What type of clue are recorded signatures on a summit log identified as?

Recorded signatures on a summit log are considered written evidence because they consist of an individual's name or unique mark that is documented in a legible format. This type of evidence is crucial in search and rescue operations, as it can help establish the presence of individuals at a specific location (the summit) and can indicate whether they have completed an ascent. Written evidence such as signatures serves as an official record, providing names, dates, and possibly conditions of the climbers, which can be essential in determining search efforts and timelines.

In contrast, other forms of evidence like physical or visual evidence rely on tangible items or observable features rather than documentation through writing, which distinguishes written evidence as a specific and important category in investigations.