Late Holocene Paleogeography of the Coastal Plain of the Gulf of Messenia, Greece, and Its Relationships to Archaeological Settings and Coastal Change
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Late Holocene Paleogeography of the Coastal Plain of the Gulf of Messenia, Greece, and Its Relationships to Archaeological Settings and Coastal Change JOHN C. KRAFT Department of Geology, University of Delaware, Newark, Delaware 19711 GEORGE RAPP, JR. Department of Geology and Geophysics, University of Minnesota, Minneapolis, Minnesota 55455, and Hellenic Institute of Oceanographic and Fishing Research, Agios Kosmas, Ellinikon, Athens, Greece STANLEY E. ASCHENBRENNER Minnesota Messenia Expedition, Department of Geology and Geophysics, University of Minnesota, Minneapolis, Minnesota 55455 ABSTRACT INTRODUCTION made that current geomorphic elements have existed from middle Holocene time to The coastal plain of the Pamisos River The late Holocene geologic history of the the present. Despite extensive discussion in and five associated rivers at the head of the world's sandy coastal plains undoubtedly the literature of the interplay between cul- Gulf of Messenia in the southwestern played a significant role in their occupancy tural and physical phenomena since Peloponnese includes middle through upper by man. These plains are loci of relatively Neolithic time, a true synthesis of these Holocene sedimentary-environment litho- rapid geographic change, so there is a po- elements has been exceedingly difficult to somes of alluvial flood-plain deposits, tential for large error if the assumption is achieve. In addition to a lack of adequate channel sand, braided streams and deltas, bank swamps and marshes, dune fields, minor lagoons, beach-accretion ridges, and shallow-marine sediment. The areal dis- tribution of these environments is in bal- ance between the sediment supplied by the alluvial systems and their modification by coastal wave action. Questions remain about the importance of tectonic uplift and downwarp relative to sediment input and changes in eustatic sea level. Radiocarbon and pottery dates, drill cores, outcrops, and environmental studies have provided in- formation for the development of a syn- thesis of paleogeographic change and its re- lationship to archaeological remains from the Neolithic period (middle Holocene) to the present. Examples include (1) a marine embayment extended into the area of the present Pamisos River flood plain near the town of Messini in middle late Holocene (Neolithic-Helladic) time, (2) rounded hills flanking the low-lying Karya River coastal plain were wave-cut cliffs in pre- Roman time, (3) the lower Karya River valley, now occupied by a braided stream, was a swampy lagoonal area, (4) major Early Helladic buildings at Akovitika were constructed along a shoreline, whereas the site is now surrounded by backswamp, and (5) the post-Roman delta-coastal plain of the Tsana River is now undergoing intense erosion. These types of paleogeographic analyses may prove of use to archaeologists in understanding the reasons for selection of habitation sites. They may also assist the modern occupants of the coastal area in coastal planning and in understanding rates and nature of coastal change at the head of the Messenian embayment. Key words: Figure 1. Index map of southern Greece, showing areas of Quaternary sedimentary strata (striped), mainly Holocene at surface but with Pleistocene subsurface elements at heads of gulfs and embay- sedimentology, geomorphology. ments and in interior drainage basins. Geological Society of America Bulletin, v. 86, p. 1191-1208, 21 figs., September 1975, Doc. no. 50902. 1191 Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/86/9/1191/3418247/i0016-7606-86-9-1191.pdf by guest on 30 September 2021 1192 LATE HOLOCENE PALEOGEOGRAPHY OF COASTAL PLAIN, GULF OF MESSENIA, GREECE daring to correlate geomorphic-climatic provide useful models for projection into The coasts of Greece are an area in which arid cultural events, it now appears evident the geologic past. Major advances in com- study of paleogeographic detail can benefit that attempts to project geomorphic- prehension of the nature of coastal change scholars from several disciplines, and in climatic events from one geographic prov- in late Holocene time must be a product of which accurate archaeological dates can be ince to another are not likely to be success- interdisciplinary studies. Past studies often used effectively (Fig. 1). The writings of an- ful, since climatic change is frequently a combined elements of geomorphic or cient authors such as Pausanias, Herodotus, provincial event and cannot be extrapo- geologic reasoning but ignored meteorol- Strabo, and Aristotle frequently refer to lated world-wide. A related problem is the ogy, archaeology, and other disciplines. We geomorphic and environmental changes influence of eustatic versus local sea-level firmly believe that future advances in that have affected the geography and his- fluctuations on cultures associated with paleogeographic and paleoenvironmental tory of the Aegean area. These references coastal-plain and maritime environments. reconstruction lie in the interfaces between have been used sporadically by historians Successful solution of such problems re- and not in the cores of the separate discip- and archaeologists in attempts to show quires a measure of short-term and long- lines. paleoclimatic and, more rarely, paleogeo- term geomorphic change. Fortunately, the The rate of rise of sea level either greatly graphic conditions in late Holocene time in sedimentary records of river and coastal diminished or ceased at the end of Early the eastern Mediterranean. plains, deltas, and shallow-marine deposits Helladic time (middle to late Holocene In the past 20 years, a wealth of data, re- provide such a measure. These records hold time). The effect upon the world's coastal search techniques, and concepts of en- the clues to paleogeographic interpretation environments and coastal morphology vironmental analysis have been directed to and rates of geographic change requisite for must have been severe. The effects on cul- the interpretation of paleoenvironments in paleoenvironmental and paleogeographic tures oriented to previous morphologic and the Mediterranean area, but in general they reconstructions. climatic conditions may have led to the have been limited to surface geomorphic Reconstructions of the late Holocene en- need for reorientation of ways of life as well studies. Some attempts have been made to vironment are of immense use to historians, as of location of building sites and arable relate geomorphic setting to climatic archaeologists, and civil engineers. They lands. change, in the form of paleoclimatic studies based upon pollen analysis and upon analysis of historical records. Attempts Figure 2. Potential elements of marine transgression 3/ REGIONAL CLIMATIC CHANCE have been made to explain the rise and fall MORE EROSION • REGRESSION of civilizations by change in both historical or regression, showing eight variables that might affect LESS EROSION - STABILIZATION OR TRANSGRESSION stability of coastal position in sedimentary and environmental factors, the ultimate continental-shelf—coastal-plain setting. goal being to relate historic events to geomorphic-climatic and man-made causes. 0/ DEFORESTATION AND OTHER 7/ TECTONIC UPLIFT OR Although Carpenter (1966) proposed VEGETATION COVER CHANCES"V«./ DOWNKARP OF that a sequence of cyclic climatic events had ERODING AREA i/CrcLIC STORK TRACK a dominating effect on the rise and fall of SHIFT • »AVE CHARACTER UPLIFT-MORE SEDIMENT- CHANGE • TRANSGRESSION REGRESSION Mediterranean civilizations, analyses of the OR REGRESSION OOWNWARP - LESS pollen record (Wright, 1961, 1968, 1969) SEDIMENT-TRANSGRESSION do not appear to confirm cyclic climatic in- TRANSGRESSION • f terpretations of middle or late Holocene environmental change. 1/ EUSTATIC CHANGE IN Detailed study of pollen spectra, where SEA LEVEL available in relatively continuous Pleistocene-Holocene sections, seems to be a prerequisite for comprehension of both climatic and man-effected environmental change. Typical examples are the work of van der Hammen and others (1965) on a thick peat sequence in Macedonia and of Wright (1968) on the lagoonal muds of Osmanaga. In regard to climatic change TABLE 1. RADIOCARBON DATA AND DESCRIPTIONS OF DRILL-HOLE SAMPLES, HEAD OF GULF OF MESSENIA Location Elevation* -6C"1 Age (yr) Date Description Environment (m) 5568 5730 Corrected half-life half-life MASCA+ Grigorios Karya River +0.1 to +0.4 216 ± 9 19,555 ± 85 2,012 1,900 50 A..D . Brown to black sand Backswamp at base Zervas, 1-7084 coastal plain with plant debris of beach debris Troupakis no. 2, Karya River -3.4 to -7.0 976 ± 7 29,960 ± 2,800 30,832 28,882 B • C. Organic, finely di- Flood-plain silt 1-7086 coastal plain vided in gray silt Pamisos no. 4, Pamisos River -6.5 to -7.0 432 ± 7 4,545 ± 95 4,681 5,310 3360 B .C. Plant debris 1n Backswamp - flood sample 13, flood plain greenish-black mud plain - overlying 1-7228 and sand marine sand Pamisos no. 4, Pamisos River -15.5 to -17.3 457 ± 7 4,905 ± 95 5,052 5,660 3710 B.• C. Plant debris in Backswamp - flood samples 37 to 41, flood plain dark-gray, very plain above allu- 1-7226 fine sand vial mud Pamisos no. 3, Pamisos -2 to -2.25 278 ± 8 2,615 ± 90 2,693 2,760 810 B..C . Swamp grass in Backswamp of Aris 1-7227 flood-plain yellow-brown mud River on Pamisos backswamp flood plain * Of sample, above or below sea level. + Accordlnq to Museum of Applied Science Center for Archaeology correction of Ralph and others (1973), 1n order to closest approximate calendar years and to relate better to archaeologist-historian potential users of data herein. Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/86/9/1191/3418247/i0016-7606-86-9-1191.pdf by guest on 30 September 2021 KRAFT AND OTHERS 1193 since Mycenaean time,1 Wright (1968, ment, and that tectonic movements in the tween Osmanaga Lagoon and the Bay of p. 126) said, "It may be a fair conclusion basin are predominantly downward. Navarino. Pritchett (1965) noted that the from the pollen studies in Greece that no Flemming's "stable sea theory" allows for a mosaic was not constructed to withstand vegetational changes may be attributed ±0.5-m deviation during this period.