Bog-wood, also known as abonos and morta, especially amongst pipesmokers, is a material from trees that have been buried in peat bogs and preserved from decay by the acidic and anaerobic bog conditions, sometimes for hundreds or even thousands of years. The wood is usually stained brown by tannins dissolved in the acidic water. Bog-wood represents the early stages in the fossilisation of wood, with further stages ultimately forming lignite and coal over a period of many millions of years. Bog-wood may come from any tree species naturally growing near or in bogs, including oak (Quercus – "bog oak"), pine (Pinus), yew (Taxus), swamp cypress (Taxodium) and kauri (Agathis). Bog-wood is often removed from fields etc. and placed in clearance cairns. It is a rare form of timber that is "comparable to some of the world's most expensive tropical hardwoods".
Soils that are mostly wet, sandy, gravel and clay-like -- usually found above high underground waters -- are the most suitable habitats for oak forest. These forests thrive best on lowland and slight upland soils of the diluvial geological era, the valleys of river basins being especially suitable sites for this type of oak.
Variations in the water level, floods, marshes formation promote the growth of oak trees. Because of a continuous change of the direction of the river flow on a greater or lesser degree, the mainstreams weave through the valleys constantly forming live meanders. In its meandering course, the river undermines the banks covered with trees, which fall into the river and are swept away in the water. When the trunk gets trapped by its branches and roots in the river bed, over time layers of mud, sand and gravel cover it. Deprived of oxygen the wood undergoes the process of fossilization and a long process of morta formation. (Full article...)