Eurotas River
Encyclopedia
The Eurotas or Evrotas (Greek: Ευρώτας) is the main river of Laconia
Laconia
Laconia , also known as Lacedaemonia, is one of the regional units of Greece. It is part of the region of Peloponnese. It is situated in the southeastern part of the Peloponnese peninsula. Its administrative capital is Sparti...

 prefecture
Prefectures of Greece
During the first administrative division of independent Greece in 1833–1836 and then again from 1845 until their abolition with the Kallikratis reform in 2010, the prefectures were the country's main administrative unit...

 and one of the major rivers of the Peloponnese
Peloponnese
The Peloponnese, Peloponnesos or Peloponnesus , is a large peninsula , located in a region of southern Greece, forming the part of the country south of the Gulf of Corinth...

, in Greece
Greece
Greece , officially the Hellenic Republic , and historically Hellas or the Republic of Greece in English, is a country in southeastern Europe....

. The river's springs are located just northwest of the border between Laconia and the prefecture
Prefectures of Greece
During the first administrative division of independent Greece in 1833–1836 and then again from 1845 until their abolition with the Kallikratis reform in 2010, the prefectures were the country's main administrative unit...

 of Arcadia
Arcadia
Arcadia is one of the regional units of Greece. It is part of the administrative region of Peloponnese. It is situated in the central and eastern part of the Peloponnese peninsula. It takes its name from the mythological character Arcas. In Greek mythology, it was the home of the god Pan...

, at Skortsinos
Skortsinos
Skortsinos is a Greek village in westcentral Arcadia, close to its southern border to Laconia. Agriakona had a 2001 population of 83 for the village.-Distances:...

. The river is also fed by underwater springs at Pellana
Pellana
Pellana , was a city of Laconia, on the Eurotas river, and on the road from Sparta to Arcadia....

 and by tributaries coursing down from Mt. Taygetos and Mt. Parnon
Parnon
Parnon or Parnonas or Malevo is a mountain range, or massif, on the east of the Laconian plain and the Evrotas valley. It is visible from Athens above the top of the Argive mountains. The western part is in the Laconia prefecture and the northeastern part is in the Arcadia prefecture. The Parnon...

, which flank the Eurotas valley to the west and east, respectively. The river is 82 kilometres (51 mi) long, flowing in a north-south direction and emptying into the Laconian Gulf
Laconian Gulf
The Laconian Gulf , is a gulf in the south-eastern Peloponnese, in Greece. It is the southernmost gulf in Greece and the largest in the Peloponnese. In the shape of an inverted "U", it is approximately 58 km wide east-west, and 44 km long north-south...

.

Etymology

The classical Eurotas was changed to Iri in the Middle Ages and only changed back to Eurotas in recent times. Eurotas, however, is not the most ancient known name of the river. It does not appear in the works of Homer
Homer
In the Western classical tradition Homer , is the author of the Iliad and the Odyssey, and is revered as the greatest ancient Greek epic poet. These epics lie at the beginning of the Western canon of literature, and have had an enormous influence on the history of literature.When he lived is...

, which purport to recount the stories and geography of Mycenaean Greece. In that legendary time, the Dorians are not known to have been present in the Eurotas Valley. At some time prior to being called Eurotas, the river was the Bomycas and the Himeras.

One etymology derives the word Eurōtas from the ancient Greek
Ancient Greek
Ancient Greek is the stage of the Greek language in the periods spanning the times c. 9th–6th centuries BC, , c. 5th–4th centuries BC , and the c. 3rd century BC – 6th century AD of ancient Greece and the ancient world; being predated in the 2nd millennium BC by Mycenaean Greek...

 eurōs, "mold." The adjective, eurōeis, "moldy," is genuinely ancient, used as an epithet of Hades
Hades
Hades , Hadēs, originally , Haidēs or , Aidēs , meaning "the unseen") was the ancient Greek god of the underworld. The genitive , Haidou, was an elision to denote locality: "[the house/dominion] of Hades". Eventually, the nominative came to designate the abode of the dead.In Greek mythology, Hades...

 in Homer. It is, however in the Ionic dialect.

Source

The source of the Eurotas River; that is, the highest elevation of its continuous flow, is a surface spring
Spring (hydrosphere)
A spring—also known as a rising or resurgence—is a component of the hydrosphere. Specifically, it is any natural situation where water flows to the surface of the earth from underground...

 called Pēges Eurōta, "Evrotas Springs," located in the village of Skortsinou by the side of the road ascending from Kyparissi
Kyparissi
Kyparissi is a small village along the north east coast of Laconia, Greece. It is part of the municipal unit of Zarakas....

 to Skortsinos
Skortsinos
Skortsinos is a Greek village in westcentral Arcadia, close to its southern border to Laconia. Agriakona had a 2001 population of 83 for the village.-Distances:...

 in the prefecture of Arcadia
Arcadia
Arcadia is one of the regional units of Greece. It is part of the administrative region of Peloponnese. It is situated in the central and eastern part of the Peloponnese peninsula. It takes its name from the mythological character Arcas. In Greek mythology, it was the home of the god Pan...

. The spring is an outlet of an aquifer
Aquifer
An aquifer is a wet underground layer of water-bearing permeable rock or unconsolidated materials from which groundwater can be usefully extracted using a water well. The study of water flow in aquifers and the characterization of aquifers is called hydrogeology...

 located in the adjacent limestone
Limestone
Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....

 ridge at a locale called Kephalari. The ridge, a karst
KARST
Kilometer-square Area Radio Synthesis Telescope is a Chinese telescope project to which FAST is a forerunner. KARST is a set of large spherical reflectors on karst landforms, which are bowlshaped limestone sinkholes named after the Kras region in Slovenia and Northern Italy. It will consist of...

, is not part of the Taygetus
Taygetus
Mount Taygetus, Taugetus, or Taigetus is a mountain range in the Peloponnese peninsula in Southern Greece. The name is one of the oldest recorded in Europe, appearing in the Odyssey. In classical mythology, it was associated with the nymph Taygete...

 Massif, but, like the other mountains of Arcadia, is a nappe raised by the compressional forces on the Hellenic Plate by the subduction of Africa. The spring is also called Logaras Spring.

Logaras Spring supplies an anciently constructed catchment basin about the size of a pond, though sometimes called a lake, which exits both to irrigation channels and to the Alpheios Potamos, a stream. The flow is copious except in times of drought. A recent study measured the outflow through the catchment exit every 15 days for 540 days in 2006-2007. It recorded a maximum of 1748 cubic m per hour and a minimum of 310.5 cubic m per hour. From the catchment at an altitude of 430 m (1,410.8 ft) part of the water flows into the Alpheios, a stream of the same name as the Alfeios River of Arcadia. The Laconian stream enters the upper Eurotas.

The two rivers are unconnected in any way above ground or below it. The identity of names comes from an ancient geologic misunderstanding that the Eurotas and the Alfeios were connected underground, which deceived even Pausanias, one of the best ancient geographers. He believed they had the same source but the outflow stream disappeared into a chasm only to emerge at different locations as different streams. In the most exaggerated form of the myth, the Alfeios continues under the Mediterranean to Sicily or elsewhere.

Main stream

The river today is hydromorphologically far from its natural state. The main problem is anthropogenic abstraction of water from the shallow aquifer through which it flows by many methods. The valley contains about 7000 wells. Water is removed more directly by irrigation ditches, weirs and pumping stations. As a consequence of these activities, the river is intermittent; large sections are typically dry of surface water, even though water still flows in the aquifers. Flash flooding is a problem. As flood control measures the riverbed in places has been widened, straightened and the vegetation removed from its sides. The lower river runs between dikes in a long, straight course.

Tributaries

Most of the numerous tributaries of the Eurotas are right-bank, feeding the shallow aquifer. They are, however, intermittent and ephemeral. The major ones have cut deep ravines into the Taygetus Massif. The few left-bank tributaries, receiving waters from the deep aquifer, are more substantial, but still intermittent.

The classical Oineus was changed to the Kelefina in the Middle Ages and not restored to its ancient name until recent times. The current Magoulitsa was formerly the Trypiotiko.

Delta

The rich alluvial soil through which the final 10 km of the Eurotas flows was not there in antiquity. The Eurotas has aggraded the innermost bay of the gulf. The old coastline can be approximated by a line on the periphery of the plain of Elos
Elos
Elos is a village and a former municipality in Laconia, Peloponnese, Greece. Since the 2011 local government reform it is part of the municipality Evrotas, of which it is a municipal unit. It was called Durali until 1912. The population of the village is 920 people . The municipal unit has 6,452...

 marking the border within which prehistoric archaeological sites are not found. The line on the west follows the Skalas-Gytheou road to Skala, the Skalas-Molaon road to Vlachiotis, southeast along the edge of the rising terrain to Asteri and south from there to the coast. Due to changes in sea level, some land on the flanks of the gulf has been drowned.

The current communities of Elos, Leimonas and Agioi Taksiarches have been constructed on aggraded land. As Pausanias mentions that Elos was a port city, the current Elos cannot be it. Skala
Skala, Laconia
Skala is a town and a former municipality in Laconia, Peloponnese, Greece. Since the 2011 local government reform it is part of the municipality Evrotas, of which it is the seat and a municipal unit. Population 5,902 . Skala is known for organic food production and the organic wholesaler Stavros...

, on the other hand, means "place of embarkation." The location of the ancient port, however, is not yet known for certain.

Legendary prehellenic tribe

In Greek legend, the human ancestor of all the peoples that inhabited the Eurotas Valley was Lelex
Lelex
In Greek mythology, Lelex was a King of Laconia. He was married to the Naiad nymph, Cleochareia. He had several sons, including Myles, Polycaon, Pterelaus, and Cteson. The parentage of Lelex is variously stated...

, eponym
Eponym
An eponym is the name of a person or thing, whether real or fictitious, after which a particular place, tribe, era, discovery, or other item is named or thought to be named...

ous king of the Leleges
Leleges
The Leleges were one of the aboriginal peoples of southwest Anatolia , who were already there when the Indo-European Hellenes emerged. The distinction between the Leleges and the Carians is unclear. According to Homer the Leleges were a distinct Anatolian tribe Homer...

, one of the peoples of the eastern Aegean whom the classical writers saw as autochthonous; that is, indigenous and pre-Hellenic. His son or grandson was Eurotas
Eurotas
In Greek mythology, Eurotas was a son of Myles and grandson of Lelex, eponymous ancestor of the Leleges, the pre-Greek people residing, in the myth, in the Eurotas Valley. He had no male heir, but he did have a daughter, Sparta. Eurotas bequeathed the kingdom to her husband, Lacedaemon, the son of...

, the last of the line. The latter had a daughter, Sparta, but no sons. An outsider married her, Lacedaemon. Although he named the state Sparta after her, his name is now known to have most likely been the name of the Mycenaean state.

Mycenaean
Mycenaean Greece
Mycenaean Greece was a cultural period of Bronze Age Greece taking its name from the archaeological site of Mycenae in northeastern Argolis, in the Peloponnese of southern Greece. Athens, Pylos, Thebes, and Tiryns are also important Mycenaean sites...

, or Late Bronze Age Greece is generally conceded to be Achaean Greek on the evidence of the Linear B
Linear B
Linear B is a syllabic script that was used for writing Mycenaean Greek, an early form of Greek. It pre-dated the Greek alphabet by several centuries and seems to have died out with the fall of Mycenaean civilization...

 and Hittite documents. If any Dorians were present they were not in any capacity overtly recorded by the surviving administrative records. If the Leleges
Leleges
The Leleges were one of the aboriginal peoples of southwest Anatolia , who were already there when the Indo-European Hellenes emerged. The distinction between the Leleges and the Carians is unclear. According to Homer the Leleges were a distinct Anatolian tribe Homer...

 really were in the Eurotas Valley, the time of their ascendance would have been before Mycenaean times, as the latter were Greek in Greece. Until the later 20th century, evidence of earlier occupation in the valley seemed to be in deficit.

Beginning in 1968 the University of Cambridge
University of Cambridge
The University of Cambridge is a public research university located in Cambridge, United Kingdom. It is the second-oldest university in both the United Kingdom and the English-speaking world , and the seventh-oldest globally...

 began a survey by underwater archaeology of a drowned town between Pounta on the mainland and Elafonisos
Elafonisos
Elafonisos is a small Greek island between the Peloponnese and Kythira. It lies off the coast of Cape Malea and Vatika. The area of the island is 19 km²....

 Island on the eastern side of the Laconian Gulf
Laconian Gulf
The Laconian Gulf , is a gulf in the south-eastern Peloponnese, in Greece. It is the southernmost gulf in Greece and the largest in the Peloponnese. In the shape of an inverted "U", it is approximately 58 km wide east-west, and 44 km long north-south...

. The town extended over the entire drowned isthmus from 60 rock-cut tombs on the Pounta shore (a beach) to the remains of walls on Pavlopetri
Pavlopetri
The city of Pavlopetri, underwater off the coast of southern Laconia in Greece, is about 5000 years old, and is the oldest submerged archeological town site. It is unique in having an almost complete town plan, including streets, buildings, and tombs...

 Island off Elafonisos. A subsequent survey in 2009 discovered even earlier parts of the town and recovered additional pottery. A chronological study was done on "442 ceramic items, an iron nail and an obsidian chip." More research on the site is planned.

The town was apparently continuously occupied from the Final Neolithic to Byzantine times when it was drowned, perhaps by an earthquake. Neolithic ceramics were only 3% of the 444 items. The town was mainly Early Bronze Age, which had 40%. The Early Helladic pottery is "standard ... some showing close links with the Cyclades
Cyclades
The Cyclades is a Greek island group in the Aegean Sea, south-east of the mainland of Greece; and a former administrative prefecture of Greece. They are one of the island groups which constitute the Aegean archipelago. The name refers to the islands around the sacred island of Delos...

, western Crete
Crete
Crete is the largest and most populous of the Greek islands, the fifth largest island in the Mediterranean Sea, and one of the thirteen administrative regions of Greece. It forms a significant part of the economy and cultural heritage of Greece while retaining its own local cultural traits...

 and the northeastern Aegean." The "15% Middle Bronze Age" is represented by Middle Helladic and Middle Minoan. This archaeological scenario is not incompatible with the Aegean distribution of the Leleges, although it is not possible to say who the Early and Middle Bronze Age inhabitants were.

The Late Bronze Age had 25% of the items. Classical and Byzantine items were minimal, indicating a probable near abandonment of the city at the end of the Late Bronze Age.

Mycenaean Lacedaemon

Archaeology has a more complete story to tell. On the left bank of the Eurotas, across from Sparta, is a ridge on which sits a temple called the Menelaon. In the 20th century a survey by the British School of Archaeology
British School at Athens
The British School at Athens is one of the 17 Foreign Archaeological Institutes in Athens, Greece.-General information:The School was founded in 1886 as the fourth such institution in Greece...

 revealed that the entire ridge, located in the municipal unit of Therapnes
Therapnes
Therapnes , in ancient times Therapne , is a Municipal Unit of the municipality of Sparti within the Regional Unit of Lakonia in the Region of Peloponnēsos, one of 7 Regions into which the Hellenic Republic has been divided by the Kallikratis plan, authorized by Law 3852, Issue 1 of 7 June 2010...

, ancient Therapnē, had been covered by a walled Mycenaean
Mycenaean
Mycenaean may refer to:* Something from or belonging to the ancient town of Mycenae in Peloponnese in Greece* Mycenaean Greece, the Greek-speaking regions of the Aegean Sea as of the Late Bronze Age* Mycenaean language, an ancient form of Greek...

 town, dated to the Late Bronze Age by the LH3 pottery with some MH pottery in "pockets in the bedrock." The archaeologists analyzing the site recognized a building Period I, dated LH2B to LH3A1, the latter being brought to and end about 1425 BC by a severe earthquake. Remains of a mansion with Minoan
Minoan
Minoan may refer to the following:*The Minoan civilization**The Eteocretan language**The script known as Linear A**Minoan pottery*Minoa, name of several bronze-age settlements in the Aegean....

 pottery date from Period I.

During Period IA, the hill settlement was rebuilt. The structures included kilns for smelting bronze. In Period II, dated to LH3A1, a villa-type structure was built of a terrace formed from previous building material further down to the south. It was probably two-story, megaron
Megaron
The megaron is the great hall of the Grecian palace complexes. It was a rectangular hall, fronted by an open, two-columned porch, and a more or less central, open hearth vented though an oculus in the roof above it and surrounded by four columns. It is the architectural predecessor of the...

-type, with "less substantial walls" but "a massive foundation for what could be a defense tower." It was connected to the top by stairs. Period III, LH3A2-LH3B2, begins with 150 years of apparent abandonment and then a limited reconstruction of a one-story structure on the terrace. The staircase was blocked. The entire ridge was intensely occupied leaving a profusion of Mycenaean pottery. At the end of LH3B2 is a destruction level. The villa was burned. Two burials in rubble nearby are of persons who appear to have died violently. Occupation of the hill went on through the Greek Dark Age, reducing to a shrine in the Archaic and Classical Periods, the Menelaon. Dedications to Menelaus
Menelaus
Menelaus may refer to;*Menelaus, one of the two most known Atrides, a king of Sparta and son of Atreus and Aerope*Menelaus on the Moon, named after Menelaus of Alexandria.*Menelaus , brother of Ptolemy I Soter...

 and Helen are found in its vicinity starting the Archaic Period.

The excavators concluded that in the "later fifteenth century" (BC) the ridge was "the principal settlement site in Laconia." The shrine and its dedications identify it as the site of Homeric Sparta, capital of a ruling couple believed by the population of the Archaic Period to have been Menelaos and Helen.

Classical Sparta

The ancient city of Sparta
Sparta
Sparta or Lacedaemon, was a prominent city-state in ancient Greece, situated on the banks of the River Eurotas in Laconia, in south-eastern Peloponnese. It emerged as a political entity around the 10th century BC, when the invading Dorians subjugated the local, non-Dorian population. From c...

 was built on the west bank of the Eurotas about half-way down the valley. The Spartans had little use for the left bank of the river: only one permanent bridge crossed to it at Therapne
Therapnes
Therapnes , in ancient times Therapne , is a Municipal Unit of the municipality of Sparti within the Regional Unit of Lakonia in the Region of Peloponnēsos, one of 7 Regions into which the Hellenic Republic has been divided by the Kallikratis plan, authorized by Law 3852, Issue 1 of 7 June 2010...

 just south of the city. The main traffic was southward to the port of Gytheio
Gytheio
Gytheio , the ancient Gythium or Gytheion , is a town and a former municipality in Laconia, Peloponnese, Greece. Since the 2011 local government reform it is part of the municipality East Mani, of which it is a municipal unit. It was the seaport of Sparta, some 40 km north...

, which was the most convenient outlet. All others involved a trek over mountains.

Post-classical Laconia

Modern Laconia is a political subdivision of Greece covering the Eurotas Valley, the massifs on either side, the two headlands and the enclosed Laconian Gulf
Laconian Gulf
The Laconian Gulf , is a gulf in the south-eastern Peloponnese, in Greece. It is the southernmost gulf in Greece and the largest in the Peloponnese. In the shape of an inverted "U", it is approximately 58 km wide east-west, and 44 km long north-south...

 with its coastal islands. Its borders have been stable for centuries. Formerly one of 51 prefectures (nomoi) of Greece it became one of five Regional Units (Perifereiskai Enotētai) within the Peloponnese Region (one of 13 periferaiai of Greece) during the reforms of 2010. Before the reforms Laconia contained 22 municipalities, which also have been stable for centuries, some based on ancient villages. These were reduced to municipal units and reorganized under five municipalities (demoi): East Mani
East Mani
East Mani is a municipality in Laconia, Peloponnese, Greece. Its seat of administration is the town Gytheio. The municipality is located in the eastern part of the Mani Peninsula...

, Elafonisos
Elafonisos
Elafonisos is a small Greek island between the Peloponnese and Kythira. It lies off the coast of Cape Malea and Vatika. The area of the island is 19 km²....

, Evrotas, Monemvasia
Monemvasia
Monemvasia is a town and a municipality in Laconia, Greece. The town is located on a small peninsula off the east coast of the Peloponnese. The peninsula is linked to the mainland by a short causeway 200m in length. Its area consists mostly of a large plateau some 100 metres above sea level, up to...

 and Sparti. The seat of Sparti is still the city of Sparti. It dominated and still does dominate the valley from its central position. However, the rich-soil plain is entirely divided into villages that practice agriculture
Agriculture
Agriculture is the cultivation of animals, plants, fungi and other life forms for food, fiber, and other products used to sustain life. Agriculture was the key implement in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that nurtured the...

, viticulture
Viticulture
Viticulture is the science, production and study of grapes which deals with the series of events that occur in the vineyard. When the grapes are used for winemaking, it is also known as viniculture...

 and arboriculture
Arboriculture
Arboriculture is the cultivation, management, and study of individual trees, shrubs, vines, and other perennial woody plants. It is both a practice and a science....

 intensely.

The main roads from Sparti form a branching network leading out radially from the city to connect other cities and towns in the valley. A web of secondary roads fills in the spaces between the main roads.

Ecology

In modern times, much of the river water is used for irrigation, with the result that the Eurotas is almost dry during the summer months. The waters of the Eurotas are used to irrigate mainly citrus crops, for which Laconia is famous. The plain of Elos
Elos
Elos is a village and a former municipality in Laconia, Peloponnese, Greece. Since the 2011 local government reform it is part of the municipality Evrotas, of which it is a municipal unit. It was called Durali until 1912. The population of the village is 920 people . The municipal unit has 6,452...

 near the river's mouth is particularly fertile farmland.

In the winter months, the Eurotas is prone to flooding. On November 24, 2005, a low-pressure system caused heavy floods, damaging buildings and stranded automobiles in the streets. Crops including the valley's famous orange and olive groves were damaged. The floods affected many villages along the valley as well as the town of Gytheio; 170 square kilometre of land was ruined.

Currently the nitrate waste from fertilizer is polluting the river, which has diminished flow because of the irrigational demands on it.

Geomorphology

The Eurotas River occupies the floor of a rift valley
Rift valley
A rift valley is a linear-shaped lowland between highlands or mountain ranges created by the action of a geologic rift or fault. This action is manifest as crustal extension, a spreading apart of the surface which is subsequently further deepened by the forces of erosion...

 or graben
Graben
In geology, a graben is a depressed block of land bordered by parallel faults. Graben is German for ditch. Graben is used for both the singular and plural....

 created by extensional forces acting over the Hellenic Plate in a northeast-southwest direction. The corresponding fault-block mountain
Fault-block mountain
Fault-block landforms are formed when large areas of bedrock are widely broken up by faults creating large vertical displacements of continental crust....

s are the Taygetus
Taygetus
Mount Taygetus, Taugetus, or Taigetus is a mountain range in the Peloponnese peninsula in Southern Greece. The name is one of the oldest recorded in Europe, appearing in the Odyssey. In classical mythology, it was associated with the nymph Taygete...

 Massif on the west and the Parnon
Parnon
Parnon or Parnonas or Malevo is a mountain range, or massif, on the east of the Laconian plain and the Evrotas valley. It is visible from Athens above the top of the Argive mountains. The western part is in the Laconia prefecture and the northeastern part is in the Arcadia prefecture. The Parnon...

 Massif on the east, both limestone
Limestone
Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....

 ridges derived from the former sea bed. On the east side of Taygetus is the Sparta Fault, a normal fault, which strikes in a zig-zag path along the foot of the massif and dips toward the interior of the valley. The river is on the western side. From it the scarps of the footwall of the Sparta Fault are visible at the base of Tayegetus.

Taygetus is transected by deep ravines through which tributaries flow into the Eurotas. At the foot of the massif is a zone of scree
Scree
Scree, also called talus, is a term given to an accumulation of broken rock fragments at the base of crags, mountain cliffs, or valley shoulders. Landforms associated with these materials are sometimes called scree slopes or talus piles...

. To the east of that alluvial fan
Alluvial fan
An alluvial fan is a fan-shaped deposit formed where a fast flowing stream flattens, slows, and spreads typically at the exit of a canyon onto a flatter plain. A convergence of neighboring alluvial fans into a single apron of deposits against a slope is called a bajada, or compound alluvial...

s from Taygetus cover half the valley, making it asymmetrical. On that account it is often called the Evrotas Furrow. The Eurotas flows over a flood plain and also through a shallow aquifer
Aquifer
An aquifer is a wet underground layer of water-bearing permeable rock or unconsolidated materials from which groundwater can be usefully extracted using a water well. The study of water flow in aquifers and the characterization of aquifers is called hydrogeology...

 of sand and gravel 10-60 m deep, graded with the deep end downstream. The gradient of the aquifer is 1-3%, which is steep. The highest hydraulic conductivity
Hydraulic conductivity
Hydraulic conductivity, symbolically represented as K, is a property of vascular plants, soil or rock, that describes the ease with which water can move through pore spaces or fractures. It depends on the intrinsic permeability of the material and on the degree of saturation...

 and transmissivity are near the junction of the Xerias and the Eurotas south of Sparti. To the east are older and finer sediments of alternating clay
Clay
Clay is a general term including many combinations of one or more clay minerals with traces of metal oxides and organic matter. Geologic clay deposits are mostly composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure.- Formation :Clay minerals...

 and marl
Marl
Marl or marlstone is a calcium carbonate or lime-rich mud or mudstone which contains variable amounts of clays and aragonite. Marl was originally an old term loosely applied to a variety of materials, most of which occur as loose, earthy deposits consisting chiefly of an intimate mixture of clay...

 beds, some of which are impermeable. Under the entire valley is a deep aquifer in the limestone floor, containing water permeating downward through the horst
Horst
Horst is a Germanic word meaning "eagle's nest" and "man from the forest" . It may refer to:-Given name:* Horst * Horst Buchholz, a German actor* Horst Bulau, a Canadian ski jumper...

s. The Eurotas collects runoff and drains the deep aquifer on the east bank but loses water to the shallow aquifer on the west bank.

Recent geologic history

Analysis of bore holes in the valley indicate that in the Pliocene
Pliocene
The Pliocene Epoch is the period in the geologic timescale that extends from 5.332 million to 2.588 million years before present. It is the second and youngest epoch of the Neogene Period in the Cenozoic Era. The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch...

it was a lake. In classical times, according to the ancient authors, it was swampy, but the cultivatable land exposed was very fertile. Then, as now, it was used mainly for fruit trees, especially olive.

Geologic analysis done in the 20th century hypothesized that the Eurotas Valley in the Late Pliocene was an inland sea over the lower and middle valley several hundred m deep at the current mouth of the river. The fault-block geology had developed earlier. During the Pleistocene the sea level dropped 500 m (1,640.4 ft) exposing a flat floor. Continued slippage along the Sparta Fault dropped the middle Eurotas valley further forcing the river to cut its way through the 100-250 m hills dividing the lower from the middle valley, creating Eurotas Ravine.
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