Amfiteatar
Amfiteatar je smješten 200 metara sjeveroistočno izvan gradskih zidina Pule, u skladu s mrežom rimske zemljišne podjele. Smatra se da je gradnja počela već za cara Augusta (27. pr. Kr. – 14. pos. Kr.), a financirala se iz središnje državne blagajne u rimskoj carskoj vlasti. Dvije središnje osi vanjskog zidnog plašta mjere 132,5 m i 105,1 m, a najveća visina iznosi 32,45 m. Amfiteatar je građen u tuskanskom stilu i zauzima površinu od 11.466 m². Procjenjuje se da je mogao primiti približno 23.000 gledatelja. Podignut na padini brijega, na zapadnoj strani, okrenutoj prema moru, pulski amfiteatar ima četiri etaže - povišeni temelj s ulazima i tri kata, dok je u istočnom dijelu na prirodno povišenom terenu zidani dio objekta znatno manji: nad zemljom se izdižu samo dva gornja kata. U glavnoj osi na vanjskom plaštu amfiteatra nalaze se lukovi širine 4 m, veći od ostalih, naglašavajući glavne ulaze (portae pompae). Ulaz na južnom kraju bio je najznačajniji, jer je okrenut prema gradu. Na toj se strani nalazio i glavni ulaz u borilište. Drugi kat gledališta zidan je cijelim opsegom amfiteatra u 72 polukružne arkade. Treći kat pripadao je galeriji ovalnog prstenastog oblika, natkrivenoj kosim krovom od keramičkih ploča i kupa, koja je za razliku od donjih katova prema van bila otvorena u 64 četvrtasta prozora. Vijenac na vrhu drugog kata nosio je postolja za umetanje drvenih jarbola koji su nadvisivali amfiteatar. Opasnost od ispiranja i klizanja terena uslijed kiša umanjena je izgradnjom sustava kanala za prihvat i odvodnju oborinskih voda. Borilište u sredini amfiteatra mjeri 67,9 m po dužoj osi i 41,6 m po kraćoj. Ovalni oblik borilišta bio je idealan za povorke, postrojavanja, razvoj borbene strategije, napredovanje i povlačenje oružanih skupina. Ispod borilišta smještena je pomoćna podzemna prostorija, većim dijelom uklesana u živu stijenu i dijelom nadozidana do potrebne visine. Služila je za držanje kaveza za zvijeri i raznih tehničkih pomagala za pripremu igara. U slučaju lošeg vremena, gledalište se natkrivalo platnom uz pomoć sistema kolutova i užadi. Drveni jarboli, nosači platna, prolazili su kroz predviđene otvore na kamenom oluku. Na drugom kraju, iznad rubova borilišta, nalazio se metalni obruč poduprt okomitim jarbolima. Užad razapeta između vanjskih jarbola i unutrašnjeg metalnog obruča nosila je platno.
Amfiteatar u Puli razlikuje se od ostalih po tome što su u vanjski zidni plašt ukomponirana četiri pravokutna tornja. U njima su bile smještene pomoćne drvene stepenice za uspon do vrha i vodospreme, a osim toga pojačavali su stabilnost zidnog plašta i učvršćivali građevinu. Tornjevi su bili natkriveni kosim krovom od keramičkih ploča i kupa na konstrukciji od drvenih greda. Na vrhu svakog tornja nalazile su se po dvije odvojene vodospreme, koje su se punile kišnicom.
U amfiteatru su se priređivale gladijatorske borbe i lov na životinje. Ulaz na predstave nije se plaćao, ali raspored sjedenja u amfiteatru strogo je pratio društvenu hijerarhiju po bogatstvu i ugledu. U borilištu su održavana javna suđenja i provodila se kazna ad bestias namijenjena ubojicama, razbojnicima i pobunjenicima bez rimskog građanskog prava, pri kojoj su se nenaoružani ili slabo naoružani osuđenici dovodili pred zvijeri. Pripadnici kršćanske zajednice mučeni su na razne okrutne načine, uslijed čega se razvio kult svetaca mučenika. Za amfiteatar u Puli vezuje se povijesna priča o mučeništvu sv. Germana, koji je postao svetac zaštitnik Pule.
Nakon zabrane gladijatorskih predstava početkom V. st., amfiteatar je prepušten propadanju i odnošenju građevinskog kamena, no uvijek je ostao javnim vlasništvom. Stoljećima je plijenio pažnju putopisaca, umjetnika i arhitekata. Grafički prikazi amfiteatra našli su se u djelima o arhitekturi istaknutih autora kao što su Sebastiano Serlio, Andrea Palladio, Antoine De Ville, Thomas Allason. Amfiteatar je krasio grafičke vedute Pule, geografske karte kao i brojne grafičke mape o starim spomenicima i znamenitostima, među čijim se autorima ističu Giovanni Battista Piranesi, Jacob Spon i George Wheler, Robert i James Adam, Charles Louis Clerisseau, Louis François Cassas i August Tischbein. Arheološka istraživanja amfiteatra otpočela su sredinom XVIII. st., a njegovo konzerviranje i restauriranje nastavlja se i danas.
OSTALE PULSKE ZNAMENITOSTI:
Augustov hram
Slavoluk Sergijevaca – Zlatna vrata
Kaštel
Malo rimsko kazalište
Katedrala uznesenja Blažene Djevice Marije
Crkva i samostan sv. Franje
Kapela sv. Marije Formoze
Mornaričko groblje
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 amfiteatra te da biste prijavili pronalazak odgovorite na sljedeća pitanja:
1. Opišite teksturu i boju vapnenca na vanjskoj strani amfiteatra!
2. Jesu li ovi vapnenci biološki ili kemijski vapnenci? Objasnite?
3. Pretražite lokaciju i pronađite barem jedan fosil. Je li taj fosil direktan ili indirektan dokaz o prošlom životu? (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!
The amphitheater
The amphitheater is located approximately 200 meters to the northeast outside of the city walls of Pula, in accordance with the Roman land division grid. It is believed that construction works began already during the period of Augustus (27 BC – 14 AD), and that they were financed by funds from the central state treasury of the Roman imperial government. The two central axes of the outer wall mantle of the amphitheater at Pula measure 132.5 and 105.1 m, and its maximum height measures 32.45 m. The amphitheater was erected in Tuscan style, covering an area of 11, 466 m2. It is estimated that it could receive approximately 23,000 spectators. Built on the slope of a hillock, on the western side facing towards the sea, the amphitheater at Pula has four floors - the raised foundations with entrances and three stories, whereas in its eastern section it lies on a naturally elevated terrain, the masoned part of the structure being, hence, considerably lower: only the two upper stories rise from the ground. Located in the main axis on the outer mantle of the amphitheater, are arches measuring 4 m in width, which are larger than the rest, accentuating thus the main entrances (portae pompae). The entrance on the southern end of the longer axis of the amphitheater was the most important one because it faced the city. It was on this side that the main entrance into the fighting ring was likewise located. The second story of the auditorium was masoned along the entire circumference of the amphitheater and opens up into 72 semi-circular arcades. The third story belonged to an oval, ring-shaped gallery that was roofed with a slanting roof consisting of ceramic tegulae and imbrices, which unlike both inferior stories opened to the outside with 64 square windows. The cornice at the top of the second story supported the square podia with rectangular hollows for the insertion of wooden masts that topped the amphitheater. The potential danger of erosion and sliding land due to rainwater was lessened with the construction of a system of channels for dealing with unwanted rainwater. The fighting ring (arena) situated in the middle of the amphitheater measures 67.9 meters alongside its longer axis, and 41.6 meters along the shorter one. The oval shape of the fighting ring was ideal for processions, line-ups, and the development of fighting strategies as well as the advancement and retreat of armed combat groups. Located underneath the fighting ring was an auxiliary subterranean chamber that was for the most part carved out of bedrock and partially masoned up to the necessary height. It served as storage for cages that housed the beasts, and for various technical tools used in the organization of the spectacles. In case of bad weather the auditorium was covered with a tarpaulin, using a system consisting of sets of pulleys and ropes. Wooden masts carrying the tarpaulin went through the special openings on the stone gutter. Located on the other end, above the edges of the arena, was a metal ring supported with vertical masts. The ropes that were extended between the exterior masts and the interior metal ring carried the tarpaulin.
The amphitheater at Pula differs from the rest in that it features four rectangular towers that had been included into the outer wall mantle. Each of them housed an auxiliary wooden staircase used to climb to the top and to the water reservoirs, and besides, the towers increased the stability of the wall mantle and strengthened the structure on the whole. The towers were covered with a slanting roof made of ceramic slabs and roof tiles resting on a structure of wooden beams. At the top of each tower were two separate water reservoirs that were filled with rainwater.
Gladiator fights and hunting spectacles were held at the amphitheater. The spectators did not have to pay an entrance fee; however, there was a rigid seating scheme in the amphitheater, which mirrored in detail the existing social hierarchy regarding wealth and prominence. Public legal proceedings were also held in the fighting ring, and the ad bestias punishment was executed there, intended for murderers, bandits and mutineers who did not enjoy Roman civic rights, it consisted of unarmed or poorly armed convicts being brought to the beasts. Members of the Christian community were tortured in amphitheaters in many cruel ways, resulting in a massive development of the cult of martyr saints. A historical tale about the martyrdom of St. Germanus is linked with the amphitheater at Pula, who later became the patron saint of Pula.
After spectacles involving gladiators were outlawed at the beginning of the 5th century, the amphitheater was left to dilapidate, and it was perceived as a valuable source of readymade building material, though always remaining a public property. The amphitheater has for centuries attracted the interest of travel writers, artists and architects. Drawings of the amphitheater are to be found in works dealing with architecture, written by some of the most distinguished authors such as Sebastiano Serlio, Andrea Palladio, Antoine De Ville and Thomas Allason. The amphitheater adorned panoramas of Pula, geographical maps as well as numerous albums of drawings depicting antique monuments and other sights, which were drawn by artists such as Giovanni Battista Piranesi, Jacob Spon and George Wheler, Robert and James Adam, Charles Louis Clerisseau, Louis François Cassas and August Tischbein. Archaeological explorations of the amphitheater have started in the middle of the 18th century, works on its conservation and restoration are still continuing to the present day.
OTHER ATRRACTIONS IN PULA:
Temple of Augustus
Triumphal Arch of the Sergi – Golden Gate
Castle
Small Roman Theater
Cathedral of the Assumption of the Blessed Virgin Mary
Church and Monastery of St. Francis
Chapel of St. Maria Formosa
Naval cemetry
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 amphitheater and try to describe the texture AND color of the limestone at outside walls!
2. Is this limestone biological or chemical limestone? Why?
3. Search the EC location and find at least one fossil. Is this fossil direct evidence or indirect evidence of past life? (explain)
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
