Thomas F. Jorstad

Pelusium, an Ancient Port Fortress on Egypt's Nile Delta Coast: Its Evolving Environmental Setting from Foundation to Demise

Abstract This study documents the evolution of the coastal site on which an ancient port fortress, Pelusium, was positioned in the NE corner of Egypts Nile Delta. Focus is on the stratigraphy, petrology, and faunal assemblages of radiocarbon-dated core sections recovered at major ruins at the site. The late Holocene development of this margin surface is unusual in that it has been subject to important geologically recent uplift since the citys founding, in contrast to predominant subsidence and relative sea-level rise that characterize most of the delta margin west of Pelusium. Vertical tectonics resulted from displacement along the Pelusiac Line, a major structural feature several kilometers south of Pelusium. The geoarchaeological survey shows the was built with ready access to the Mediterranean, after tectonic uplift, from ∼1000 to 800 BC. It was then, when Egypt was subject to Assyrian control, that the margin evolved from an open shallow marine (prodelta, delta-front) setting to a coastal one. The citys progressive decline was influenced by warfare with Persians and other invaders from the east, effects of plague, and diminished role of its commercial and trade activities following construction of Alexandria by the Greeks. However, Pelusiums eventual demise also resulted from natural factors, especially tectonically controlled motion of the lower delta plain. Vertical shifts around 800–850 AD and subsequent periods resulted in rapid coastal build-out north of Pelusium. This caused a cutoff of the city from the sea and the Niles Pelusiac branch, the major navigational byway into the delta. Pelusium, after approximately 800–850 AD, continued as a commercial center for an additional three to four centuries prior to its abandonment by the time of the Crusades. Submergence of the city on the delta margin by rise of relative sea level has been effectively counteracted by episodic fault-related uplift of this lower plain sector and continued subaerial exposure since Byzantine time.

Alexandria, Egypt, before Alexander the Great: A multidisciplinary approach yields rich discoveries

Historic records refer to Rhakotis as a settlement on Egypt’s Mediterranean coast before Alexander the Great founded the famous Mediterranean port city of Alexandria in B.C. 332. Little is known of Rhakotis, however, because the site has yet to be clearly identified beneath the modern city. This problem motivated a geoarchaeological investigation of sediment cores from Alexandria’s East Harbor, from which radiocarbon-dated sections of pre-Alexander age (>2300 yr B.P.) have been obtained for study. These core sections comprise a number of critical components, five of which are emphasized here: ceramics, rock fragments derived from Middle and Upper Egypt, and sediment with markedly increased contents of lead, heavy minerals, and organic matter. A multidisciplinary approach, by which archaeological, stratigraphical, petrological, and geochemical methodologies are applied to study the five distinct core components, reaffirms that a sum can be greater than its parts. Together, the diverse markers in the dated core sections enable us to confirm human activity to at least seven centuries before B.C. 332 on the mainland coast, where Alexandria would later be established. Alexander’s city, it now appears, rose from a preexisting town whose inhabitants had long before recognized the favorable harbor potential of this Egyptian coastal sector. The discoveries, providing direct evidence of the settlement’s early (to ca. B.C. 1000) existence, are intended to prompt new exploratory efforts on land and offshore to further delineate that center’s actual position and history.

Predynastic human presence discovered by core drilling at the northern Nile delta coast, Egypt

A small but significant find made during a geological survey provides evidence of the oldest human presence yet discovered along the northernmost margin of Egypt9s Nile delta. A manuport, a rock fragment carried by human agency to the site, was discovered in a sediment core section north of Burullus lagoon near the Mediterranean coast. Accelerator mass spectrometry (AMS) radiocarbon analysis of plant-rich matter in the mud surrounding the object provides a date calibrated to 3350–3020 B.C., the late Predynastic period. This long thin manuport, formed of dolomite, had not been deposited by the Nile or the sea but was collected and transported from an outcrop exposure positioned at least 160 km south of the core site. The fragile manuport, used for an undetermined function, lay buried at a depth of 7.4 m in dark olive gray mud deposited in a shallow brackish lagoon setting close to a marsh. This fortuitous find documents an early human presence in the middle Holocene wetlands along the delta9s paleocoast, a sector where traditional excavation and augering are normally incapable of reaching occupation levels or zones of activity at considerable subsurface depths. Core drilling provides a means to help archaeologists locate undetected and potentially important sites.

Direct Sediment Dispersal from Mountain to Shore, with Bypassing via Three Human-Modified Channel Systems to Lake Annecy, SE France

Abstract Lake Annecy in Haute Savoie, France, receives about two-thirds of its fluvial input from three rivers that flow to its southern end-point. The channels of the Eau Morte, Ire, and Bornette rivers are almost completely channelized in their lower reaches as a result of human activity, with flow contained along parallel, but separate, paths from headlands in the proximal drainage basin directly to the lake. Petrographic data from river samples collected in this study serve to differentiate sand-size material carried by each fluvial system. Proportions of the dominant (limestone) and five additional (dolomite, quartz, gypsum, rock fragments, and ‘other’) components in the 3 rivers are more closely related to source supply than to fluvial transport effects or sampling strategy. Of the 7 components, mica best records the influence of depositional mechanisms. Much of the carbonate sand and coarser material at the lake shore is derived from widespread Mesozoic outcrops. Non-carbonate sand input, partially resulting from erosion of glacial till deposits and pedogenic horizons in the southern drainage basin, provides key compositional markers to differentiate between sediment carried to the lake by each river. Until several centuries ago, deposits of the Eau Morte, Ire, and Bornette flowed to the Bou du Lac, and formed a merged, multifluvial lacustrine delta. As drainage and channel containment projects related to agricultural development intensified in lake margin lowlands, the 3 channels were separated on the delta surface, allowing bypass of river material directly onto subaqueous deltas in the lake. Specific mineral assemblages, especially quartz, mica and rock fragments, may prove useful as key tracers of human-altered sediment between the margin and deeper lake sectors.