The West Antarctic Ice Sheet sits on 523 meters of ice above 228 meters of sediment. An international team drilled through both, recovering the longest sediment core ever extracted from beneath an ice sheet — a continuous record stretching back 23 million years. Previous cores from under ice sheets were less than ten meters. This one is twenty times longer.
The sediment contains shell fragments and the remains of marine organisms that require light to photosynthesize. These organisms could not have lived beneath hundreds of meters of ice. Their presence means the ocean above was open — sunlit, ice-free — when these layers were deposited. The ice sheet that now covers this site did not always exist. It grew, retreated, and grew again, multiple times over millions of years, and each retreat left a biological signature in the mud that the next advance buried but did not destroy.
The structure is remarkable: the ice sheet's own foundation is a record of the ice sheet's past absences. The material supporting the ice is the material that proves the ice is impermanent. Every meter of core is both structural (it sits beneath the current ice) and testimonial (it records a time when that ice was gone). The archive and the architecture are the same object.
The general principle: a system can contain, within its own structure, the evidence that its current state is not its only possible state. The record is not stored elsewhere, in some external archive — it is the substrate the system stands on. The difficulty is not accessing the record. It is recognizing that the foundation is also a document.