Grasping Reality on TypePad, by Brad DeLong

...Attempts to equate the graphs of wrecks over time with fluctuations in maritime trade rest on two fundamental assumptions:

1. The probability that any voyage will end in wreck is the same at all periods.

2. Wrecks are equally visible archaeologically at all periods....

Shipwrecks are found, usually by SCUBA divers in relatively shallow coastal waters, because they show up as a mound of cargo on the seabed, or, in the case of early modern wrecks, the iron cannon.... Ships are therefore unlikely to be found if they were carrying largely non-durable cargo, like slaves, grain, textiles, or other perishables in sacks. The main durable cargoes likely to preserve ancient shipwrecks are therefore cargoes of stone, or of goods carried in amphorae.... The ‘wreck’ graphs may therefore be considered as graphs of known cargoes. Are they in fact primarily graphs of amphora usage? By the Medieval period, at least in the central and western Mediterranean, the barrel had largely replaced the amphora as the preferred transport container for liquids and even some solid goods, such as salted fish, having a better volume to weight ratio, more efficient stacking capability, and greater manoeuvrability on land....

We cannot be entirely confident that either the second-century or the early Medieval decline in trade was as sudden or complete as the graphs would seem to suggest. The real question is when this shift in container technology commenced, and how fast it occurred....

Barrels... Celtic origin... referred to in literary sources from the second half of the first century BC... known archaeologically... along the Rhine frontier from the late first century BC..... By the late third or early fourth century AD the tariffs for unloading and handling wine brought down the Tiber to Rome’s river port... specify charges per barrel; there is no mention of amphorae.... Is part of the apparent sharp drop in the shipwreck graph from the first to the second century AD due to an increasing use of barrels? But if so, it can hardly account for all of it—amphora usage in the Mediterranean remained common until the sixth or seventh centuries....

Examination of the relatively small number of 87 Roman and Byzantine wrecks carrying stone cargoes gives a rather different picture chronologically and reinforces the idea that the shape of the main wreck graph is heavily influenced by chronological fashions in amphora usage, rather than necessarily being representative of all shipping....

The picture of Mediterranean trade suggested by finds on land certainly does not suggest a downturn of maritime trade in the early second century.16 From the Augustan period through to the mid-first century AD, Italian Terra Sigillata pottery achieved a wide distribution throughout the Mediterranean, and was even exported to India. From the early first century AD onwards it was increasingly replaced by Gaulish Samian ware, the distribution of which centred on the central and western Mediterranean. From around AD 90 African Red Slip ware began to be exported in quantity from Africa Proconsularis (modern Tunisia) and rapidly became the dominant Roman fineware class in the western and central Mediterranean, achieving a pan-Mediterranean distribution from the third to seventh centuries AD....

The end of this intensive, connected trading system has been a matter for prolonged debate. Pirenne considered that Mediterranean long-distance trade continued essentially unchanged until the Arab expansion of the seventh century;18 Hodges and Whitehouse showed that this view was based on an optimistic reading of the documentary sources, and that archaeological evidence suggested a steep decline in trade in the western Mediterranean in the sixth century, a view largely supported by more recent analyses.... The ceramic evidence from land sites shows that the seventh century generally saw a further major downturn in the already diminishing volume of maritime trade, especially in the west and central Mediterranean. Following the Arab invasions of North Africa in the 640s, exports of African Red Slip ware dwindled and ultimately ceased by the time of the final conquest of North Africa at the end of the seventh century....

During the period 100 BC to AD 300 we find wrecks of ships that carried cargoes of well over 100 tons, even over 350 tons, which we do not before about 100 BC or between AD 400 and 1000.29 The attestation in wrecks of shipping of this size is important in the perspective of the longue durée, suggesting that the intensity and volume of Roman trade was such as to justify investment in larger merchant ships (and, as we shall see, of the harbour infrastructure to receive them) than was the case in the Classical or early Hellenistic periods, or in the early Middle Ages...

#economichistory #history #noted #2019-10-04