Reading a Shipwreck

A wreck preserves something a settlement almost never does: a single moment. A town is built, rebuilt and cleared over centuries, and its rubbish accumulates from thousands of unrelated days, so that an object found on one floor may be older or younger than the one beside it by a lifetime. A ship that sank on a Tuesday holds the cargo, the tools and the meal of that Tuesday, sealed together at the moment the water closed over them.

[A] The advantage comes at a price that is easy to overlook. [B] A cargo is not a sample of what a society made or used; it is a sample of what was worth carrying by sea, which is a narrower and much stranger category. [C] Heavy goods of low value never travelled far, and the wrecks accordingly over-report wine, metal and fine pottery while saying almost nothing about the timber, grain and cloth that occupied most people most of the time. [D] There is a second distortion. A ship that arrived safely left no deposit at all, so the surviving record is drawn entirely from voyages that failed, and failure was commoner on certain routes, in certain seasons and with certain kinds of vessel. What looks like a picture of ancient trade is in part a picture of ancient shipwreck.