Almanac-inside-an-almanac:

February's entry is Aldo and a friend cutting down a tree. As the two-man saw moves through deeper growth rings he lists important events in the local (Wisconsin) ecology that happened that year, periodically taking breaks for the sawyers to catch their breath. 

And of course he's right: the patterns in tree rings are an index of each year's weather. We even have an International Tree-Ring Data Bank that can accurately date wood samples by matching the exact ring sequences of a given species over a period of time. A perfect record, the ultimate almanac.