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A late Holocene record of environmental changes from Kotihi lagoon, Elis, Northwest Peloponnesus, Greece
Quaternary International 225 (2010) 191–198
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A late Holocene record of environmental changes from Kotihi lagoon, Elis, Northwest Peloponnesus, Greece N. Kontopoulos*, A. Koutsios Department of Geology, University of Patras, 265 00 Patras, Greece
a r t i c l e i n f o
a b s t r a c t
Article history: Available online 18 October 2008
The late Holocene instability of the coastline of Elis was investigated using two boreholes. Three evolutionary stages are distinguished. (A) From earlier than 7000 to 3810 cal BP there was a static coastline and predominantly lagoon floor sediments accumulated. (B) From 3810 to 1400 cal BP, the rate of sedimentation was higher than the rate of relative sea level change, possibly because of the proximity of the mouth of the Peneus River, and predominantly fluvial sediments accumulated. (C) From 1400 cal BP to present time, landward migration of the coast and the re-establishment of lagoonal facies was probably the result of the avulsion of the Peneus River. From 150 cal BP until present, the rate of sedimentation in lagoon area was high about 5.2 mm/a. Ó 2008 Elsevier Ltd and INQUA. All rights reserved.
1. Introduction Coastal stratigraphic studies allow the recognition of coastline changes, which are controlled by rates of sediment supply, rates of eustatic sea level changes and rates and types of tectonic movement. The lagoonal area under study is located within the Elis region in the northwestern part of the Peloponnesus, Greece, on the ancient delta of the Peneus River. Here, tectonic movements and variations in water and sediment yield from streams are associated with coastal change (Bird, 1985). The main purpose of this study is to attempt a chronologic reconstruction of the late Holocene environmental evolution of Kotihi lagoon. Furthermore, this study tries to shed some light on the avulsion of the Peneus River, the relationships between the relative sea level changes and the rate of sedimentation, and the human impact on the late Holocene evolution of the lagoon. 2. Geological and tectonic setting The Kotihi lagoon is located along a wave dominated and microtidal coast in the northwestern Peloponnesus, about 40 km southwest of the city of Patras (38 010 N 21170 E) (Fig. 1). The lagoon is approximately orthogonal in shape and is situated on 6.32 ha of flat land at the northeastern tip of the Paleo-Peneus River. Westwards it is separated from the open sea by a low relief barrier island and has limited communication with the open sea, with a stable,
* Corresponding author. Tel.: þ30 2610 997591; fax: þ30 2610 996272. E-mail addresses: [email protected] (N. Kontopoulos), [email protected] (A. Koutsios). 1040-6182/$ – see front matter Ó 2008 Elsevier Ltd and INQUA. All rights reserved. doi:10.1016/j.quaint.2008.10.001
short and narrow inlet. Eastwards, on the landward lagoonal margins, small-scale deltas have prograded into the lagoon. Intertidal and supratidal mud flats are developed among the deltas, covered with plants, e.g. Salicornia. The lagoon is polysaline and exhibits a salinity ranging between 8& and 17&, during the winter rainy season, and from 20& to 37& during the summer (Bouzos and Kontopoulos, 2004). The average depth of the lagoon is only 0.5 m. The surface sediment is dominantly sandy mud (75%) and the remainder is clay and mud (Bouzos and Kontopoulos, 1998). The Corg content is 1.5–4% and CaCO3 content ranges from 6% to 42% (Bouzos and Kontopoulos, 1998). The sediment is very poorly to extremely poorly sorted, with generally coarse to very coarse skewness (Bouzos, unpublished data). The water surface of the lagoon was permanently lowered between 1945 and 2000. This event is a result of human activities including deforestation and agriculture, rapidly changing the ecological and environmental situation of the lagoon (Avramidis et al., 2008). The old Peneus river delta was located south of the Kotihi lagoon. The present Peneus River delta has been established since the 17th century AD (National Bank of Greece Cultural Foundation, 2006) probably by artificial diversion (Raphael 1973, 1978) (Fig. 1). The broad area of the Kotihi lagoon is located at the north part of the Ellis graben. This structure lies very close to the convergent boundary between the African and European plate and the diapirism area of the evaporites that belong to the Alpine basement. The neotectonic fault zones that occur in this part display a complex pattern, comprising NNW-SSE, NNE-SSW and WNW-ESE trending faults. Tectonic activity has occurred through the Holocene (Lekkas et al., 1992) and the most recent strong earthquake event (Mw 6.3) was June 8, 2008. During this event significant vertical displacements, up to 25 cm identified along a major high angle
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Fig. 2. Core KK profile showing location of samples, and corresponding units, texture, relative percentages of gravel, sand, silt and clay, organic carbon and calcium carbonate content (%). Fig. 1. Map showing the locality and the sub-environments of the Kotihi lagoon, positions of the cores and palaeogeography elements from Kraft et al. (2005). Boxes show (a) map of the geographic setting of the study area and (b) map of the geographic position of the modern Peneus river mouth.
NNW-striking, 6 km long co-seismic rupture segment (Kokkalas et al., 2008).
3.
3. Previous studies on the Kotihi lagoon coast Raphael (1973, 1978) examined the association between prehistoric and historic remains and the geomorphology of the Elis coastal plain. The main findings are the following: 1. Prehelladic and Helladic (Bronge Age) sites. These sites are located either on the Amalias surface or on pre-Quaternary surfaces, more than 2 km east of Kotihi lagoon. The Prehelladic and the Helladic cultures which were situated on the shore have been drowned since the shoreline prograded 3500 BP. 2. Natural levee systems. Two relict natural levee systems of the Peneus River. The first abandoned levee is directly south of Kotihi lagoon and eroded, and stands as a low sea cliff. If the levee scarp is projected seawards, it intersects the sea level
4.
5.
6.
approximately 1.2 Km offshore. The second ancestral levee, which is 5 Km to the southwest, stands well above the flood plain at the shoreline and also indicates coastal retreat. The age of the levee systems. Hellenistic artifacts are found on the levee systems. The second levee is characterized by an occupation site of Turkish age and the minimum age of this levee is about 200 years. During the Turkish period, the levee standing well above the flood plain of the shoreline indicates that the shore was farther seaward during the Middle Ages and has retreated since then. Beach ridge complex. North of Kotihi is a crescentic series of beach ridges. These are currently covered by eolian dunes. Roman sites were established on the beach ridges which suggest that the complex prograded continuously during the Roman time until about the end of the 5th century AD. The source area of the beach ridges. The presence of pottery of Roman age 40 cm bellow the crest of the first levee indicates that this channel was active during and after Roman time. Offshore foundations. Local inhabitants report the presence of foundations 100 m offshore at the south end of Kotihi lagoon. Roman potsherds have washed ashore and they tend to support the mentioned reports.
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underlain by a peat, which formed on the fringe of a lagoon. The peat yielded 14C dates of 991, 952, and 948 B.C. The dating depth is 2 m bellow the flood plain surface. The core study did not show any evidence that the Peneus River channel has shifted to the north and to the south of Chlemoutsi headland between the Neolithic period and 8th century A.D.
4. Methods Two sediment cores were obtained (Fig. 1) using an Eijkelkamp percussion corer. The sediment types, structure, colour, organic constituents, as well as contact depths and characteristics were recorded for each core in the field and each core was divided into a number of lithostratigraphic units. Laboratory studies included determination of grain-size distribution, total organic matter, total carbonate, micro and molluscan fossils for the selected samples (Figs. 2 and 3). Grain size was determined by classical sieve and pipette methods. Total and organic carbons were determined according to Gaudette et al. (1974). Percentages of sand and gravel components were estimated using a binocular microscope (c.f. Shepard and Moore, 1954). The microfossil assemblage present consists of two principal components: ostracodes, represented mostly by the genera Cyprideis (brackish) and Candona (fresh water), and foraminifera, including largely the genera Ammonia, Elphidium and Quinqueloculina (brackish to marine). This foraminifera assemblage is analogous with that found on the mud-flat coast of western Greece (Scott et al., 1979). The analysis of molluscan fauna reveals three gastropod genera (Cerithium/shallow marine, Hydrobia/brackish to fresh water and Planorbis/freshwater) and two pelecypod genera (Cardium and Chlamys/shallow marine to brackish). Lithofacies were interpreted based on these laboratory analyses, biogenic content, and relationship to other facies. Radiocarbon dating was carried out at Beta Analytic, Miami. Table 1 lists the dates obtained.
5. Core sedimentology and stratigraphy
Fig. 3. Core K profile showing units referred to in the text, sample locations, texture, relative percentages of gravel, sand, silt and clay, organic carbon and calcium carbonate content (%).
7. Kotihi barrier. The narrow barrier that separates Kotihi lagoon from the sea has migrated inland in recent years. Kraft et al. (2005) discussed the evolution of the coastal landforms along the coast of Elis over the past 7000 years. Their study for the coastal changes on the northwest coast of Elis was based on the archaeological evidence and two drill cores. Their first (P13) and second cores (P15) occur near cores K and KK of this study, respectively. Core 15 contained yellow oxidized clay and silt overlying a thin grey clay with marine micromolluscs. These molluscs are indicative of an earlier, highly saline coastal lagoon and are
Core KK is 9 m long. Eleven units (I–XI) have been identified throughout the core and these are summarized and interpreted in Table 2, in order of their occurrence from bottom to top. The lithostratigraphic sequence is characterized by three different lithofacies. The first lagoonal lithofacies occur in the lower and the middle part of the sequence, the second fluvial lithofacies in the upper part and the third marginal flood lithofacies in the upper most part. This vertical depositional succession indicates a regressive event in the middle of the stratigraphic sequence and a transgressive event in the upper part. Core K is 3 m long. Six units (I–VI) have been identified throughout the core and these are summarized and interpreted in Table 3 in order of their occurrence from bottom to top. The lithostratigraphic sequence is characterized by interbedded barrier sub-environments. This vertical depositional succession indicates a transgressive event.
Table 1 Radiocarbon dates of shell samples from the studied cores. No Kotihi Kotihi Kotihi Kotihi K7 K8
2 4 6 8
Cores
Units
Laboratory reference
KK
VII VII IV IV III II
Beta-194651 Beta-194652 Beta-194653 Beta-194654 Beta-242322 Beta-208983
K
(AMS) (AMS) (AMS) (AMS) (AMS) (AMS)
d (cm)
Material dated
355.50 397.80 604.80 737.00 78.00 104.00
Cardium Cardium Cardium Cardium Cardium Cardium
valve valve valve valve valve valve
Conventional age 14C years BP 40
Calibrated years BP 1s
Calibrated years BP 2s
2830 40 3860 40 5490 40 6410 40 520 40 770 40
2680–2510 3870–3800 5910–5860 6940–6840 240–90 460–390
2710–2460 3920–3700 5940–5760 6980–6780 260–40 480–310
Notes: No ¼ sample number, d (cm) ¼ depth in cm below surface, Beta ¼ beta analytic, and AMS ¼ accelerator mass spectrometer.
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Table 2 Description and interpretation of lithostratigraphic units of core KK. Units Lithological composition, colour (thickness and texture parameters in cm)
Sand fraction
Depositional environment
I (26)
Slightly gravelly mud/olive grey (5Y4/1) to olive black (5Y2/1)/extremely poorly sorting
Clastic grains (40%), Foraminifera [3% (Ammonia, Elphidium, Quinqueloculina & other miliolids)]/Ostracodes [2% (Candona, Cyprideis & other brackish species)], Malacofauna [30% (Cardium, whole & fragmentary shells)], Frora [Plant remains (5%)], Carbonate cemented grains (20%), (C)organic content (1.5%), Iron-oxide cemented grains (no present)
Lagoon bottom near river
II (39)
Silty sand, sand & slightly gravelly sand/greenish grey (5GY6/1)/moderately well sorting to moderately sorting/fine-skewness to very fine-skewness
Clastic grains (100%), Foraminifera [negligible (Ammonia, Elphidium)]/ Ostracodes (no present), Malacofauna [negligible (mollusc shell fragments)], Flora (no present), Carbonate cemented grains (no present), (C)organic content (0.00%–0.17%), Iron-oxide cemented grains (no present)
River channel
III (87)
Sandy silt, silt & clay/greenish grey (5GY6/1) to dark greenish grey (5GY4/1)/very poorly sorting
Clastic grains [upper part (0%) & lower part (80%–90%)], Bioclastic grains (1%–15%): Foraminifera (Ammonia, Quinqueloculina) & Ostracodes (Cyprideis), Malacofauna [mollusc shell fragments, gastropods (Planorbis)], Flora [rare charophytes, Plant remains (0%), except one sample (1%)], Carbonate cemented grains (no present, except one sample more than 80%), (C)organic content (0.07%–0.41%), Iron-oxide cemented grains [(0%–5%), except one sample (about 80%)]
Transitional zone between Lagoon bottom and river mouth
IV (255)
Slightly gravely mud, gravely mud, mud & clay/olive grey colour (5Y4/1)/very poorly sorting to extremely poorly sorting
Clastic grains (very rare to 70%), Foraminifera [very rare to 30% (Ammonia, Elphidium, Quinqueloculina)]/Ostracodes [very rare to 4% (Cyprideis)], Malacofauna [3%–87% (Cardium, Chlamys, Cerithium, Hydrobia, Planorbis, whole & fragmentary shells)], Flora [very rare charophytes, Plant remains (1%–11%)], Carbonate cemented grains (0%–32%), (C)organic content (1.14%–2.2%), Iron-oxide cemented grains (0%–1%)
Lagoon bottom
V (19)
Slightly gravelly muddy sand/greenish grey (5GY6/1)/very poorly sorting/very fine-skewness
Clastic grains (99%), Foraminifera (rare)/Ostracodes (rare), Malacofauna [mollusk shell fragments (1%)], Flora (no present), Carbonate cemented grains (no present), (C)organic content (0.15%–0.35%), Iron-oxide cemented grains (no present)
Floodplain
VI (66)
Slightly gravelly mud, gravelly mud & clay/olive grey (5Y4/1)/very poorly sorting to extremely poorly sorting
Clastic grains (no present), Bioclastic grains (83%–100%): Foraminifera (Ammonia, Quinqueloculina) & Ostracodes (Cyprideis), Malacofauna [Cardium, Chlamys, gastropods (whole & fragmentary shells)], Flora [Plant remains (0%), except one sample (17%)], Carbonate cemented grains (no present), (C)organic content (1.33%–2.52%), Iron-oxide cemented grains (no present)
Lagoon bottom
VII (47)
Slightly gravelly mud, gravelly mud & clay/olive grey (5Y4/1 to 5Y4/7)/Very poorly sorting to extremely poorly sorting
Clastic grains (no present), Foraminifera [(0%–1%), Ammonia]/Ostracodes [(0%–6.5%), Cyprideis & other brackish species], Malacofauna [mollusk shell fragments (5%–63%)], Flora [Plant remains (27%–100%)], Carbonate cemented grains (no present), (C)organic content (0%–6.58%), Iron-oxide cemented grains (no present)
Lagoon bottom close to marsh
VIII (60)
Clay/olive grey (5Y4/1)/very poorly sorting
Clastic grains [upper part (25%–40%) & lower part (0%)], Foraminifera Marginal terrestrial [very rare (Ammonia)]/Ostracodes [upper part (very rare) & lower part environment near brackish species (10%–30%)], Malacofauna [(5%–90%), Cardium, whole & river mouth fragmentary shells (lower part)], Flora [Plant remains upper part (very rare), except one sample (10%) & lower part (very rare to 65%), Carbonate cemented grains [no present, except one sample in the lower part (100%)], (C)organic content (0%–0.86%), Iron-oxide cemented grains [upper part (25%–45%)]
IX (95)
Clay, mud, silt, sandy silt, silty sand and gravelly sand/dark greenish grey (5G4/1), light olive grey, greenish grey (5Y7/2) and yellowish grey (5G7/2)/poorly sorting to very poorly sorting
Clastic grains (90%–100%), Foraminifera [0% to very rare), (Ammonia)]/ Ostracodes [0% to very rare (Cyprideis)], Malacofauna [mollusc shell fragments (rare to 1.5%)], Flora [very rare charophytes, Plant remains (0%), except one sample (98%)], Carbonate cemented grains (0%–10%), (C)organic content (0.04%–0.48%), Iron-oxide cemented grains (0%–10%)
Floodplain
X (92)
Slightly gravelly muddy sand/greenish grey (5G6/1), light olive grey (5Y5/2), dusky yellow green (5G5/2) to moderate yellowish brown (10YR5/6) and dark yellowish orange (10YR6/6)/moderately sorting to very poorly sorting/ near-symmetrical to very fine-skewness
Clastic grains (94%–100%), Foraminifera [negligible (Ammonia)]/Ostracodes [negligible (Cyprideis)], Malacofauna [(0%–0.5%), Hydrobia ventrosa, whole & fragmentary shells], Flora [negligible charophytes, Plant remains (0%)], Carbonate cemented grains (0%–4%), (C)organic content (0%), Iron-oxide cemented grains (0%–1.5%)
Marginal flood environment near river mouth
XI (104)
Slightly gravelly mud/dark, moderate, pale yellowish brown (10YR4/2, 5/6) to dark yellowish orange (10YR6/6)/very poorly sorting/fine-skewness to very fine-skewness
Clastic grains (80%–100%), Foraminifera [very rare (Ammonia)]/Ostracodes [very rare (Cyprideis)], Malacofauna (very rare mollusk shell fragments), Flora [no present], Carbonate cemented grains (0%–20%), (C)organic content (0%–0.51%), Iron-oxide cemented grains (0%–5%)
Marginal river flood environment
6. Radiocarbon dating Radiocarbon age determinations have been made on individual Cardium edulis shells from six horizons (Table 1). The shells were whole and very well preserved without erosional traces and there are no anomalous age-depth phenomena.
In such a marginal marine environment, the choice of a marine reservoir correction is difficult. Dominant fresh water supply was assumed for the samples Kotihi 2, Kotihi 4, K8 and marine water for the samples Kotihi 6 and Kotihi 8; if these assumptions are incorrect, the calibrated ages may change by as much as 500 a. The radiocarbon ages were converted to calendar ages (cal. BP) using
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Table 3 Description and interpretation of lithostratigraphic units of core K. Units (thickness in cm)
Lithological composition, colour and texture parameters
Sand fraction
Depositional environment
I (151)
Sand, slightly gravelly sand & clayey sand/dusky yellow (5Y7/6) to dark grey (No3) colour/moderately well sorting to very poorly sorting/very well roundness
Clastic grains (100%), Foraminifera [negligible (Ammonia, Elphidium & Quinqueloculina)]/ Ostracodes (negligible), Malacofauna (negligible mollusc shell fragments), Flora (negligible plant remains), Carbonate cemented grains (no present), (C)organic content (0.18%–0.26%), Iron-oxide cemented grains (no present)
Barrier sand dune/ washover fan
II (46)
Mud/dusky yellow (5Y6/4)/very poorly sorting
Clastic grains (80%–100%), Foraminifera [very rare (Ammonia)]/Ostracodes (very rare), Malacofauna (no present), Flora (very rare plant remains), Carbonate cemented grains [0%, except one sample (4%)], (C)organic content (0.19%–0.32%), Iron-oxide cemented grains (1%–20%)
Mud flat
III (36)
Slightly gravelly mud/dark greenish grey (5G4/1) to greenish black (5G2/1)/very poorly sorting to extremely poorly sorting
Clastic grains (30%–98%), Bioclastic grains (2%–40%, except plant remains): Foraminifera (Ammonia) & Ostracodes (brackish species), Malacofauna [whole & fragmentary shells (Cardium, Hydrobia, Cerithium)], Flora [Plant remains (0.5%–30%), Carbonate cemented grains (no present), (C)organic content (0.34%–1.71%), Iron-oxide cemented grains (no present)
Lagoon bottom near river mouth
IV (24)
Slightly gravelly sand/dark grey (No3)/moderately well sorting/near-symmetrical to coarse skewness
Clastic grains (100%), Foraminifera [negligible (Ammonia, Quinqueloculina)]/Ostracodes (negligible), Malacofauna (negligible mollusc shell fragments), Flora (negligible plant remains), Carbonate cemented grains (no present), (C)organic content (0%–0.18%), Iron-oxide cemented grains (no present)
Barrier beach
V (18)
Slightly gravelly muddy sand/black (No1)/very poorly sorting
Clastic grains (96%), Bioclastic grains (2%, except plant remains): Foraminifera (Ammonia, Elphidium, Quinqueloculina) & Ostracodes (no present), Malacofauna [whole & fragmentary shells (Cerithium, Cardium)], Flora [Plant remains (2%)], Carbonate cemented grains (no present), (C)organic content (0.78), Iron-oxide cemented grains (no present)
Washover fan
VI (25)
Slightly gravelly sand/dusky yellow (5Y7/6)/moderately sorting/fine-skewness
Clastic grains (97%), Bioclastic grains (3%): Foraminifera (Ammonia, Elphidium) & Ostracodes (present), Malacofauna (mollusc shell fragments), Flora (no present), Carbonate cemented grains (no present), (C)organic content (0.38%), Iron-oxide cemented grains (0%)
Barrier sand dune
the 1998 calibration data (Talma and Vogel, 1993; Stuiver et al., 1998). The base of Unit IV in core KK yielded an age of 6410 40 BP (cal. BP 6980–6780) (Kotihi 8) and the middle of Unit IV an age of 5490 40 BP (cal. BP 5940–5760) (Kotihi 6). The base of Unit VII gave an age of 3860 40 BP (cal. BP 3920–3700) (Kotihi 4) and the base of Unit VIII an age of 2830 40 BP (cal. BP 2710–2460) (Kotihi 2). In core K, the base of Unit III yielded an age of 770 40 BP (cal. BP 480–310) (K8) and 520 40 BP (cal. BP 260–40) for the middle of Unit III.
604.8 cm, 5850 cal BP; 397.5 cm, 3810 cal BP; 355.5 cm, 2585 cal BP) can be obtained, which are from bottom to top 1.28 mm/a (737–604.8 cm), 1.07 mm/a (604.5–397.5 cm), 0.34 mm/ a (397.5–355.5 cm) and 1.38 mm/a (355.5–0 cm). In core K, on the basis of two ages downcore (104 cm, 395 cal BP; 78 cm, 150 cal BP) two different rates of sedimentation can be obtained, which are from bottom to top 1.06 mm/a and 5.2 mm/a. This latter value of sedimentation agrees with the rate of sedimentation that was reported by Bouzos and Kontopoulos (1998) for Kotihi lagoon during the last 150 years.
7. Relative sea level changes and rate of sedimentation Vo¨tt (2007) illustrates the RSL curve for the Elis coastal plain, which is based on seven sedimentological sea level markers. According to this curve the RSL stood at 4.40 m b.s.l. on 5250 cal BC, at 3.70 m b.s.l. on 3900 cal BC and at 2.25 m b.s.l. on 1000 cal BC. This Elis sea level curve is quasilinear with a rate of 0.5 m/ka during 5250–1000 cal BC. Since that time, the value has slightly increased to 0.7 m/ka. The data of the present study show a rate of relative sea level rise about 0.95 m/ka during 4880–1810 cal BC, 1.2 m/ka during 1810–585 BC and 1.06 m/ka during 1555–1800 AD (the RSL stood at 6.9 m b.s.l. on 4880 cal BC, at 5.60 m b.s.l. on 3850 cal BC, at 3.53 m b.s.l. on 1810 cal BC, at 3.11 m b.s.l. on 585 cal BC, 0.64 m b.s.l. on 1555 cal AD and 0.38 m b.s.l. on 1800 AD) (Fig. 4). These results are not comparable with Vo¨tt’s (2007) results. The rate of sea level rise is double that of Vo¨tt (2007). However the rate of sea-level rise for the local Kotihi lagoon is the same as the mean sea level rise for northwestern Greece according to Vo¨tt (2007). The different values in Elis coast probably resulted because Vott’s samples were taken from the northern and from the southern part of Elis graben that had a different tectonic behavior, whereas samples for this study were taken only in the northern part. The lagoon area is characterized by four different rates of sedimentation on the basis of four ages downcore (737 cm, 6880 cal BP;
Fig. 4. Age-depth relation according to the date of borehole samples and the resulting local relative sea-level rise, Kotihi lagoon region. It is given the relative sea level rise according to Vo¨tt (2007) for reasons of comparison (see details in the text).
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Fig. 5. Stratigraphic correlations among the defined units of the cores.
8. Evolution of Kotihi lagoon The Holocene evolution of Kotihi lagoon can be divided into three stages, based on whether the area was under transgressive, regressive, or almost stationary relative sea level conditions (Fig. 5). Relative sea-level variations are a consequence of eustatic change in sea-level and the corresponding loading effects (Lambeck, 1995), tectonic deformation (e.g. Stamatopoulos and Kontopoulos, 1994), and sediment supply from the Peneus River, which has shifted its course over the Holocene (Raphael, 1978). 8.1. Stage A (6880–3810 cal BP) Kotihi lagoon was first established on the Paleo-Peneus delta plain earlier than 7000 BP. At this time, the rate of world sea level rise began to diminish (Lambeck, 1995). From this time to about 3810 cal BP (base of Unit VII) core KK penetrated relatively uniform
lagoonal bottom facies, with two minor episodes of greater stream influence. Thus, during this stage (from Neolithic to Early Bronze Age) lagoonal sedimentation appears to have approximately kept pace with rising sea level, so that the relative position of the lagoon remained stationary. 8.2. Stage B (3810–1400 BP) In units VII–IX in core KK, the facies change from lagoonal with plant material to marginal and then to full terrestrial. This facies sequence marks a regressive stage, probably as a result of deltaic progradation. This interval is dated from about 3810 to 1400 cal BP (?) on the basis of bounding radiocarbon and interpolated dates. There is a controversy about the reasons that caused the Mediterranean soil erosion during the Holocene. Some workers supported the idea of a dominant anthropogenic cause for this erosion (e.g., Pope and van Andel, 1984; Bru¨ckner, 1986, 1997, 1998; Cherry
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Fig. 6. Geographic maps of the 16th, 17th and 18th centuries indicate that the Peneus River mouth migrated between the two capes of Kyllini peninsula (National Bank of Greece Cultural Foundation, 2006).
et al., 1988; Van Andel et al., 1990; Fuchs, 2007). Others have attributed this erosion to climate factors (Vita-Vinzi 1969, 1976; Bintliff 1975, 1977, 1982). Bintliff (2002) and Pope et al. (2003) considered both the climatic and anthropogenic impact as causes of the Holocene erosion. Lespez (2003) and Fuchs (2007) suggest that only the human impact on the landscape results in accentuated soil erosion. Furthermore, Fuchs (2007) distinguishes four phases of strong erosion in southern Greece: a. Middle and Late Neolithic phase. b. Middle–Late Bronze phase. c. Classical/Roman phase and d. Ottoman phase. The stage B appears to belong to b and c phases. 8.3. Stage C (1400–present) In Unit X of core KK, the facies change from full terrestrial to marginal river flood deposits. This change is probably dated at 1400 BP and suggests the beginning of a transgressive period. In the same time interval in core K, sand dune subfacies of Unit I pass
upward into washover fan subfacies of Unit I and then into mud flat of Unit II (1150–395 cal BP). Thus in both cores, this stage is characterized by the effects of marine transgression. The landward migration of the coast probably is the result of the avulsion of the Peneus River to the south of the Kyllini peninsula (Fig. 1), cutting off sediment supply by a longshore drift. This shift in the Peneus River was probably the result of tectonic tilting marked by strong and destructive earthquakes during the 4th–6th century A.D. (Pirazzoli, 1986; Mouyaris, 1994; Stiros, 2001). In core K, from 395 cal BP to present, the facies change in succession from lagoonal (Unit III), beach (Unit IV), washover (Unit V) and sand dune (Unit VI). This sequence of facies corresponds to a retreat of the coastline. The rate of sedimentation was about 0.52 cm/a after 150 cal PB. This value is identical with that suggested by Bouzos and Kontopoulos (1998) due to the agriculture and the small streams that debouched into the lagoon. Fuchs (2007) refers a high rate of sedimentation from the middle Ottoman period until present times.
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9. Discussion The Kotihi lagoon existed in its present position at least from 7000 years ago. The Kraft’s borehole P15 has a core interval only 3 m below the surface and the base of this interval consists of a peat, corresponding to unit VII, and probably has formed on a sand or mud flat of the lagoonal margin. If borehole P15 was deeper then its core profile would be similar with the KK borehole profile. Kraft et al. (2005) suggested a Neolithic and Helladic coastline 2.7 km east of the present Kotihi lagoon. According to this suggestion, the Neolithic lobate Peneus River delta was established on this paleo-coast and the Kotihi barrier island developed by a longshore spit. Raphael (1978) concluded that this coastal area shows three events of coastal progradation during Hellenistic (4th–2nd cent. BC), Roman and early Medieval times (2nd cent. BC–6th cent. AD) and one event of coastal retreat during Turkish times (15th–18th cent. AD). This study not only suggests a coastal progradation during the Hellenistic, Roman and early Medieval times but also throughout the two last millennium BC. This progradation would have created the most seaward beach ridge approximately 1.2 km offshore (Raphael, 1978). Raphael (1973) reports a minimum age of the most landward beach ridge at 2300 BP. During the Dark Ages (600–900 AD), the Middle Byzantine Period (900–1261 AD) and the Frankish Period (1261–1453 AD), the coast retreated. Raphael (1978) reports that the second levee in the Turkish period, standing well above the flood plain at the shoreline, indicates that the shore has retreated from the Middle Ages. This probably suggests an avulsion of the Peneus River to south of the Kyllini peninsula (Fig. 1), thus cutting off sediment supply by a longshore drift. Geographic maps of the 16th, 17th and 18th centuries indicate that the Peneus River mouth migrated between the two capes of Kyllini peninsula (Fig. 6) (National Bank of Greece Cultural Foundation, 2006). During the Ottoman Period (1460–1827 AD) and Modern times (1827 AD– present) the coast retreated in its present position. 10. Conclusions Core stratigraphy and radiocarbon data define three stages in the evolution of Kotihi lagoon on the basis of the rate of relative sea level changes and the rate of sedimentation. During the first stage, from earlier than 7000 BP to 3810 cal BP, there was a balance between the rate of relative sea level change and the rate of sedimentation, as sea level continued to rise. In the second stage, from 3810 to 1400 cal BP (?), the rate of sedimentation was higher from the rate of relative sea level change, probably because of proximity of the mouth of the Peneus River and the high rates of sediment supply. In the third stage, from 1400 BP (?) to present, the landward migration of the coast was probably the result of the avulsion of the Peneus River. Acknowledgements We wish to thank Dr. D.J.W. Piper (Bedford Institute of Oceanography, Canada) for his useful suggestions and comments on the manuscript. We wish to acknowledge Dr. D.B. Scott (University of Dalhousie) who examined some samples for ostracodes and foraminifera. The research was funded by research committee of University of Patras, Grant FK2441. References Avramidis, P., Bouzos, D., Antoniou, V., Kontopoulos, N., 2008. Application of grain size trend analysis and spatio-temporal changes of sedimentation, a tool for lagoon management. Case study: the Kotychi lagoon (western Greece). Geologica Carpathica 59 (3), 261–268. Bintliff, J.L., 1975. Mediterranean alluviation: new evidence from archaeology. Proceedings of the Prehistoric Society 41, 78–84. Bintliff, J., 1977. Natural environment and human settlement in Greece. In: British Archaeological Reports, vol. 28. British Archaeological Museum, Oxford.
Bintliff, J., 1982. Paleoclimatic modelling of environmental changes in the East Mediterranean region since the last glaciation. In: Bintliff, J.L., van Zeist, W. (Eds.), Paleoclimates, Paleoenvironments and Human Communities in the Eastern Mediterranean Region in Later Prehistory. British Archaeological Reports, International Series, Oxford, 133 pp. Bintliff, J., 2002. Time, process and catastrophism in the study of Mediterranean alluvial history: a review. World Archaeology 33, 417–435. Bird, E., 1985. Coastline Changes. A Global Review. J.Wiley and Sons, Chichester, 219 pp. Bouzos, D., Kontopoulos, N., 1998. Recent sedimentation in the lagoons of the western Greece. Example the Kotihi lagoon. Bulletin of the Geological Society of Greece XXXII (2), 237–245. Bouzos, D., Kontopoulos, N., 2004. Oceanographic observations in the lagoon of Kotihi (W Peloponnesus). In: Seventh Panhellinic Geographical Conference of the Hellenic Geographical Society. Proceedings, vol. 1, pp. 340–347. Bru¨ckner, H., 1986. Man’s impact on the evolution of the physical environment in the Mediterranean region in historical times. GeoJournal 13, 7–17. Bru¨ckner, H., 1997. Coastal changes in western Turkey: rapid delta progradation in historical times. In: Briand, F., Maldonado, A. (Eds.), Transformations and Evolution of the Mediterranean Coastline. CIESM Science Series, vol. 3, pp. 63–74. Bru¨ckner, H., 1998. Coastal research and geoarchaeology in the Mediterranean region. In: Kelletat, D. (Ed.), German Geographical Coastal Research: the Last Decade. Institute for Scientific Cooperation, Tu¨bingen, pp. 235–257. Cherry, J.F., Davis, J.L., Demitrack, A., Mantzourani, E., Strasser, T.F., Talalay, L.E., 1988. Archaeological survey in an artifact-rich landscape: a middle Neolithic example from Nemea, Greece. American Journal of Archaeology 92, 159–176. Fuchs, M., 2007. An assessment of human versus climatic impacts on Holocene soil erosion in NE Peloponnesus, Greece. Quaternary Research 67, 349–356. Gaudette, H., Flight, W., Toner, L., Folger, D., 1974. An inexpensive titration method for the determination of organic carbon in recent sediments. Journal of Sedimentary Petrology 44, 249–253. Kokkalas, S., Xypolias, P., Koukouvelas, I., 2008. Surface ruptures of the recent Mw 6.3 (June 08, 2008) earthquake event in the northwestern Peloponnese: preliminaryfieldreport. http://www.emsc-csem.org/Doc/20080608_GREECE/Surface_ ruptures.pdf. Kraft, J.C., RappRip, G., Gifford, J.A., Aschenbrenner, S.E., 2005. Coastal change and Archaeological setting in Elis. Hesperia 74, 1–39. Lambeck, K., 1995. Late Pleistocene and Holocene sea-level change in Greece and south-western Turkey: a separation of eustatic, isostatic and tectonic contributions. Geophysical Journal International 122, 1022–1044. Lekkas, E., Papanikolaou, D., Fountoulis, I., 1992. Pyrgos and Tropaea. Neotectonic map of Greece, at scale 1/100,000. Earthquake Planning and Protection Organization, unpublished. Lespez, L., 2003. Geomorphic responses to long-term land use changes in Eastern Macedonia (Greece). Catena 51, 181–208. Mouyaris, N., 1994. Seismic history of the Aegean area. Unpublished PhD thesis, University of Patras, Patras, Greece (in Greek language with English abstract). National Bank of Greece Cultural Foundation, 2006. The Peloponnesus Cartography and History. 16th–18th century. NBGCF, Athens, 197 pp. Pirazzoli, P.A., 1986. The early Byzantine tectonic paroxysm. Zeitschrift fu¨r Geomorphologie 62 (Suppl.), 31–49. Pope, K.O., van Andel, T.H., 1984. Late Quaternary alluviation and soil formation in the Southern Argolid: its history, causes and archaeological implications. Journal of Archaeological Science 11, 281–306. Pope, R.J.J., Wilkinson, K.N., Millington, A.C., 2003. Human and climatic impact on Late Quaternary deposition in the Sparta Basin Piedmont: evidence from alluvial fan systems. Geoarchaeology 18, 685–724. Raphael, C.N., 1973. Late Quaternary changes in coastal Elis, Greece. Geographical Review 63, 73–89. Raphael, C.N., 1978. The erosional history of the plain of Elis in the Peloponnesus. In: Brice, W.C. (Ed.), The Environmental History of the Near and Middle East Since the Last Ice Age. Academic Press, London, pp. 51–66. Scott, D.B., Piper, D.J.W., Panagos, A.G., 1979. Recent salt marsh and intertidal mudflat foraminifera from the western coast of Greece. Rivista Italiana di Paleontologia 85, 243–266. Shepard, F.P., Moore, D.G., 1954. Sedimentary environments differentiated by coarse-fraction studies. AAPG Bulletin 38 (8), 1792–1802. Stamatopoulos, L., Kontopoulos, N., 1994. Geomorphology and evolution of the region between Lapa and Eleotopos, NW Peloponnesus, Greece. Il Quaternario 7 (2b), 537–544. Stiros, S.C., 2001. The AD 365 Crete earthquake and possible seismic clustering during the fourth to sixth centuries AD in the Eastern Mediterranean: a review of historical and archaeological data. Journal of Structural Geology 23, 545–562. Stuiver, M., Reiner, P.J., Bard, E., Beck, J.W., Burr, G.S., Hughen, K.A., Kromer, B., Mc Cormac, G., Van der Plicht, J., Spurk, M., 1998. INTCAL 98 radiocarbon age calibration. Radiocarbon 40 (3), 1041–1083. Talma, A.S., Vogel, J.C., 1993. A simplified approach to calibrating C14 dates. Radiocarbon 65 (2), 317–322. Van Andel, T.H., Zangger, E., Demitrack, A., 1990. Land use and soil erosion in prehistoric and historical Greece. Journal of Field Archaeology 17, 379–396. Vo¨tt, A., 2007. Relative sea level changes and regional tectonic evolution of seven coastal areas in NW Greece since the mid-Holocene. Quaternary Science Reviews 26 (7–8), 894–919. Vita-Vinzi, C., 1969. The Mediterranean Valleys. University Press, New York. Vita-Vinzi, C., 1976. Diachronism in old World alluvial sequences. Nature, 263 pp.
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A late Holocene record of environmental changes from Kotihi lagoon, Elis, Northwest Peloponnesus, Greece N. Kontopoulos*, A. Koutsios Department of Geology, University of Patras, 265 00 Patras, Greece
a r t i c l e i n f o
a b s t r a c t
Article history: Available online 18 October 2008
The late Holocene instability of the coastline of Elis was investigated using two boreholes. Three evolutionary stages are distinguished. (A) From earlier than 7000 to 3810 cal BP there was a static coastline and predominantly lagoon floor sediments accumulated. (B) From 3810 to 1400 cal BP, the rate of sedimentation was higher than the rate of relative sea level change, possibly because of the proximity of the mouth of the Peneus River, and predominantly fluvial sediments accumulated. (C) From 1400 cal BP to present time, landward migration of the coast and the re-establishment of lagoonal facies was probably the result of the avulsion of the Peneus River. From 150 cal BP until present, the rate of sedimentation in lagoon area was high about 5.2 mm/a. Ó 2008 Elsevier Ltd and INQUA. All rights reserved.
1. Introduction Coastal stratigraphic studies allow the recognition of coastline changes, which are controlled by rates of sediment supply, rates of eustatic sea level changes and rates and types of tectonic movement. The lagoonal area under study is located within the Elis region in the northwestern part of the Peloponnesus, Greece, on the ancient delta of the Peneus River. Here, tectonic movements and variations in water and sediment yield from streams are associated with coastal change (Bird, 1985). The main purpose of this study is to attempt a chronologic reconstruction of the late Holocene environmental evolution of Kotihi lagoon. Furthermore, this study tries to shed some light on the avulsion of the Peneus River, the relationships between the relative sea level changes and the rate of sedimentation, and the human impact on the late Holocene evolution of the lagoon. 2. Geological and tectonic setting The Kotihi lagoon is located along a wave dominated and microtidal coast in the northwestern Peloponnesus, about 40 km southwest of the city of Patras (38 010 N 21170 E) (Fig. 1). The lagoon is approximately orthogonal in shape and is situated on 6.32 ha of flat land at the northeastern tip of the Paleo-Peneus River. Westwards it is separated from the open sea by a low relief barrier island and has limited communication with the open sea, with a stable,
* Corresponding author. Tel.: þ30 2610 997591; fax: þ30 2610 996272. E-mail addresses: [email protected] (N. Kontopoulos), [email protected] (A. Koutsios). 1040-6182/$ – see front matter Ó 2008 Elsevier Ltd and INQUA. All rights reserved. doi:10.1016/j.quaint.2008.10.001
short and narrow inlet. Eastwards, on the landward lagoonal margins, small-scale deltas have prograded into the lagoon. Intertidal and supratidal mud flats are developed among the deltas, covered with plants, e.g. Salicornia. The lagoon is polysaline and exhibits a salinity ranging between 8& and 17&, during the winter rainy season, and from 20& to 37& during the summer (Bouzos and Kontopoulos, 2004). The average depth of the lagoon is only 0.5 m. The surface sediment is dominantly sandy mud (75%) and the remainder is clay and mud (Bouzos and Kontopoulos, 1998). The Corg content is 1.5–4% and CaCO3 content ranges from 6% to 42% (Bouzos and Kontopoulos, 1998). The sediment is very poorly to extremely poorly sorted, with generally coarse to very coarse skewness (Bouzos, unpublished data). The water surface of the lagoon was permanently lowered between 1945 and 2000. This event is a result of human activities including deforestation and agriculture, rapidly changing the ecological and environmental situation of the lagoon (Avramidis et al., 2008). The old Peneus river delta was located south of the Kotihi lagoon. The present Peneus River delta has been established since the 17th century AD (National Bank of Greece Cultural Foundation, 2006) probably by artificial diversion (Raphael 1973, 1978) (Fig. 1). The broad area of the Kotihi lagoon is located at the north part of the Ellis graben. This structure lies very close to the convergent boundary between the African and European plate and the diapirism area of the evaporites that belong to the Alpine basement. The neotectonic fault zones that occur in this part display a complex pattern, comprising NNW-SSE, NNE-SSW and WNW-ESE trending faults. Tectonic activity has occurred through the Holocene (Lekkas et al., 1992) and the most recent strong earthquake event (Mw 6.3) was June 8, 2008. During this event significant vertical displacements, up to 25 cm identified along a major high angle
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Fig. 2. Core KK profile showing location of samples, and corresponding units, texture, relative percentages of gravel, sand, silt and clay, organic carbon and calcium carbonate content (%). Fig. 1. Map showing the locality and the sub-environments of the Kotihi lagoon, positions of the cores and palaeogeography elements from Kraft et al. (2005). Boxes show (a) map of the geographic setting of the study area and (b) map of the geographic position of the modern Peneus river mouth.
NNW-striking, 6 km long co-seismic rupture segment (Kokkalas et al., 2008).
3.
3. Previous studies on the Kotihi lagoon coast Raphael (1973, 1978) examined the association between prehistoric and historic remains and the geomorphology of the Elis coastal plain. The main findings are the following: 1. Prehelladic and Helladic (Bronge Age) sites. These sites are located either on the Amalias surface or on pre-Quaternary surfaces, more than 2 km east of Kotihi lagoon. The Prehelladic and the Helladic cultures which were situated on the shore have been drowned since the shoreline prograded 3500 BP. 2. Natural levee systems. Two relict natural levee systems of the Peneus River. The first abandoned levee is directly south of Kotihi lagoon and eroded, and stands as a low sea cliff. If the levee scarp is projected seawards, it intersects the sea level
4.
5.
6.
approximately 1.2 Km offshore. The second ancestral levee, which is 5 Km to the southwest, stands well above the flood plain at the shoreline and also indicates coastal retreat. The age of the levee systems. Hellenistic artifacts are found on the levee systems. The second levee is characterized by an occupation site of Turkish age and the minimum age of this levee is about 200 years. During the Turkish period, the levee standing well above the flood plain of the shoreline indicates that the shore was farther seaward during the Middle Ages and has retreated since then. Beach ridge complex. North of Kotihi is a crescentic series of beach ridges. These are currently covered by eolian dunes. Roman sites were established on the beach ridges which suggest that the complex prograded continuously during the Roman time until about the end of the 5th century AD. The source area of the beach ridges. The presence of pottery of Roman age 40 cm bellow the crest of the first levee indicates that this channel was active during and after Roman time. Offshore foundations. Local inhabitants report the presence of foundations 100 m offshore at the south end of Kotihi lagoon. Roman potsherds have washed ashore and they tend to support the mentioned reports.
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underlain by a peat, which formed on the fringe of a lagoon. The peat yielded 14C dates of 991, 952, and 948 B.C. The dating depth is 2 m bellow the flood plain surface. The core study did not show any evidence that the Peneus River channel has shifted to the north and to the south of Chlemoutsi headland between the Neolithic period and 8th century A.D.
4. Methods Two sediment cores were obtained (Fig. 1) using an Eijkelkamp percussion corer. The sediment types, structure, colour, organic constituents, as well as contact depths and characteristics were recorded for each core in the field and each core was divided into a number of lithostratigraphic units. Laboratory studies included determination of grain-size distribution, total organic matter, total carbonate, micro and molluscan fossils for the selected samples (Figs. 2 and 3). Grain size was determined by classical sieve and pipette methods. Total and organic carbons were determined according to Gaudette et al. (1974). Percentages of sand and gravel components were estimated using a binocular microscope (c.f. Shepard and Moore, 1954). The microfossil assemblage present consists of two principal components: ostracodes, represented mostly by the genera Cyprideis (brackish) and Candona (fresh water), and foraminifera, including largely the genera Ammonia, Elphidium and Quinqueloculina (brackish to marine). This foraminifera assemblage is analogous with that found on the mud-flat coast of western Greece (Scott et al., 1979). The analysis of molluscan fauna reveals three gastropod genera (Cerithium/shallow marine, Hydrobia/brackish to fresh water and Planorbis/freshwater) and two pelecypod genera (Cardium and Chlamys/shallow marine to brackish). Lithofacies were interpreted based on these laboratory analyses, biogenic content, and relationship to other facies. Radiocarbon dating was carried out at Beta Analytic, Miami. Table 1 lists the dates obtained.
5. Core sedimentology and stratigraphy
Fig. 3. Core K profile showing units referred to in the text, sample locations, texture, relative percentages of gravel, sand, silt and clay, organic carbon and calcium carbonate content (%).
7. Kotihi barrier. The narrow barrier that separates Kotihi lagoon from the sea has migrated inland in recent years. Kraft et al. (2005) discussed the evolution of the coastal landforms along the coast of Elis over the past 7000 years. Their study for the coastal changes on the northwest coast of Elis was based on the archaeological evidence and two drill cores. Their first (P13) and second cores (P15) occur near cores K and KK of this study, respectively. Core 15 contained yellow oxidized clay and silt overlying a thin grey clay with marine micromolluscs. These molluscs are indicative of an earlier, highly saline coastal lagoon and are
Core KK is 9 m long. Eleven units (I–XI) have been identified throughout the core and these are summarized and interpreted in Table 2, in order of their occurrence from bottom to top. The lithostratigraphic sequence is characterized by three different lithofacies. The first lagoonal lithofacies occur in the lower and the middle part of the sequence, the second fluvial lithofacies in the upper part and the third marginal flood lithofacies in the upper most part. This vertical depositional succession indicates a regressive event in the middle of the stratigraphic sequence and a transgressive event in the upper part. Core K is 3 m long. Six units (I–VI) have been identified throughout the core and these are summarized and interpreted in Table 3 in order of their occurrence from bottom to top. The lithostratigraphic sequence is characterized by interbedded barrier sub-environments. This vertical depositional succession indicates a transgressive event.
Table 1 Radiocarbon dates of shell samples from the studied cores. No Kotihi Kotihi Kotihi Kotihi K7 K8
2 4 6 8
Cores
Units
Laboratory reference
KK
VII VII IV IV III II
Beta-194651 Beta-194652 Beta-194653 Beta-194654 Beta-242322 Beta-208983
K
(AMS) (AMS) (AMS) (AMS) (AMS) (AMS)
d (cm)
Material dated
355.50 397.80 604.80 737.00 78.00 104.00
Cardium Cardium Cardium Cardium Cardium Cardium
valve valve valve valve valve valve
Conventional age 14C years BP 40
Calibrated years BP 1s
Calibrated years BP 2s
2830 40 3860 40 5490 40 6410 40 520 40 770 40
2680–2510 3870–3800 5910–5860 6940–6840 240–90 460–390
2710–2460 3920–3700 5940–5760 6980–6780 260–40 480–310
Notes: No ¼ sample number, d (cm) ¼ depth in cm below surface, Beta ¼ beta analytic, and AMS ¼ accelerator mass spectrometer.
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Table 2 Description and interpretation of lithostratigraphic units of core KK. Units Lithological composition, colour (thickness and texture parameters in cm)
Sand fraction
Depositional environment
I (26)
Slightly gravelly mud/olive grey (5Y4/1) to olive black (5Y2/1)/extremely poorly sorting
Clastic grains (40%), Foraminifera [3% (Ammonia, Elphidium, Quinqueloculina & other miliolids)]/Ostracodes [2% (Candona, Cyprideis & other brackish species)], Malacofauna [30% (Cardium, whole & fragmentary shells)], Frora [Plant remains (5%)], Carbonate cemented grains (20%), (C)organic content (1.5%), Iron-oxide cemented grains (no present)
Lagoon bottom near river
II (39)
Silty sand, sand & slightly gravelly sand/greenish grey (5GY6/1)/moderately well sorting to moderately sorting/fine-skewness to very fine-skewness
Clastic grains (100%), Foraminifera [negligible (Ammonia, Elphidium)]/ Ostracodes (no present), Malacofauna [negligible (mollusc shell fragments)], Flora (no present), Carbonate cemented grains (no present), (C)organic content (0.00%–0.17%), Iron-oxide cemented grains (no present)
River channel
III (87)
Sandy silt, silt & clay/greenish grey (5GY6/1) to dark greenish grey (5GY4/1)/very poorly sorting
Clastic grains [upper part (0%) & lower part (80%–90%)], Bioclastic grains (1%–15%): Foraminifera (Ammonia, Quinqueloculina) & Ostracodes (Cyprideis), Malacofauna [mollusc shell fragments, gastropods (Planorbis)], Flora [rare charophytes, Plant remains (0%), except one sample (1%)], Carbonate cemented grains (no present, except one sample more than 80%), (C)organic content (0.07%–0.41%), Iron-oxide cemented grains [(0%–5%), except one sample (about 80%)]
Transitional zone between Lagoon bottom and river mouth
IV (255)
Slightly gravely mud, gravely mud, mud & clay/olive grey colour (5Y4/1)/very poorly sorting to extremely poorly sorting
Clastic grains (very rare to 70%), Foraminifera [very rare to 30% (Ammonia, Elphidium, Quinqueloculina)]/Ostracodes [very rare to 4% (Cyprideis)], Malacofauna [3%–87% (Cardium, Chlamys, Cerithium, Hydrobia, Planorbis, whole & fragmentary shells)], Flora [very rare charophytes, Plant remains (1%–11%)], Carbonate cemented grains (0%–32%), (C)organic content (1.14%–2.2%), Iron-oxide cemented grains (0%–1%)
Lagoon bottom
V (19)
Slightly gravelly muddy sand/greenish grey (5GY6/1)/very poorly sorting/very fine-skewness
Clastic grains (99%), Foraminifera (rare)/Ostracodes (rare), Malacofauna [mollusk shell fragments (1%)], Flora (no present), Carbonate cemented grains (no present), (C)organic content (0.15%–0.35%), Iron-oxide cemented grains (no present)
Floodplain
VI (66)
Slightly gravelly mud, gravelly mud & clay/olive grey (5Y4/1)/very poorly sorting to extremely poorly sorting
Clastic grains (no present), Bioclastic grains (83%–100%): Foraminifera (Ammonia, Quinqueloculina) & Ostracodes (Cyprideis), Malacofauna [Cardium, Chlamys, gastropods (whole & fragmentary shells)], Flora [Plant remains (0%), except one sample (17%)], Carbonate cemented grains (no present), (C)organic content (1.33%–2.52%), Iron-oxide cemented grains (no present)
Lagoon bottom
VII (47)
Slightly gravelly mud, gravelly mud & clay/olive grey (5Y4/1 to 5Y4/7)/Very poorly sorting to extremely poorly sorting
Clastic grains (no present), Foraminifera [(0%–1%), Ammonia]/Ostracodes [(0%–6.5%), Cyprideis & other brackish species], Malacofauna [mollusk shell fragments (5%–63%)], Flora [Plant remains (27%–100%)], Carbonate cemented grains (no present), (C)organic content (0%–6.58%), Iron-oxide cemented grains (no present)
Lagoon bottom close to marsh
VIII (60)
Clay/olive grey (5Y4/1)/very poorly sorting
Clastic grains [upper part (25%–40%) & lower part (0%)], Foraminifera Marginal terrestrial [very rare (Ammonia)]/Ostracodes [upper part (very rare) & lower part environment near brackish species (10%–30%)], Malacofauna [(5%–90%), Cardium, whole & river mouth fragmentary shells (lower part)], Flora [Plant remains upper part (very rare), except one sample (10%) & lower part (very rare to 65%), Carbonate cemented grains [no present, except one sample in the lower part (100%)], (C)organic content (0%–0.86%), Iron-oxide cemented grains [upper part (25%–45%)]
IX (95)
Clay, mud, silt, sandy silt, silty sand and gravelly sand/dark greenish grey (5G4/1), light olive grey, greenish grey (5Y7/2) and yellowish grey (5G7/2)/poorly sorting to very poorly sorting
Clastic grains (90%–100%), Foraminifera [0% to very rare), (Ammonia)]/ Ostracodes [0% to very rare (Cyprideis)], Malacofauna [mollusc shell fragments (rare to 1.5%)], Flora [very rare charophytes, Plant remains (0%), except one sample (98%)], Carbonate cemented grains (0%–10%), (C)organic content (0.04%–0.48%), Iron-oxide cemented grains (0%–10%)
Floodplain
X (92)
Slightly gravelly muddy sand/greenish grey (5G6/1), light olive grey (5Y5/2), dusky yellow green (5G5/2) to moderate yellowish brown (10YR5/6) and dark yellowish orange (10YR6/6)/moderately sorting to very poorly sorting/ near-symmetrical to very fine-skewness
Clastic grains (94%–100%), Foraminifera [negligible (Ammonia)]/Ostracodes [negligible (Cyprideis)], Malacofauna [(0%–0.5%), Hydrobia ventrosa, whole & fragmentary shells], Flora [negligible charophytes, Plant remains (0%)], Carbonate cemented grains (0%–4%), (C)organic content (0%), Iron-oxide cemented grains (0%–1.5%)
Marginal flood environment near river mouth
XI (104)
Slightly gravelly mud/dark, moderate, pale yellowish brown (10YR4/2, 5/6) to dark yellowish orange (10YR6/6)/very poorly sorting/fine-skewness to very fine-skewness
Clastic grains (80%–100%), Foraminifera [very rare (Ammonia)]/Ostracodes [very rare (Cyprideis)], Malacofauna (very rare mollusk shell fragments), Flora [no present], Carbonate cemented grains (0%–20%), (C)organic content (0%–0.51%), Iron-oxide cemented grains (0%–5%)
Marginal river flood environment
6. Radiocarbon dating Radiocarbon age determinations have been made on individual Cardium edulis shells from six horizons (Table 1). The shells were whole and very well preserved without erosional traces and there are no anomalous age-depth phenomena.
In such a marginal marine environment, the choice of a marine reservoir correction is difficult. Dominant fresh water supply was assumed for the samples Kotihi 2, Kotihi 4, K8 and marine water for the samples Kotihi 6 and Kotihi 8; if these assumptions are incorrect, the calibrated ages may change by as much as 500 a. The radiocarbon ages were converted to calendar ages (cal. BP) using
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Table 3 Description and interpretation of lithostratigraphic units of core K. Units (thickness in cm)
Lithological composition, colour and texture parameters
Sand fraction
Depositional environment
I (151)
Sand, slightly gravelly sand & clayey sand/dusky yellow (5Y7/6) to dark grey (No3) colour/moderately well sorting to very poorly sorting/very well roundness
Clastic grains (100%), Foraminifera [negligible (Ammonia, Elphidium & Quinqueloculina)]/ Ostracodes (negligible), Malacofauna (negligible mollusc shell fragments), Flora (negligible plant remains), Carbonate cemented grains (no present), (C)organic content (0.18%–0.26%), Iron-oxide cemented grains (no present)
Barrier sand dune/ washover fan
II (46)
Mud/dusky yellow (5Y6/4)/very poorly sorting
Clastic grains (80%–100%), Foraminifera [very rare (Ammonia)]/Ostracodes (very rare), Malacofauna (no present), Flora (very rare plant remains), Carbonate cemented grains [0%, except one sample (4%)], (C)organic content (0.19%–0.32%), Iron-oxide cemented grains (1%–20%)
Mud flat
III (36)
Slightly gravelly mud/dark greenish grey (5G4/1) to greenish black (5G2/1)/very poorly sorting to extremely poorly sorting
Clastic grains (30%–98%), Bioclastic grains (2%–40%, except plant remains): Foraminifera (Ammonia) & Ostracodes (brackish species), Malacofauna [whole & fragmentary shells (Cardium, Hydrobia, Cerithium)], Flora [Plant remains (0.5%–30%), Carbonate cemented grains (no present), (C)organic content (0.34%–1.71%), Iron-oxide cemented grains (no present)
Lagoon bottom near river mouth
IV (24)
Slightly gravelly sand/dark grey (No3)/moderately well sorting/near-symmetrical to coarse skewness
Clastic grains (100%), Foraminifera [negligible (Ammonia, Quinqueloculina)]/Ostracodes (negligible), Malacofauna (negligible mollusc shell fragments), Flora (negligible plant remains), Carbonate cemented grains (no present), (C)organic content (0%–0.18%), Iron-oxide cemented grains (no present)
Barrier beach
V (18)
Slightly gravelly muddy sand/black (No1)/very poorly sorting
Clastic grains (96%), Bioclastic grains (2%, except plant remains): Foraminifera (Ammonia, Elphidium, Quinqueloculina) & Ostracodes (no present), Malacofauna [whole & fragmentary shells (Cerithium, Cardium)], Flora [Plant remains (2%)], Carbonate cemented grains (no present), (C)organic content (0.78), Iron-oxide cemented grains (no present)
Washover fan
VI (25)
Slightly gravelly sand/dusky yellow (5Y7/6)/moderately sorting/fine-skewness
Clastic grains (97%), Bioclastic grains (3%): Foraminifera (Ammonia, Elphidium) & Ostracodes (present), Malacofauna (mollusc shell fragments), Flora (no present), Carbonate cemented grains (no present), (C)organic content (0.38%), Iron-oxide cemented grains (0%)
Barrier sand dune
the 1998 calibration data (Talma and Vogel, 1993; Stuiver et al., 1998). The base of Unit IV in core KK yielded an age of 6410 40 BP (cal. BP 6980–6780) (Kotihi 8) and the middle of Unit IV an age of 5490 40 BP (cal. BP 5940–5760) (Kotihi 6). The base of Unit VII gave an age of 3860 40 BP (cal. BP 3920–3700) (Kotihi 4) and the base of Unit VIII an age of 2830 40 BP (cal. BP 2710–2460) (Kotihi 2). In core K, the base of Unit III yielded an age of 770 40 BP (cal. BP 480–310) (K8) and 520 40 BP (cal. BP 260–40) for the middle of Unit III.
604.8 cm, 5850 cal BP; 397.5 cm, 3810 cal BP; 355.5 cm, 2585 cal BP) can be obtained, which are from bottom to top 1.28 mm/a (737–604.8 cm), 1.07 mm/a (604.5–397.5 cm), 0.34 mm/ a (397.5–355.5 cm) and 1.38 mm/a (355.5–0 cm). In core K, on the basis of two ages downcore (104 cm, 395 cal BP; 78 cm, 150 cal BP) two different rates of sedimentation can be obtained, which are from bottom to top 1.06 mm/a and 5.2 mm/a. This latter value of sedimentation agrees with the rate of sedimentation that was reported by Bouzos and Kontopoulos (1998) for Kotihi lagoon during the last 150 years.
7. Relative sea level changes and rate of sedimentation Vo¨tt (2007) illustrates the RSL curve for the Elis coastal plain, which is based on seven sedimentological sea level markers. According to this curve the RSL stood at 4.40 m b.s.l. on 5250 cal BC, at 3.70 m b.s.l. on 3900 cal BC and at 2.25 m b.s.l. on 1000 cal BC. This Elis sea level curve is quasilinear with a rate of 0.5 m/ka during 5250–1000 cal BC. Since that time, the value has slightly increased to 0.7 m/ka. The data of the present study show a rate of relative sea level rise about 0.95 m/ka during 4880–1810 cal BC, 1.2 m/ka during 1810–585 BC and 1.06 m/ka during 1555–1800 AD (the RSL stood at 6.9 m b.s.l. on 4880 cal BC, at 5.60 m b.s.l. on 3850 cal BC, at 3.53 m b.s.l. on 1810 cal BC, at 3.11 m b.s.l. on 585 cal BC, 0.64 m b.s.l. on 1555 cal AD and 0.38 m b.s.l. on 1800 AD) (Fig. 4). These results are not comparable with Vo¨tt’s (2007) results. The rate of sea level rise is double that of Vo¨tt (2007). However the rate of sea-level rise for the local Kotihi lagoon is the same as the mean sea level rise for northwestern Greece according to Vo¨tt (2007). The different values in Elis coast probably resulted because Vott’s samples were taken from the northern and from the southern part of Elis graben that had a different tectonic behavior, whereas samples for this study were taken only in the northern part. The lagoon area is characterized by four different rates of sedimentation on the basis of four ages downcore (737 cm, 6880 cal BP;
Fig. 4. Age-depth relation according to the date of borehole samples and the resulting local relative sea-level rise, Kotihi lagoon region. It is given the relative sea level rise according to Vo¨tt (2007) for reasons of comparison (see details in the text).
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Fig. 5. Stratigraphic correlations among the defined units of the cores.
8. Evolution of Kotihi lagoon The Holocene evolution of Kotihi lagoon can be divided into three stages, based on whether the area was under transgressive, regressive, or almost stationary relative sea level conditions (Fig. 5). Relative sea-level variations are a consequence of eustatic change in sea-level and the corresponding loading effects (Lambeck, 1995), tectonic deformation (e.g. Stamatopoulos and Kontopoulos, 1994), and sediment supply from the Peneus River, which has shifted its course over the Holocene (Raphael, 1978). 8.1. Stage A (6880–3810 cal BP) Kotihi lagoon was first established on the Paleo-Peneus delta plain earlier than 7000 BP. At this time, the rate of world sea level rise began to diminish (Lambeck, 1995). From this time to about 3810 cal BP (base of Unit VII) core KK penetrated relatively uniform
lagoonal bottom facies, with two minor episodes of greater stream influence. Thus, during this stage (from Neolithic to Early Bronze Age) lagoonal sedimentation appears to have approximately kept pace with rising sea level, so that the relative position of the lagoon remained stationary. 8.2. Stage B (3810–1400 BP) In units VII–IX in core KK, the facies change from lagoonal with plant material to marginal and then to full terrestrial. This facies sequence marks a regressive stage, probably as a result of deltaic progradation. This interval is dated from about 3810 to 1400 cal BP (?) on the basis of bounding radiocarbon and interpolated dates. There is a controversy about the reasons that caused the Mediterranean soil erosion during the Holocene. Some workers supported the idea of a dominant anthropogenic cause for this erosion (e.g., Pope and van Andel, 1984; Bru¨ckner, 1986, 1997, 1998; Cherry
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Fig. 6. Geographic maps of the 16th, 17th and 18th centuries indicate that the Peneus River mouth migrated between the two capes of Kyllini peninsula (National Bank of Greece Cultural Foundation, 2006).
et al., 1988; Van Andel et al., 1990; Fuchs, 2007). Others have attributed this erosion to climate factors (Vita-Vinzi 1969, 1976; Bintliff 1975, 1977, 1982). Bintliff (2002) and Pope et al. (2003) considered both the climatic and anthropogenic impact as causes of the Holocene erosion. Lespez (2003) and Fuchs (2007) suggest that only the human impact on the landscape results in accentuated soil erosion. Furthermore, Fuchs (2007) distinguishes four phases of strong erosion in southern Greece: a. Middle and Late Neolithic phase. b. Middle–Late Bronze phase. c. Classical/Roman phase and d. Ottoman phase. The stage B appears to belong to b and c phases. 8.3. Stage C (1400–present) In Unit X of core KK, the facies change from full terrestrial to marginal river flood deposits. This change is probably dated at 1400 BP and suggests the beginning of a transgressive period. In the same time interval in core K, sand dune subfacies of Unit I pass
upward into washover fan subfacies of Unit I and then into mud flat of Unit II (1150–395 cal BP). Thus in both cores, this stage is characterized by the effects of marine transgression. The landward migration of the coast probably is the result of the avulsion of the Peneus River to the south of the Kyllini peninsula (Fig. 1), cutting off sediment supply by a longshore drift. This shift in the Peneus River was probably the result of tectonic tilting marked by strong and destructive earthquakes during the 4th–6th century A.D. (Pirazzoli, 1986; Mouyaris, 1994; Stiros, 2001). In core K, from 395 cal BP to present, the facies change in succession from lagoonal (Unit III), beach (Unit IV), washover (Unit V) and sand dune (Unit VI). This sequence of facies corresponds to a retreat of the coastline. The rate of sedimentation was about 0.52 cm/a after 150 cal PB. This value is identical with that suggested by Bouzos and Kontopoulos (1998) due to the agriculture and the small streams that debouched into the lagoon. Fuchs (2007) refers a high rate of sedimentation from the middle Ottoman period until present times.
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9. Discussion The Kotihi lagoon existed in its present position at least from 7000 years ago. The Kraft’s borehole P15 has a core interval only 3 m below the surface and the base of this interval consists of a peat, corresponding to unit VII, and probably has formed on a sand or mud flat of the lagoonal margin. If borehole P15 was deeper then its core profile would be similar with the KK borehole profile. Kraft et al. (2005) suggested a Neolithic and Helladic coastline 2.7 km east of the present Kotihi lagoon. According to this suggestion, the Neolithic lobate Peneus River delta was established on this paleo-coast and the Kotihi barrier island developed by a longshore spit. Raphael (1978) concluded that this coastal area shows three events of coastal progradation during Hellenistic (4th–2nd cent. BC), Roman and early Medieval times (2nd cent. BC–6th cent. AD) and one event of coastal retreat during Turkish times (15th–18th cent. AD). This study not only suggests a coastal progradation during the Hellenistic, Roman and early Medieval times but also throughout the two last millennium BC. This progradation would have created the most seaward beach ridge approximately 1.2 km offshore (Raphael, 1978). Raphael (1973) reports a minimum age of the most landward beach ridge at 2300 BP. During the Dark Ages (600–900 AD), the Middle Byzantine Period (900–1261 AD) and the Frankish Period (1261–1453 AD), the coast retreated. Raphael (1978) reports that the second levee in the Turkish period, standing well above the flood plain at the shoreline, indicates that the shore has retreated from the Middle Ages. This probably suggests an avulsion of the Peneus River to south of the Kyllini peninsula (Fig. 1), thus cutting off sediment supply by a longshore drift. Geographic maps of the 16th, 17th and 18th centuries indicate that the Peneus River mouth migrated between the two capes of Kyllini peninsula (Fig. 6) (National Bank of Greece Cultural Foundation, 2006). During the Ottoman Period (1460–1827 AD) and Modern times (1827 AD– present) the coast retreated in its present position. 10. Conclusions Core stratigraphy and radiocarbon data define three stages in the evolution of Kotihi lagoon on the basis of the rate of relative sea level changes and the rate of sedimentation. During the first stage, from earlier than 7000 BP to 3810 cal BP, there was a balance between the rate of relative sea level change and the rate of sedimentation, as sea level continued to rise. In the second stage, from 3810 to 1400 cal BP (?), the rate of sedimentation was higher from the rate of relative sea level change, probably because of proximity of the mouth of the Peneus River and the high rates of sediment supply. In the third stage, from 1400 BP (?) to present, the landward migration of the coast was probably the result of the avulsion of the Peneus River. Acknowledgements We wish to thank Dr. D.J.W. Piper (Bedford Institute of Oceanography, Canada) for his useful suggestions and comments on the manuscript. We wish to acknowledge Dr. D.B. Scott (University of Dalhousie) who examined some samples for ostracodes and foraminifera. The research was funded by research committee of University of Patras, Grant FK2441. References Avramidis, P., Bouzos, D., Antoniou, V., Kontopoulos, N., 2008. Application of grain size trend analysis and spatio-temporal changes of sedimentation, a tool for lagoon management. Case study: the Kotychi lagoon (western Greece). Geologica Carpathica 59 (3), 261–268. Bintliff, J.L., 1975. Mediterranean alluviation: new evidence from archaeology. Proceedings of the Prehistoric Society 41, 78–84. Bintliff, J., 1977. Natural environment and human settlement in Greece. In: British Archaeological Reports, vol. 28. British Archaeological Museum, Oxford.
Bintliff, J., 1982. Paleoclimatic modelling of environmental changes in the East Mediterranean region since the last glaciation. In: Bintliff, J.L., van Zeist, W. (Eds.), Paleoclimates, Paleoenvironments and Human Communities in the Eastern Mediterranean Region in Later Prehistory. British Archaeological Reports, International Series, Oxford, 133 pp. Bintliff, J., 2002. Time, process and catastrophism in the study of Mediterranean alluvial history: a review. World Archaeology 33, 417–435. Bird, E., 1985. Coastline Changes. A Global Review. J.Wiley and Sons, Chichester, 219 pp. Bouzos, D., Kontopoulos, N., 1998. Recent sedimentation in the lagoons of the western Greece. Example the Kotihi lagoon. Bulletin of the Geological Society of Greece XXXII (2), 237–245. Bouzos, D., Kontopoulos, N., 2004. Oceanographic observations in the lagoon of Kotihi (W Peloponnesus). In: Seventh Panhellinic Geographical Conference of the Hellenic Geographical Society. Proceedings, vol. 1, pp. 340–347. Bru¨ckner, H., 1986. Man’s impact on the evolution of the physical environment in the Mediterranean region in historical times. GeoJournal 13, 7–17. Bru¨ckner, H., 1997. Coastal changes in western Turkey: rapid delta progradation in historical times. In: Briand, F., Maldonado, A. (Eds.), Transformations and Evolution of the Mediterranean Coastline. CIESM Science Series, vol. 3, pp. 63–74. Bru¨ckner, H., 1998. Coastal research and geoarchaeology in the Mediterranean region. In: Kelletat, D. (Ed.), German Geographical Coastal Research: the Last Decade. Institute for Scientific Cooperation, Tu¨bingen, pp. 235–257. Cherry, J.F., Davis, J.L., Demitrack, A., Mantzourani, E., Strasser, T.F., Talalay, L.E., 1988. Archaeological survey in an artifact-rich landscape: a middle Neolithic example from Nemea, Greece. American Journal of Archaeology 92, 159–176. Fuchs, M., 2007. An assessment of human versus climatic impacts on Holocene soil erosion in NE Peloponnesus, Greece. Quaternary Research 67, 349–356. Gaudette, H., Flight, W., Toner, L., Folger, D., 1974. An inexpensive titration method for the determination of organic carbon in recent sediments. Journal of Sedimentary Petrology 44, 249–253. Kokkalas, S., Xypolias, P., Koukouvelas, I., 2008. Surface ruptures of the recent Mw 6.3 (June 08, 2008) earthquake event in the northwestern Peloponnese: preliminaryfieldreport. http://www.emsc-csem.org/Doc/20080608_GREECE/Surface_ ruptures.pdf. Kraft, J.C., RappRip, G., Gifford, J.A., Aschenbrenner, S.E., 2005. Coastal change and Archaeological setting in Elis. Hesperia 74, 1–39. Lambeck, K., 1995. Late Pleistocene and Holocene sea-level change in Greece and south-western Turkey: a separation of eustatic, isostatic and tectonic contributions. Geophysical Journal International 122, 1022–1044. Lekkas, E., Papanikolaou, D., Fountoulis, I., 1992. Pyrgos and Tropaea. Neotectonic map of Greece, at scale 1/100,000. Earthquake Planning and Protection Organization, unpublished. Lespez, L., 2003. Geomorphic responses to long-term land use changes in Eastern Macedonia (Greece). Catena 51, 181–208. Mouyaris, N., 1994. Seismic history of the Aegean area. Unpublished PhD thesis, University of Patras, Patras, Greece (in Greek language with English abstract). National Bank of Greece Cultural Foundation, 2006. The Peloponnesus Cartography and History. 16th–18th century. NBGCF, Athens, 197 pp. Pirazzoli, P.A., 1986. The early Byzantine tectonic paroxysm. Zeitschrift fu¨r Geomorphologie 62 (Suppl.), 31–49. Pope, K.O., van Andel, T.H., 1984. Late Quaternary alluviation and soil formation in the Southern Argolid: its history, causes and archaeological implications. Journal of Archaeological Science 11, 281–306. Pope, R.J.J., Wilkinson, K.N., Millington, A.C., 2003. Human and climatic impact on Late Quaternary deposition in the Sparta Basin Piedmont: evidence from alluvial fan systems. Geoarchaeology 18, 685–724. Raphael, C.N., 1973. Late Quaternary changes in coastal Elis, Greece. Geographical Review 63, 73–89. Raphael, C.N., 1978. The erosional history of the plain of Elis in the Peloponnesus. In: Brice, W.C. (Ed.), The Environmental History of the Near and Middle East Since the Last Ice Age. Academic Press, London, pp. 51–66. Scott, D.B., Piper, D.J.W., Panagos, A.G., 1979. Recent salt marsh and intertidal mudflat foraminifera from the western coast of Greece. Rivista Italiana di Paleontologia 85, 243–266. Shepard, F.P., Moore, D.G., 1954. Sedimentary environments differentiated by coarse-fraction studies. AAPG Bulletin 38 (8), 1792–1802. Stamatopoulos, L., Kontopoulos, N., 1994. Geomorphology and evolution of the region between Lapa and Eleotopos, NW Peloponnesus, Greece. Il Quaternario 7 (2b), 537–544. Stiros, S.C., 2001. The AD 365 Crete earthquake and possible seismic clustering during the fourth to sixth centuries AD in the Eastern Mediterranean: a review of historical and archaeological data. Journal of Structural Geology 23, 545–562. Stuiver, M., Reiner, P.J., Bard, E., Beck, J.W., Burr, G.S., Hughen, K.A., Kromer, B., Mc Cormac, G., Van der Plicht, J., Spurk, M., 1998. INTCAL 98 radiocarbon age calibration. Radiocarbon 40 (3), 1041–1083. Talma, A.S., Vogel, J.C., 1993. A simplified approach to calibrating C14 dates. Radiocarbon 65 (2), 317–322. Van Andel, T.H., Zangger, E., Demitrack, A., 1990. Land use and soil erosion in prehistoric and historical Greece. Journal of Field Archaeology 17, 379–396. Vo¨tt, A., 2007. Relative sea level changes and regional tectonic evolution of seven coastal areas in NW Greece since the mid-Holocene. Quaternary Science Reviews 26 (7–8), 894–919. Vita-Vinzi, C., 1969. The Mediterranean Valleys. University Press, New York. Vita-Vinzi, C., 1976. Diachronism in old World alluvial sequences. Nature, 263 pp.