Rock of Gibraltar
The Rock of Gibraltar is a monollithc limestone promontory forming the body of the British overseas territory of Gibraltar, on the south-western tip of the Iberian Peninsula, to which it is joined by just a low sand-bar. The Rock stands 1,398 feet high at its highest summit, O'Hara's Battery. It stands between the Mediterranean Sea and the Atlantic Ocean, commanding the Strait.
The Rock has a most distinctive shape, and was once described in less happy times as "a couchant lion threatening Spain". Its north face is an almost sheer rise from the isthmus to a peak, while to the south it tumbles down more gently to Europa Point, the territory's southernmost spit.
On the lower slopes of its western side spreads the City of Gibraltar, while the Rock's eastern scarp plunges to the Mediterranean Sea, leaving just a narrow strip of land for the village of Catalan Bay. The west side of the Rock is threaded with narrow roads reaching upwards to Gibraltar's more exclusive homes and ultimately to the Upper Rock, which is a nature reserve. The main city was once clustered in a narrow thread on the lower Rock, from the Landport Gate and Casemates southward along Main Street and up and over to Europa Point, though reclamation from the sea has allowed the city to spread far westward of the Watergate and indeed north of the Landport Gate.
The Rock is Crown property. Most of the Rock's upper area is covered by a nature reserve], which is home to around 250 Barbary macaques, the famous Gibraltar apes. The apes, as well as a labyrinthine network of tunnels, attract a large number of tourists each year.
The Rock of Gibraltar was one of the "Pillars of Hercules" and was known to the Ancient Romans as Mons Calpe, the other pillar being Mons Abyla (now known as Jebel Musa) on the African side of the Strait of Gibraltar. In ancient times the two points were said to mark the limit to the known world, a myth originally known to the Phoenicians.
The Latin name of Calpe appears in the motto beneath the arms of Gibraltar (and is still seen in local commercial names. The Rock's Arabic name, Jabal al Tariq ("the Rock of Tariq") gave rise to its name in English name.
The Moorish Castle
The Moorish Castle is a relic of the Moorish occupation of Gibraltar, which lasted for 710 years. It was built in the year 711, when Tariq ibn-Ziyad, the Berber chieftain first landed on the Rock that still bears his name; Jebel al-Tariq.
The principal building that remains is the Tower of Homage, a massive building of brick and very hard concrete called tapia. The upper part of the tower housed the former occupants' living apartments and Moorish bath.
The Galleries or the Great Siege Tunnels are a unique system of underground passages dug through the Rock.
The first of these passages was dug towards the end of the Great Siege of Gibraltar, a four year siege which lasted from 1779 to 1783. General Elliot, afterwards Lord Heathfield, who commanded the garrison throughout the siege, was anxious to bring flanking fire on the Spanish batteries in the plain below the North Face of the Rock. On the suggestion of Sergeant Ince of the Royal Engineers, he had a tunnel bored from a point above Willis's Battery to communicate with the Notch, a natural projection from the North face. The plan was to mount a battery there. There was no intention at first of making embrasures in this tunnel, but an opening was found necessary for ventilation; as soon as it had been made a gun was mounted in it. By the end of the siege, the British had constructed six such embrasures, and mounted four guns.
The Galleries, which tourists may visit, were a later development of the same idea and were finished in 1797. They consist of a whole system of halls, embrasures, and passages, of a total length of nearly 997 feet. From them, one may see a series of unique views of the Bay of Gibraltar, the isthmus, and Spain.
The Second World War onwards
When the Second World War broke out in 1939, the authorities evacuated the civilian population to Morocco, the United Kingdom, Jamaica, and Madeira so that the military could fortify Gibraltar against a possible German attack. By 1942 there were over 30,000 British soldiers, sailors, and airmen on the Rock. They expanded the tunnel system and made the Rock a keystone in the defence of shipping routes to the Mediterranean.
A secret plan, revealed only in 1997 was called "Operation Tracer", to conceal servicemen in tunnels beneath the Rock in case the Germans captured it. The team in the rock would have radio equipment with which to report enemy movements. A six-man team waited under cover at Gibraltar for two and half years. The Germans never got close to capturing the rock and so the men were never sealed inside. The team was disbanded to resume civilian life when the war ended.
Despite long sieges it seemed that there was nothing that could destroy the Rock or its people. This history has inspired the saying "solid as the Rock of Gibraltar". The motto of the Royal Gibraltar Regiment and even Gibraltar itself is Nulli Expugnabilis Hosti (Latin for "No Enemy Shall Expel Us"), which reflects this invincibility.
Upper Rock Nature Reserve
The Upper Rock forms a nature reserve to which access is limited and an entrance fee charged. The reserve is managed by the Gibraltar Ornithological and Natural History Society. Approximately 40% of Gibraltar's land area falls within the nature reserve, created in 1993.
Flora and fauna
The flora and fauna of the Upper Rock Nature Reserve are of conservation interest and are protected by law. Within it is a range of animals and plants, but the highlights are the Barbary macaques (the famous Rock Apes), the Barbary partridges, and flowers such as Gibraltar's own chickweed, thyme and the Gibraltar candytuft.
The origin of the Apes is unknown but subject to many theories. They might may have originated from an escape of North African animals transported to Spain, or that the original Gibraltar macaques are a remnant of populations that are known to have spread throughout southern Europe during the Pliocene, up to 5.5 million years ago. Others say they were first brought from Morocco by British officers as pets, or by the Moors.
The Rock of Gibraltar, at the head of the Strait, is a prominent headland, which accumulates migrating birds during the passage periods. The vegetation on the Rock, unique in southern Iberia, provides a temporary home for many species of migratory birds that stop to rest and feed before continuing migration for their crossing over the sea and desert. In spring, they return to replenish before continuing their journeys to Western Europe, journeys which may take them as far as Greenland or Russia.
The Rock of Gibraltar is a monolithic promontory. It is a deeply eroded and highly faulted limb of an overturned fold. The sedimentary strata comprising the Rock of Gibraltar are overturned with the oldest strata overlying the youngest strata. These strata are the Catalan Bay Shale Formation (the youngest), Gibraltar Limestone, Little Bay Shale Formation (the eldest), and Dockyard Shale Formation (of unknown age). These strata are noticeably faulted and deformed..
The Catalan Bay Shale Formation consists predominately of shale. It also contains thick units composed of either brown calcareous sandstone; soft shaly sandstone interbedded with bluish-black limestone; and interlayered greenish-gray marls and dark gray cherts. The Catalan Bay Shale Formation contains unidentifiable echinoid spines and belemnite fragments and infrequent Early Jurassic (Middle Lias) ammonites.
The Gibraltar Limestone consists of greyish-white or pale-gray compact, and sometime finely crystalline, medium to thick bedded limestones and dolomites that locally contain chert seams. This formation comprises about three quarters of the Rock of Gibraltar. Geologists have found various poorly preserved and badly eroded and rolled marine fossils within it. The fossils found in the Gibraltar Limestone include various brachiopods; corals; echinoid fragments; gastropods (including ammonites); pelecypods; and stromatolites. These fossils indicate an Early Jurassic age (Lower Lias) for the deposition of the Gibraltar Limestone.
The Little Bay and Dockyard shale formations form a very minor part of the Rock of Gibraltar. The Little Bay Shale Formation consists of dark bluish-gray, unfossiliferous shale, which is interbedded with thin layers of grit, mudstone, and limestone. It predates the Gibraltar Limestone. The Dockyard Shale Formation is an undescribed varigated shale of unknown age that lies buried beneath the Gibraltar's dockyard and coastal protection structures.
These geological formations were deposited during the early part of the Jurassic Period some 175-200 million years ago, when the African tectonic plate collided tightly with the Eurasian plate. The Mediterranean became a lake that, over the course of time, dried up during the Messinian salinity crisis. The Atlantic Ocean then broke through the Strait of Gibraltar, and the resultant flooding created the Mediterranean Sea. The Rock forms part of the Betic Cordillera, a mountain range that dominates south-eastern Iberia.
Today, the Rock of Gibraltar forms a peninsula jutting out into the Strait of Gibraltar from the southern coast of Spain. The promontory is linked to the European continent by means of a sandy tombolo with of maximum elevation of 9 feet. To the north, the Rock rises vertically from sea level up to 1,350 feet at Rock Gun Battery. The Rock's highest point stands 1,398 feet above the strait at O'Hara's Battery.
The Rock's central peak, Signal Hill, stands at an elevation of 1,270 feet. The near-cliffs along the eastern side of the Rock drop down to a series of wind-blown sand slopes that date to the glaciations when sea levels were lower than today, and a sandy plain extended east from the base of the Rock. The western face, where the City of Gibraltar is located, is comparatively less steep.
Calcite, the mineral that makes up limestone, dissolves slowly in rainwater. Over time, this process can form caves. For this reason the Rock of Gibraltar contains over 100 caves. St Michael's Cave, found halfway up the western slope of the Rock, is the most prominent and is a popular tourist attraction.
Gorham's Cave is found near sea level on the steep eastern face of the Rock. Here archaeological excavations in the cave have found evidence that Neanderthals used it as long ago as 30,000 years. Plant and animal remains found in the cave and others nearby indicate that these Neanderthals had a highly varied diet.
- "Pillars of Hercules". The Gibraltar Museum. Archived from the original on 2007-07-20. http://web.archive.org/web/20070720172438/http://www.gib.gi/museum/phoenicians.htm. Retrieved 2008-01-14.
- Alternate Names or Name Variants for Gibraltar
- GONHS - A Guide to The Upper Rock Nature Reserve
- DNA solves mystery of Gibraltar's macaques
- Official Government of Gibraltar London Website
- Rose, E. P. F., and M. S. Rosenbaum, 1991, A Field Guide to the Geology of Gibraltar, The Gilbraltar Museum, Gibraltar. 192 pp.
- Earlham College - Physical Geology 2004 - The Rock of Gibraltar and Surroundings