the Acropolis of Athens - engineering geology study in the Acropolis area
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THE ACROPOLIS OF ATHENS - THE SOUTH SLOPE OF THE ACROPOLIS - PART 1 - THE THEATRE OF DIONYSOS
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Figure 6 Cross section of the Acropolis. Adapted from Higgins & Higgins (1976)
Figure 9 Geological map of the Acropolis and location of springs. Adapted from Higgins & Higgins (1976)
Figure 12 View of the Acropolis from the north west. The Clepsydra fountain is seen in the front. Source Hurwit (2004)
Abstract
The famous Acropolis in Athens is an ancient temple site located high up on a rocky cliff in the middle of Athens. Its turbulent history is long - in human life - span terms - and dates back to 6000 BC. It has been the focus of a myriad of texts written by all types of authors, but oddly enough, the rock that bears the site has scarcely been mentioned. This paper intends to fill that gap, to provide readers and visitors alike with a view of another much longer history, dating back to the Upper Cretaceous age,some 70 million years ago, when the rocks that underlie the rocky crest of the sacred hill were deposited in the delta of a mighty river. How much the geological composition and geological structure of the hill affects its human-related history, and why this particular hill has been – and for some, still is – considered sacred, might be a matter of intense debate. So first let us briefly address that glimpse of time. After all, a rock is only a rock, at least for us geologists. The famous Acropolis is an ancient temple site located high up on a rocky cliff in the middle of Athens. The hill is formed of a lowermost Upper Cretaceous (100 My) limestone resting on younger rocks of the Athens Schist Formation (72 My). Overthrusting, marked by the brecciated character of the lower part of the limestone, must have occurred during continental collision in the Upper Eocene orogenic phase; erosion and faulting produced the klippe that we can observe today. The contact between the lower Athens schist and the upper limestone has traditionally been a place of numerous springs and karstic caves. We describe the main characteristics and history of several springs and some caves used for worship.
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L'Acropole renommé est le site d'un ancien temple, localisé au sommet d'une falaise rocheuse, au centre d'Athènes. La colline est formée par un calcaire de la base du Crétacé supérieur (100 millions d'années) reposant sur des niveaux rocheux plus récents de la Formation des Schistes d'Athènes (72 millions d'années). Le chevauchement, caractérisé par le caractère bréchiforme de la partie inférieure des calcaires, a dû se produire pendant la collision continentale qui a eu lieu lors de la phase orogénique, à l'Eocène supérieur. Les processus d'érosion et de fracturation sont à l'origine de la klippe que nous observons aujourd'hui. Le contact entre les schistes inférieurs d'Athènes et les calcaires supérieurs fut traditionnellement à l'origine de nombreuses sources et cavités karstiques. Nous décrivons les caractéristiques principales et l'historique de plusieurs sources et de quelques cavités servant de lieux de culte.
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La famosa Acrópolis es un antiguo lugar de ubicación de templos, situado en una colina rocosa en el medio de Atenas. La colina está compuesta por una caliza de la base del Cretácico Superior (100 Ma) que descansa sobre rocas más jóvenes de la formación Esquistos de Atenas (72 Ma). El cabalgamiento, que se evidencia por el carácter brechoide de la parte inferior de la caliza, debe haberse producido durante la colisión continental de la fase orogénica del Eoceno Superior. La erosión y la fracturación han producido el klippe que observamos hoy. El contacto entre los Esquistos de Atenas inferiores y las calizas superiores ha sido ubicación tradicional de numerosos manantiales y cuevas kársticas. Se describen en este trabajo las características y la historia de varios de esos manantiales y cuevas utilizadas como lugares de culto
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The famous Acropolis in Athens is an ancient temple site located high up on a rocky cliff in the middle of Athens. Its turbulent history is long - in human life-span terms - and dates back to 6000 BC. It has been the focus of a myriad of texts written by all types of authors, but oddly enough, the rock that bears the site has scarcely been mentioned.
This paper intends to fill that gap, to provide readers and visitors alike with a view of another much longer history, dating back to the Upper Cretaceous age, some 70 million years ago, when the rocks that underlie the rocky crest of the sacred hill were deposited in the delta of a mighty river.
How much the geological composition and geological structure of the hill affects its human-related history, and why this particular hill has been – and for some, still is – considered sacred, might be a matter of intense debate. So fIrst let us briefly address that glimpse of time. After all, a rock is only a rock, at least for the geologists.
A brief history of a piece of rock
The Acropolis might have looked quite odd for our relatives 8,000 years ago, since the whole territory around it was more or less flat, except for this 70 m high, 300 m long and 150 m wide flat mound, along with the taller Likavitos to its north-west (Fig. 1) and Tourkovounia further north. There were probably some trees on the top of the Acropolis but not many, since the marble was probably outcropping exactly as it is today, forming high unassailable walls of rock. In fact the rock was a natural fortress because it was quite inaccessible from all sides (Fig. 2).
Figure 2 A probable look of the Acropolis from the south (left) and from the north (right) 8,000 years ago has been
This was probably the reason why the place was used to host a safe city, and this is why its name is acropolis, a Greek word meaning “city on the top” or “upper city”.
In Greek mythology, the first king and founder of Athens was Cecrops, quite a nice chap who is said to have unified all the tribes of the region. He apparently came from Egypt and wisely married Aglauro,
the daughter of Acteo, the King of Attica. Cecrops was also a knowledgeable man, as it is said that he taught the Athenians important things, such as marriage (before him, they probably lived promiscuously), reading and writing, and ceremonial burials; he also initiated the cult of Zeus. In fact, Acropolis is also named Cecropia in his honor. Cecrops was half man and half dragon, which in geological terms might means that he was a dinosaur-man...
It was Cecrops who gave the Athenians their name, as in the competition for the Acropolis he was the referee that decided that Athena came first over Poseidon; thus, Athena became the goddess patron of the city. Poseidon was not very happy with the result of the race so he decided to destroy the city with what today we would call a tsunami. Luckily enough he was not successful, apart from the fact that he probably managed to link the – at that time – island of Piraeus to land. In true prehistoric times
Piraeus was a rocky island consisting of the steep hill of Munichia (today Kastella) and was connected to the mainland by a low-lying stretch of land that was flooded with sea water most of the year, and used as a salt field whenever it dried up. Poseidon apparently also used his trident to try to make a salt water fountain on the top of the Acropolis, but he failed because Athena had planted an olive tree first. Maybe the salty isthmus of prehistoric Piraeus was the place that Poseidon´s trident hit, and so there seems to be again quite an interesting connection between myth and geology.
Another example of this relation is the case of Deucalion. In Greek mythology Deucalion was the equivalent of Noah in the Bible. He was the son of Prometheus (the creator of humankind), king of Phthia in Thessaly, and husband of Pyrrha; he was also the father of Hellen, the mythical ancestor of the Hellenic race. When Zeus, the king of the gods, resolved to destroy all humanity by a flood, Deucalion constructed an ark in which, according to one version, he and his wife rode out the flood and landed on Mount Parnassus. According to a story found first in the Roman poet Ovid’s Metamorphoses, Book I, upon offering a sacrifice and inquiring how to renew the human race, they were ordered to cast behind them the bones of their mother. The couple correctly interpreted this to mean they should throw behind them the stones of the hillside (“mother earth”), and they did so. Those stones thrown by Deucalion became men, while those thrown by Pyrrha became women. In early Greek versions Hermes told the couple directly to cast stones behind them. So the human race, according to Greek mythology, was destroyed by a flood and was then renewed from the stones thrown by Deucalion and Pyrrha, all of which is very geological.
If we go back to real history, many human inhabitants have made constructions in or on the Acropolis since the Mycenaean era, thanks to its the flat top table and the abundance of spring waters and caves. The place was deemed perfect for human habitation.
There is ample evidence of a Bronze Age Mycenaean palace or megaron on the hill, with a defensive Cyclopean 3.5 to 6 m thick massive 10 m high circuit wall around the whole mound, whose remains still exist.
The main gate was a ramp located to the southwest (where later the Erection was located) and there were steep, narrow flights of steps cut in the rock in the north. Geologically a noted earthquake before the 13th century BC caused a 35 m long fissure in the marbles near the northeastern edge of the Acropolis which sliced the marble down to the red schist underneath. The fracture probably helped in the development of a cave and a karstic spring, which was discovered in the second half of the 13th century BC during the works for the fortification of the Acropolis. A well called the Clepsydra was then dug here in the soft schist with an elaborated set of stairs, an invaluable source of fresh water for the city, but we will develop the topic of the underground water of Acropolis later on. To protect the spring a nine-gate wall, the Enneapylon, was built at the northwestern foot of the Acropolis.
What the archaeologists tell us now is that the Acropolis became a sacred place in the 6th century BC, when the northeastern side of the hill (near the current position of the Parthenon) hosted a temple dedicated to Athenia Polias, the Hekatompedon. Later in the same century, another temple known as the Archaios Naos or Old Temple was built in the Acropolis near the Hekatompedon, by the tyrant Peisistratos (527/528 BC). He also built a monumental entrance to the site of Propylaea. Peisistratos was not a dictator, as unfortunately we know them today, but a sort of constitutional leader (as even Aristotle wrote), because he was voted in as tyrant by the Athenian assembly in 561. He will be remembered by the Athenians because he instituted the famous Panathenaic Festival.
The Old Temple was destroyed by the Persians in their invasion of 480 BC, rebuilt in 454 BC, and finally probably succumbed to a fire in 405 BC. A huge new building was started before the invasion, which is known as the Older Parthenon or Pre-Parthenon.
To build this temple, the southern part of the Acropolis was leveled using blocks of limestone and earth, all of which was held in place by a wall. First they employed limestone from Piraeus although construction remained unfinished because of the invasion, and, when the Athenians defeated the Persians at the Battle of Marathon (490 BC), they decided to use marble instead.
After the war, the northern walls of the Acropolis were built using parts of the destroyed temples, and the devastated site was cleared of debris. The surroundings of the current Parthenon were again leveled to create an artificial plateau and many religious objects were buried ceremoniously by the Athenians in pits dug on the hill or in surrounding caves. This incredible archaeological deposit was discovered and excavated in 1885 and is called the “Persian debris”. The new walls were known as the Wall of Themistokles and the Wall of Kimon.
During the Golden Age of Athens (460 BC to 430 BC) most of the remains we see today of buildings and temples of Acropolis were constructed under the leadership of Pericles over almost half a century by workers who received a pay of 1 drachma a day, which apparently, according to Aristophanes, was decent pay for the daily subsistence of a family of three. The Parthenon, the Propylaia, the Erechtheion and the temple of Athena Nike, whose remains we can behold today, were built during this time.
Later, during the advent of Christianity, the monuments were converted into churches. All the structures were renamed and served as churches and cathedrals.
During the medieval period, some of the structures became residences or head-quarters for kings such as the Frankish or Turkish rulers. Wars, invasions and attacks destroyed important structures such as the Parthenon, leading to a tragic historical loss. It was only during the late 20th century that the Acropolis was properly excavated and the demolition of Ottoman buildings was decided upon.
Geology of the Acropolis
The geological history of Acropolis is much older than what we human beings can easily understand. The geological setting of the Athens area has been studied by several researchers since the middle 18th century (Lepsius, 1893; Kober, 1929; Marinos & Pet-rascheck, 1956; Tataris, 1967; Niedermayer,
1971a; Marinos et al., 1971; Trikkallinos, 1955; Paraskevaidis & Chorianopoulos, 1978). In spite of that, our knowledge about the lithostratigraphic structure of Athens is still incomplete.
But let us first review where the city of Athens is located. Athens lies in a great topographic basin surrounded by Mts Parnes, Aigaleos, Penteli and Hymettos (Fig. 1).
Figure 1 Geographic map of Athens showing its main physiographic features.
The basin was formed by the erosion of the soft Upper Cretaceous (72 My) Athens Schist, which outcrops or underlies the veneer of younger sediments in much of this area.
The hills in the eastern part of the Athens basin, such as Lykabettos, Areopagus, Acropolis and Philopappos, are all made of a lowermost Upper Cretaceous (100 My) limestone called locally “Tourkovounia Formation” (Karfakis & Loupasakis, 2006). All these hills form what in geology is called a "nappe" or "thrust sheet", that is, a sheet-like body of rock that has been moved several kilometers above a thrust fault from its original position (Gaïtanakis & Dietrich, 1992). In this case the oldest Upper Cretaceous limestone that was formed 30 My before the formation that now lies under the limestone, has been brought up and travelled from the south to finally end up resting on younger rocks of the Athens Schist Formation (72 My) (Figs. 3–5).
Figure 3 Geological map of Athens 1 50000.
Figure 4 Cross section NW-SE of the Acropolis. Gaïtanakis (1982)
Figure 5 Legend of the geological map and the cross section. Gaïtanakis (1982)
The time of emplacement of the Cenomanian limestones over the Pellagonian tectonic units is given by the minimum ages at the Athens schist. Over thrusting must have occurred during the Upper Eocene orogenic phase as result of continental collision.
After the Alpine compression ended, erosion and faulting produced a series of smaller Neogene basins in the main basin which were flooded by the sea and filled with transgressive or coastal facies with rocks such as sandstone, shale, clay and limestone. These rocks can still be seen exactly where they were deposited, except that recent tectonic movements have raised them above sea level. Many of the clay deposits were used by the ancient Athenian pottery industry, and some are still exploited today.
During the Quaternary much of the central and western parts of the basin were covered with a layer of alluvium up to 20 m thick as a result of infrequent floods in the recent past.
The Acropolis klippe
The Acropolis site has two main geological units from its lowermost part to the top of the rock (Fig. 6):
Figure 6 Cross section of the Acropolis. Adapted from Higgins & Higgins (1976)
1. Athens schist
2. Crest limestone
Both units are not only lithologicallly very different – a difference that has affected very much the geological and historical evolution of the rock – but also both have a dissimilar geological history. In fact the lower Athens schist is what is called an autochthonous terrain, that is, the rocks are located more or less where they were formed (in this case the same place where they were deposited), whilst the upper limestone, as mentioned above, is an alochthonous terrain, that is, it was formed in another place and is located where it is today due to extraordinary orogenic events. In geology, a structure like this is called a "klippe", that is, "the remnant portion of a nappe after erosion has removed connecting portions of the nappe". This process results in an outlier of exotic, often nearly horizontally translated strata overlying autochthonous strata.
And this is the most extraordinary and less known fact about the geology of Acropolis; the limestone rock has traveled from far away to finally stop where it is today, like a huge rock vessel that has run aground far inland after a terrible geological storm. In geological terms the limestone was thrust over the schist by the effect of the Alpine compression movements. In fact the limestone of Acropolis is 30 My older than the schist it lies upon.
The physical proof of this abrupt journey is reflected in the lowermost part of the limestone, in the contact with the schist, where the limestone shows a very distinct sheared texture. Instead of a normal limestone, what we see is a rock made up of fragments of limestone. This is called a cataclastic rock, that is, a rock that has been dragged along many kilometers not on the surface of the land, but down below the Earth at a certain temperature and pressure.
The faulting, granulation, and flowage of the original limestone produce a new rock called cataclastite (Fig. 7).
Figure 7 Outcrop of limestone cataclastite near the Propylea and on the southern slope of the Acropolis
After this process ended, erosion did the rest.
Athens schist
This formation has a very distinct red-dish color and is in general a so rock. In fact the huge open-air theatre of Dionysus Eleuthereus (with an original capacity of 17,000 spectators, built in the 4th century BC) and the smaller Odeion of Herodes Atticus (for 5,000 spectators, built in AD 161) are both located on the southern slope of the Acropolis, and were directly excavated in these rocks.
The Athens schist represents quite heterogeneous formations of low-grade metamorphic and relatively soft rocks (Fig. 8).
Figure 8 Contact between the cataclastite and the Athens schist on the southern slope of the Acropolis (above) and
The name of the stratigraphic formation was given because it extends over a great part of the ground of the city of Athens.
In the area of the Acropolis, the formation is composed of alternating beds of sericite sandstone, shales and phyllites, locally with intercalations and lenses of crystalline, usually microclastic, limestones. The Athens Schist bedrock shows remarkable weathering and intense folding, shearing and extensional faulting, which completed the structural “downgrading” of the rock mass.
Very complex folding, shearing and cataclastic phenomena can be observed within the flyschoid formation. Cataclastic deformation is certainly the most dominant feature in the more incompetent silty and sandy layers. Ductile deformation is weak in the slates. The occurrence of chlorite and crystallinity of illite/sericite transformation suggest burial temperatures around 200 °C. An overburden of 2 to 5 km rock pile on top of the Acropolis klippe is quite feasible. According to Marinos et al. (1971), the Athenian schist represents a flyshoid phase of delta-type deposit of the Upper Cretaceous (Maastrichtian, 70 My), that is, what we see today was once the talus of the delta of a huge river.
Acropolis limestone
The Acropolis limestone horst is fractured and block faulted by steeply inclined N-S, E-W and NW-SE trending faults. The cataclastic deformation increases towards the base as expressed by the occurrence of classical riedel•shear systems. The contact zone consists of several meters of strongly folded reddish and greyish cherts, fine grained siliceous limestones and slates.
An Upper Jurassic age for this formation is suggested by the occurrences of Radiolaria and Tintinidae. The slate-chert formation changes its deformational features rapidly along a few tens of meters towards east and west. As a result of displacement and heterogeneity of strain gradients, the schistosity (s-structure) has become uneven and shear banding (c-cisaillement) appeared. In the east, close to the Dionysos Theater, the same formation is developed as a homogenous “brecciated conglomerate” (Geitenekis & Dietrich, 1992).
According to most researchers (Megris, 1913; Kober, 1929; Marinos & Petrasceck, 1956; Trikallinos, 1955; Niedermayer, 1971 and others) the upper calcareous horizons overthrust the marly horizon and the hilltops of the city of Athens were deposited in form of big olistoliths. According to that interpretation, the breccio–conglomerate beds located along the base of the limestones are tectonic mylonites.
Hydrogeology of Acropolis
It is quite clear that the first inhabitants of the Acropolis selected this place for their residence due to the natural protection of the rock, but also because there were many natural springs, with the Clepsydra spring being its most famous representative. Thus, fresh water was another important clue for the historical development of the site (Chiotis & Chioti, 2012).
The contact between the Athens schist and the overlying upper limestone is a typical place where geologists might expect to find springs. The reason for that is that limestone can easily become a good groundwater container via its fractures and its caves, whilst the schist is a relatively impermeable formation due to its clayey content. The result of this combination is that the water often flows in the contact of both formations (Figs. 9, 10)
Figure 9 Geological map of the Acropolis and location of springs. Adapted from Higgins & Higgins (1976)
Figure 10 Aerial view of Acropolis. Google Earth 2013
in what can be considered a hanging aquifer, discharging regularly by three small springs with a discharge of 0.5 to 1 l per minute in the dry season, which can increase considerably during rainfalls.
The quantity of penetrating water amounts to 4,500 m3 per year (Andronopoulos & Koukis, 1976).
Even today, we can see the contact in the growth of fig trees and in karstic formations that provide evidence of ancient water flows (Fig. 11).
Figure 11 Old karstic conduction on the Acropolis limestone
The HYDRIA Project ...(http://www.hydriaproject.net/en/cases/athens/acropolis_hill/asklipios.html)
, a multinational project on the history of the use of water, has made several case studies from Mediterranean countries, including the Acropolis springs. A summary of its findings follows.
Northern springs
On the northern slope of the Acropolis, inside the cave of Ersis (until recently attributed to the nymph Aglauros), an impressive structure exists for a spring that was probably discovered during the fortification works of the Acropolis (Pelargikon or Pelasgikon wall, second half of 13th century BC) for the protection against imminent invasion by the Dorians.
The spring construction, in use only for a short time during the Mycenaean period, is believed to be one of the first technical works to ensure water supply to the city. Mycenaean pottery found in it, dating from the second half of the 13th century BC and not later, indicates that the period of use was no longer than 30-40 years. A landslide or earthquake must have blocked it.
The entrance to the cave is at the level of the Parthenon, west of the Arrhephorion, a small square building where young women (Arrhephoroi) used to weave the mantle/veil of the goddess (Athena) for the Panathenaic festival and other rituals.
The cave is an impressive, almost vertical fissure, 35 m deep, with a series of stairways. In the upper part the rock was carved in order to support wooden steps; while in the lower part the stairways were made using large schist slabs placed on rubble, which was supported by wooden beams. The stairway ended at the boundary between the upper layer of limestone rock and the underlying layer of marl rock. In this lower part of the cave there was a well, 9 m deep, that provided access to an underground vein of water. The diameter of the well was ~ 2 m at the surface and 4 m near the bottom.
The spring ceased to be in use, as its lower part was covered with soil, probably due to an earthquake or landslide. However, the upper part of the cave remained intact and was used during antiquity, and in sub-sequent periods, as a secret passage, since it has a second exit to the north slope of the rock. Actually, this passage is linked to a heroic moment in recent Greek history.
During the Nazi occupation in 1941 two students,
Manolis Glezos and Apostolos Santas, used this passage to reach the Acropolis and take down the Nazi flag.
Clepsydra
Clepsydra, the most important fountain and spring of the Acropolis, is located inside a cave on the northwest of the Acropolis at the point where the ancient streets Pana-thenaic Way and Peripatos met (Fig. 12). Its name gives us an important clue about the nature of this spring, since the word κλεψύδρα in Greek means “stolen water” and was given to the spring because its water appeared and disappeared from time to time.This is what we would expect from a karstic spring whose main source is the infiltration of rainwater in the limestone.Although the cave spring was rediscov-ered in the second half of the 13th century BC during the works for the fortication of the Acropolis, it is well known that during the Neolithic period, the inhabitants of Athens were aware of the underground water vein in the area. In fact they opened 22 wells (3–5 m deep) to exploit it. The area was originally named after the nymph Empedo, who was related to water.
During the cited fortification works it was ensured that this cave spring, along with the Asklepieion spring house on the other side of the Acropolis, were located inside the walls, as these would provide protec-tion and easy access to the valuable resource within the walls.
Kimon, who ruled Athens in the period 470–460 BC, transformed the spring into a fountain, including rectangular 56 m2 flooring and a deep reservoir inside the cave with a staircase for access. There were frequent rock falls and landslide aect-ing the spring, but particularly in the 10th century BC a rock fall severely affected the fountain. Protection works were then car-ried out in the fountain against potential collapse of the overlying rock using wooden braces. Landslides in the 1st century AD compelled the Athenians to change the entrance to the fountain, but this entrance was also blocked by yet another landslide in the late 2nd century AD, depriving access to the spring from the Panathenaic Way.
Then a well was opened in order to draw water through the fallen rock and above it a solid vaulted construction was created for protection. From this point an ascending vaulted corridor (70 steps) led to the foot of the bastion below the Propylaia, this being the only way to access the spring-house. During the Christian era the church of St. Apostoloi was built in the fountain.
The Clepsydra spring was used through-out the Byzantine period (4th–15th century AD) and was again repaired during the Frankish occupation (mid-13th century). The spring was completely abandoned during the Turkish occupation until it was rediscovered in 1822 by the Greek archae-ologist Kyriakos Pittakis.
Southern springs
On the southern slope of the Acropolis stand the remains of the temple of Asklepios, god of healing for Ancient Greeks. To the west of the Ionic stoa, one of the auxiliary buildings of the temple, a small fountain house has been discovered, dating from the end of the 6th century BC. e width of the fountain house must have been about 3 m internally and therefore about 4bm exter-nally. It is believed that the entrance to the fountain was through a kind of porch, which was demolished in the 4th century BC, when the well was covered with earth and was no longer used.
In the early Christian period, around AD 450, the temple of Asklepios was demolished to be replaced with a Chris-tian temple that was built using the same building material. Interestingly this new church was devoted to the saints Anar-gyroi (two brothers who were doctors), considered also saints of healing, and the spring was used for its “holy” water. This is a common phenomenon in the transition from idolatry to Christianity in Greece, that the ancient Gods are replaced with Chris-tian saints who are considered “protectors” of the same characteristic, i.e. health, travel, family, crops, etc.
Caves of Acropolis
The cave of Clepsydra has already been mentioned above, but there are other caves in the slopes of the Acropolis worth men-tioning.
Apollo’s altar in the cave: near Clepsydra is the altar-cave of Apollo. Aer the elec-tion of the nine archons of Athens, it was usual for them to take an oath in the altar of Apollo Patroos and then to come here to take a second vow. Among other things they vowed that if they did not govern correctly or if they became embezzlers of public property they would create a golden statue of Apollo Pythiou-Patroou inside the altar. When their service was finished they offered a marble plaque with sculpted laurel and myrtle wreaths in memory of their successful service for the public good. An abundance of such plaques were found inside the cave and the area around it.
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Cave of Zeus Astrapaios: right next to the cave of Apollo there is a second, more impressive cave, dedicated to Zeus. Every spring the Pythaists waited inside the cave for a bolt of lightning, a sign from Zeus appearing on the top of Arma hill in Par-nitha Mountain, in order to begin their course towards Delphi. e Pythaists were chosen Athenian citizens who represented the city during the Delphic celebrations of the Pythians. When the Pythaists returned from the Delphic altar they brought back fire, “new light”, to purify the altars of Athens. Recent geological investigations have started a controversy on whether gas emissions from a geologic chasm in the earth could have inspired the Delphic Oracle to “connect with the divine”. (Pic-cardi et al., 2008; Spiller et al., 2008); this is another interesting relation of Ancient Greece mythology and geology.
Cave of Pan: next to the cave of Zeus Astrapaios and a bit to the east another small cave was found, dedicated to the god of woods and shepherds, Pan. e worship of Pan came to Athens late, after the victory of Marathon in 490 BC. Tradition has it, according to the sayings of Herodotus, that Pan appeared in the battlefield of Marathon, spread terror to the Persians and helped the Athenians win even though they were fewer. The Athenians, grateful for this victory, decided to honour Pan here and also organised a torchlight procession. They carved small niches into the rock and placed their oblations, statues, flutes and even deli-cacies there. The cave of Pan is known to us from the work of Aristophanes, Lysistrati. During the Christian years the sacred cave of the goat-legged god became Saint Athanasios’ church.
Mycenaean Drinking Fountain - Ersis’s Cave: an impressive cave is situated a bit to the east and is attributed to Aglavros, the daughter of Cecrops. Recent research has shown that this was the altar of Ersis. This cave is in fact a drinking fountain, formed when the Mycenaeans surrounded the Acropolis with walls during the second half of the 13th century BC. Its entrance was found on the Acropolis near the Ere-chtheum. The Mycenaean drinking fountain was barely used (for only 30 years), as is obvious from the vases that were found.
It is probable that a landslide covered the fountain and as a result its bottom section was forgotten, while the upper part was used as a secret exit of the Acropolis.
The altar of Aphrodite in the garden: here, the worship of Aphrodite replaced that of the Mycenaean goddess with the doves worshipped as the goddess of fertility near the Mycenaean entrances of the Acropolis. In this shrine of the goddess of love and fertility a group of Arrifores performed a ceremony one summer evening, a revival of an old agricultural custom whose purpose was to reinforce the fertility of the ground. Here also on the ancient worshippers placed their oblations in carved niches in the rock of the shrine. At the same location many dedicative signs for Aphrodite and love were found.
Moving on, towards the northeastern side of the Acropolis we can see the neighbourhood called Anafiotika, outside the walls. Small white-washed houses with narrow alleys remind us of the villages of the Cycladic islands. This picturesque quarter was built in the middle of the 19th century by craftsmen from Anafi Island.
Conclusions
The sacred Acropolis hill, along with its famous monuments, has a long human-related story linked to its obvious morpho-logical and geological features such as its hydrogeology and its karstic caves, and the mighty consortium also has a close relation with Greek mythology.
But the rock, aside from its incredible historical antecedents, also hides a spectacular geological secret: the limestone underlying the temples – dated from the Upper Cretaceous (more than 100 my ago) – was initially a soft mud sediment, deposited 120 km south of its current location. Later on the calcareous mud consolidated and transformed into a limestone by diagenetic processes. Then a colossal but extremely slow continental collision of the Alpine orogeny during the Upper Eocene moved the recently created rock over the overlying schist of the Athens Schist Formation by a process called thrusting and brought the limestone to where it is today. Such geological structure in geological terms is called a klippe. The evidence of that long journey can be observed in a special type or rock called cataclastite in the foot of the hill. Erosion did the rest and left the lime-stone hill isolated and surrounded by the younger schist, as found by the first dwellers of Athens.
Sacred land and geology meet in the rocky heights of Athens. Understanding both features is probably the door to sustainable use of the archaeological site.
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https://www.researchgate.net/publication/269076024_The_geology_of_the_Acropolis_Athens_Greece
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( English ) the StatCounter was installed on 2018-06-19, 17:30 p.m. GMT
( Greek ) ( Ελληνικά ) Ο μετρητής εγκαταστάθηκε την 19-06-2018 19:30 μ.μ. ώρα Ελλάδας
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