GEO-TRAIL “BIŠEVO”: THE STORY OF ROCKS EMERGED FROM LIFE!
1. INTRODUCTORY PANEL

You have set your foot on the island of Biševo in the Vis archipelago. Biševo boasts two monuments of nature. The Blue Cave is the most attractive monument of nature in the archipelago, featuring a unique effect produced by sunrays in the cave interior that simply leaves you breathless. The other monument of nature, the Monk Seal Cave, is only a mile away. It is the longest semi-submerged cave in the Adriatic, with the total length of 160 meters. As its name implies, this cave used to be a hiding and breeding ground for the Mediterranean monk seal species, which reared their young on a small pebble beach at the end of the cave hall.

This trail describes the geological origin of the island of Biševo, as well as the cultural and natural heritage of the inhabitants of this beautiful, exotic island. 

In the Mesozoic or The Age of Dinosaurs and the beginning of the Cenozoic or the Age of Mammals, Biševo was located in a tropical belt in the middle of an ancient Thetis ocean. Biševo was a part of a small continent located between Europe and Africa called the Adriatic Carbonate Platform, which was covered by shallow and warm sea teeming with life and numerous organisms. Biševo’s sedimentary layers were built from numerous shells and remains of these organisms.When the Adriatic Carbonate Platform collided with Europe, these sediments were tectonically elevated, resulting in the formation of the Dinaric mountains and the present day islands of the Vis archipelago. The Quarternary period, when the sea level was as 140 meters lower than today, was marked by dry and cold Ice Age. Strong winds carried the sand from the steppes to the surrounding hills, present day islands, and it is for this reason that Biševo has beautiful sand beaches and fertile soil which yields the finest quality grape.

2. THE BLUE CAVE – BEAUTY BEYOND WORDS

The Viennese painter Eugen baron Ranssonet, discovered the Blue Cave on the island of Biševo. In the Viennese daily Neue Freie Presse, on Thursday, August 7th 1884, no. 7165, an article by Baron Eugen Ransonnet was published: Die blaue Grotte der Insel Busi. This article sparked a massive interest of the Austrian public for the natural beauty of the coast and islands of the Austro-Hungarian Empire. It was a sensational news story about the discovery of the natural Adriatic phenomenon - The Blue Cave on the island of Biševo, whose beauty, as Ransonnet believed, tops the more famous Grotta Azzurra on the island of Capri which was then considered the most beautiful sea cave in the world.

As we leave behind a bright summer day and enter the dark tunnel of Biševo’s Grod Balon cliff, we soon encounter that deep blue beauty which flashes at us from the sea, that colour which turns all objects and bodies immersed in it into liquid silver. And we know with certainty that we are in a mythical place, that we have crossed over from reality to a supernatural realm, on a small boat, and into some unexplicable mythical ambient of a sea deity which fills us with never before encountered feelings and miraculous strength. We know with certainty that we will come out of this temple of beauty as different people than the ones we were before the entrance.

3. STONE BALLS FROM THE BOTTOM OF THE ANCIENT SEA

The youngest layers from the stone "book" of the island of Biševo are Paleogene limestones formed during the Age of Mammals. Like small pieces of rocks tumbling down a snowy slope, these balls were formed by the sliding of the sediment of biogenic material down the slope of the sea bottom, where they formed nodular ("ball-like") textures.

ThePaleogene limestones built the central part of the island of Biševo, and could be discerned by the harsh (rough) surface and nodular (wavy) layers. They are easily decomposed into calcareous sand which was carried by the wind to the sandy plains and the valleys during the last Ice Age. Sand was formed of the millions of tiny calcareous testsof protozoa (foraminifera), algae, sea urchins, shells and their debris. The accumulated grains of sand in the sediment are subsequently cementedinto a solid rock - limestone.

4. POSIDONIA, A SEAGRASS SPECIES

Approximately 100-120 million years ago, some land plants became underwater plants again. One of such plants is also the Posidonia oceanica, an aquatic plant bearing flowers and fruits whose exclusive habitat is the Mediterranean Sea. The posidonia seagreass species is also the most widespread endemic seagrass of the Mediterranean. It was named by the famous Swedish botanicist Linné, after the Greek sea god Poseidon.

Posidonia plays an important role in the ecosystem of coastal areas in multiple ways. In posidonia meadows there are as many as 400 various types of plants and a couple of thousand animal species. Only upon careful inspection we notice that the seemingly empty posidonia meadows are actually teeming with life and are densely populated habitats of marine life. On posidonia’s leaves a plentitude of plant and animal species flourish. We call these organisms epiphytes (from the Greek wordsepimeaning "on" andphytonmeaning "plant"), and they are a food source to fish, mollusks and crustaceans. Due to their elongated leaves and a developed network of rhizomes, the posidonia catches sediment particles, adding to the sea’s transparency. In the autumnal period, the posidonia seagrass, also known as "lažina" in Dalmatia, protects Biševo’s sandy beaches from sand erosion. It has been estimated that the island of Biševo is surrounded by 200 hectars of posidonia, which together with sea caves, corallogenic reefs, sand beaches and the submarine world, make up the area called “The Biševo Sea” within the ecological network Natura 2000. Just like continental forests, posidonia meadows represent the "climax" community (i.e. the final stage in the long ecological succession) in the coastal submarine area, which produces significant amounts of oxygen crucial to life. Due to its slow growth, between 1 and 7 cm on average per year, posidonia meadows take a long time to become restored. It is therefore of exceptional importance to take all preventive measures to protect posidonia, by regulating the negative human impact – constructing the necessary sewage systems, prohibiting the filling of coastal areas, prohibiting usage of driftnets as fishing tools, and the regulation of anchoring.

The Mezuporat Bay on Biševo has an ecological mooring system. The boats are tied to the floating buoys, so as to avoid the repetitive anchoring to the seabed where the sensitive posidonia meadows are located. Throughout history posidonia was usedas fertilizer, material for the covering of roofs and the construction of resting mats. In the Lazaret cave in Nice, the remains of a bed made from posidonia were found, which people have used from 10 000 years ago.

5. TECTONIC FORCES AND THE FAULT PLANE

In the hinterland of the Blue Cave the consequences of the violent dynamics of the Earth's crust can be seen. Due to the action of tectonic forces and the slow movement of large blocks of the upper parts of the crust, the rocks became fractures resulting in the blocks moving along these fractures – flat surfaces known as the faults. Traces of tectonic movement or scraping of the Blue Cave’s block against the central mass of rocks on Biševo, can be seen along the sleek fault plane called paraclasis. This fault intersects the rock so it can be traced from the southern entrance to the Blue Cave to the northern, narrow passage between the shore and a small islet along which the boats with the Blue Cave visitors are sailing.

The Blue Cave was probably formed through selective erosion (abrasion),during the interaction of tectonic (diapiric) rise of the island and rises of the sea-level after the last Ice Age. Namely, the rocksof the terrestrial phase are softer than the surrounding carbonate rock, and that very horizon (a ‘page’) from the stone "book" is presumably located in the level of the submerged parts of the Blue Cave. Waves propelled by strong southern winds crashed into and washed against the softer rocks, carving our a large hole in them – the present day Blue Cave. Erosion is faster along the intersection of the cracks in the rocks and the holes are still forming along the cliffs.

6. COEXISTENCE WITH THE ROCKS

People have been exploting rocks since prehistoric times. On the island of Biševo there are various types of limestones which occur naturally in various forms - as massive, thickly bedded, nodular (wavy), and platy. This natural material was hence used for construction of houses and other objects on the island.

On the island of Biševo’s flatlandsthere is a spacious plain (Poje, meaning field in Croatian) with the largest homonymous settlement in this picturesque countryside. The Church of Saint Sylvester is the largest building on the island, and is made of various types of carefully selected Biševo limestone (carved blocks, boulders and plates). The second largest building on the island is the former elementary school, the site of the future visitor info centre. This building was also constructed from the local Biševo limestone, as are most of the other objects on the island.

The people of Biševo used various types of geological substrate for a variety of crops, whose fruits allowed life on this remote island. Because of specific geological conditions, the highest quality soil on the islands developed in the area surrounding Poje. A lovely view of the island of Svetac stretches from this plain. Springtime ushers in true Mediterranean heaven here, when the macchia bush blossoms into a spectacular floral oasis.

7. SAINT SYLVESTER’S CHURCH ON BIŠEVO

In 1050 a priest from Split by the name of Ivan erected a church on Biševo’s plateau and consecrated it to Pope St. Sylvester (314 – 335), who was the first in the history of Christianity to secure Christians’ rights to publicly declare their faith. Father Ivan gave the church over to the Benedictines from the Tremiti islands. St. Sylvester’s Church was built in Pre-Romanic style, but its original configuration was changed over the subsequent centuries. Benedictines arrived to Biševo at that period and erected their monastery in the vicinity of the church.

In the tumultuous period of battles between Venice and Byzantium over rule of these areas, the monastery of St. Sylvester on Biševo turned to Pope Alexander III for protection. On May 2th, 1181, the Pope signed a privilege under which he placed this monastery. The letter begins with the Pope’s address to the monastery’s superior, abbot Urso: „Alexander the Bishop, servant of God’s servants, to his dearest son Urso, abbot of St. Sylvester’s monastery on the island of Biševo and his monastic brethren, the present and future ones, for all times.“

One of the oldest paintings of Madonna in Croatia, the work of the proto-Venetian painting style from the 13th century (dated 1220), was preserved in this church on Biševo – Madonna from Biševo was believed to have miraculous powers.

8. THE BIŠEVO SCHOOL

In 1921 the first school on Biševo was founded in a private family home in the village of Porat. The primary school educated children in grades 1-4. In 1937 the inhabitants of Biševo built their own school building in the village Poje. The school was actively working until 1961, when it had to be shut down due to a small number of school children. Before World War 2, Biševo had 350 inhabitants, in comparison to the 2011 population census which registered only 11 permanent residents on the island. Many of its former residents have permanently emigrated to the United States, mainly San Pedro in California or to Australia.

A pupil’s notebook from 1956 was found in this building. In it was an essay on the subject of their native island:

Biševo, February 14th, 1956. Fifth school essay

My village

“My village is called Biševo, it is in the middle of the Adriatic. People here are farmers and fishermen. My village is surrounded with hills and a small forest. The houses are scattered around and people say it’s quite desolate. My village has no railroads and power stations, no movies or theatres. We don’t get the big steamboats as in the big cities. My village is small and it has one world famous cave.”

These words were written down by a little boy named Petar on a cold winter morning of 1956. A third-grader, Peter wrote about his island in the middle of the Adriatic, known for its Blue Cave.

In 1990 the town of Komiža in association with the University of Zagreb, initiated the project of restoration of the Biševo school building, with the idea it would eventually house an international research centre.This happened around the time when the island of Vis and its archipelago came out of isolation after 45 years of being a military zone, bringing the first foreign tourists to the island. Everyone hoped that they might use this historically unique moment to start a sustainable development programme on this desolate archipelago. This project was stunted by the onset of the Homeland War but the idea remained alive, only to be realized 28 years later, when the Biševo school building will undergo renovation that will transform it into a new Interpretation Centre on Biševo.

9. THE TERRESTRIAL PHASE ON THE ISLAND IN THE MIDDLE OF THE OCEAN

At the end of the Age of Dinosaurs, at the end of the Cretaceous, the wider area of the island of Vis emerged on the surface. Once exposed on the surface, the limestone rocks slowly became subject to the new, terrestrial conditions. Much like present day "muddy" rains which contain desert dust from the Sahara, back in the day the openings in the paleokarst were filled with the reddish-brown dust. Today we can find this dust in the form of reddish-brown petrified soil.

Acting as a type of time capsule, the ground has preserved animal bones as a memorial of the time when, instead of present-day islands of the Vis archipelago, there was once here a large island in the middle of the Tethys Ocean. The islanders were dinosaurs, crocodiles and other land animals.

The sea life flourished again after the sea flooded this area again during the Paleogene period. During this period an entirely different type of limestone rocks were deposited. Unlike limestone rocks of the Cretaceous period, these took on the form of biogenic limestones, not the reddish-brown but light-brown in colour.

10. AEOLIAN SAND FROM THE ICE AGE

In the youngest geological period – Quaternary, you would not be able to come to Biševo by boat, but with a jeep. During the Ice Age of that period the climate was dry and cold and the sea level was 140 meters lower than today. Instead of the seabed, the Adriatic steppe was the landscape that surrounded us, and the islands were scattered peaks of the hills. The steppe landscape was dominated by sand which the winds scattered over the surrounding hills. Present-day sand fields are just erosive remnants of these larger sandstone roofs. Such specific soil has enabled the cultivation of high quality grapevines and has become home to numerous populations of land snails. Most of the sand was partly washed by rains into the valleys that were submerged by the sea after the last Ice Age. For this reason we can find on this island some of the most beautiful sandy beaches of the archipelago: Porat and Sarbunora.

11. PAVAO MARTINIS FROM BIŠEVO – KING OF SALMON IN USA

He was born on the island of Biševo in 1893. Before doing his few years of military service in the Austro-Hungarian army, he decided to go to the USA in 1913. He boarded the steamboat Martha Washington in Trieste and, after an eighteen-day journey, disembarked in New York without knowing a word of English and carrying only $22 in his pocket, but he possessed enormous fishing experience gained from fishing with his father in his early youth. He arrived in Astoria, in Oregon state. Hearing that there were fishermen from Komiža in Tacoma, he set off in search of fishing work. It was a pioneering time of fishing in Alaska, when fishing was still powered by sail and oar. They went terrible conditions for salmon fishing.

Pavao Martinis went down in the history of American fishing not only because of the record catches of salmon in Bristol Bay and the Bering Sea, but also as the first American fisherman who discovered salmon in the rich and dangerous waters of the Aleutian Islands. America acknowledged him officially for his fishing endeavours by awarding him the title King of Salmon, given to him by the president of the USA Dwight D. Eisenhower in 1956.

12. THE STONE “BOOK” FROM THE AGE OF DINOSAURS

Sarbunora, one of the three coves on Biševo, was named after the Komiža expression for sand – “sarbun”. On the north-western edge of the island the whole epoch of the Earth’s crust emerged from the sea depths in the form of the “books”. Collision of the Adriatic Carbonate Platform and Europe has resulted in a tectonic rise which shaped the Dinaric mountains and these hills, present-day islands of the Vis archipelago. Spectacular cliffs we find all along the coasts of these islands tell us of this exciting geological event. Every ‘page’ of this geological book tells us a thousand year old story. The rich records of “Poseidon’s Library” are found all along the Salbunora Bay, andare decorated with fossilized ornaments that depict the contours and textures of prehistoric life. Carbonate sludge and sand, later tempered (litified) into a layer of solid limestone rock, formed from chiseled parts of fossil shells.

In the lagoons of the Adriatic Carbonate Platform, buried in sludge, at the bottom of the warm tropical sea, many of the former shellfish were inhabited by rudists. The asteroid impact 66 million years ago sealed the fate of these prairies and all of their life forms, includingdinosaurs. In the period of the rising sea level, crusts from shellfish rudists and snails were crushed into fine sand and swirled around by sea currents, which createdsand bars.

13. MARTIN BOGDANOVIĆ - THE MAN FROM BIŠEVO WHO OPENED THE DOOR OF THE PACIFIC

The story of this important man from the island of Biševo, which was passed down by word of mouth, tells us how, one day, Martin was busy tilling his vineyard and in the process broke the handle of the hoe. He was in a dilemma whether to fix it or simply go to America. He opted for America after all. He had just finished his naval service in the Austro-Hungarian Navy and was free to leave his homeland.

In San Diego he became a fisherman. When he increased his income from fish trading, he decided, in 1917, to open his own factory. But to enable deep sea fishing, far away from the shore, it was necessary to preserve the fish on the boat. In the book entitled The Port of Los Angeles it is stated that Martin Bogdanović was considered to be the innovator who first used crushed ice to preserve fish. The door to the vastness of the Pacific was open.The strength of his cannery was based on the exceptional capabilities and experiences of the people from his homeland. Martin Bogdanović came from a poor country into a land which offered opportunity to the competent and the courageous, and so, the poor fisherman from the island of Biševo became the greatest name in American fishing history.

NOVOSTI!

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