Bogwood, or morta, which appears several times in Ulysses as "bogoak," is wood that has been buried in peat bogs for millennia. Anaerobic conditions preserve the wood, and its tannins combine with iron dissolved in the acidic water to stain it darker and darker as time goes on, in a process that eventually leads to pure blackness and coal-like petrification.

John Hunt 2015

A piece of Irish bogoak that has been sawed and sanded, but not stained. The heartwood lies at the top. Source:

Irish farmers excavating an oak tree from a peat bog. Source: