A muddy tyre track

A tyre track is an indexical mark of a wheel. It contains information about the referent (the wheel’s outline and tread mark pattern). It also contains information from the world beyond the referent (the person on the bike, the direction in which they were travelling from and to). Having been made in a soft, thick, clay-y medium it is also a trace of the weight of the rider and the speed of travel. It indexes physical properties as well as visual ones, properties of the referent and of the indexical medium itself (the wetness of the mud).

But this particular wet mud is more than just a lump of soft clay. It is situated in nature and so is subject to rainstorms or dry spells - its softness will vary over time. The mud might become baked in the sun, solidifying the track mark into a kind of fossilised mould of the tyre - a lasting index. But it might also become submerged, liquifying any recognisable mark or walked over by other treads that will render its mark invisible under their own. The index inside this wet, soft, malleable, changeable, uncertain medium is ephemeral, and thus it exudes a sense of recency. As I walk through the forest, and look down at this tyre mark, I know it was not long ago that the rider also passed through here.

A cast still in its mould

Krauss speaks of the index as being ‘physically present but temporally remote’ - that it is ‘produced by a physical cause that is no longer present in the given sign’.21 Might it be possible for the physical cause to remain present? And how might that happen without it occluding the indexical trace it makes? It is difcult to imagine how this might work - in the realm of, say, a fngerprint - after all we cannot see the print until the fnger has moved away.

An obvious solution is simply to just not move the referent too far away, to keep it in view. A cast shown alongside its mould, for example. But this requires a shift - even if a small one. When the cast is presented still inside its mould, a physical contact remains between the index and its referent. The action of making the indexical mark remains present in time. But then we reintroduce the problem of occlusion. Our view of the moulding surface becomes blocked by the cast - we cannot see the indexical surfaces themselves, only the process by which the index is being, or has been, created. Temporally present then, but not quite physically, at least not visibly so. Krauss’ paradox of physical presence with temporal absence, remains.