. That evidence of life in past ages can come in two types. It can be either direct evidence or indirect evidence of past life.

Direct evidence of life are fossils of hard body parts of organisms. They can be fossilized bones or shells in case of animals. Or it can be fossilized wood or leaves in case of plants. In some cases, the entire organism can be fossilized, together with both soft and hard parts. Example of such fossils are insects trapped in amber or mammoths frozen in ice.

Indirect evidence of life are trace fossils. They are various footprints, trails, marks that were left by organisms and then fossilized. Coprolites (fossilized poo) is also one example of trace fossils.

Classification

Two major classification schemes, the Folk and the Dunham, are used for identifying limestone and carbonate rocks.

Folk classification

Robert L. Folk developed a classification system that places primary emphasis on the detailed composition of grains and interstitial material in carbonate rocks. Based on composition, there are three main components: allochems (grains), matrix (mostly micrite), and cement (sparite). The Folk system uses two-part names; the first refers to the grains and the second is the root. It is helpful to have a petrographic microscope when using the Folk scheme, because it is easier to determine the components present in each sample.

Dunham classification

The Dunham scheme focuses on depositional textures. Each name is based upon the texture of the grains that make up the limestone. Robert J. Dunham published his system for limestone in 1962; it focuses on the depositional fabric of carbonate rocks. Dunham divides the rocks into four main groups based on relative proportions of coarser clastic particles. Dunham names are essentially for rock families. His efforts deal with the question of whether or not the grains were originally in mutual contact, and therefore self-supporting, or whether the rock is characterized by the presence of frame builders and algal mats. Unlike the Folk scheme, Dunham deals with the original porosity of the rock. The Dunham scheme is more useful for hand samples because it is based on texture, not the grains in the sample.


To get the log permission, please answer the following questions:

1. Walk around Church and try to describe the texture AND color of the limestone at facade wall

2. Is this limestone:

a) marine forming environment (explaine)

b) evaporative forming environment (explaine)

3. Is this limestone:

a) biological (explaine)

b) chemical (explaine)

4. Why Dunham’s classification is better than Folk’s classification?

5. Take a photo with GPS (optional)


Please email me your answers in english (via GC-Profile). You don't have to wait for a permission to log. If your answers are incorrect, I will inform you



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