Protection in wall two is stronger at the boundaries where annual rings meet.
It has been dated by drilling a core sample and counting the annual rings and was considered to be 4,844 years old in 2012.
Long Island's development can quite nearly be recorded in the annual rings in their trunks.
The annual rings of growth are for many years quite wide, but later they become narrower and narrower.
This is equivalent to 8.7 annual rings per centimetre of core, said to be half the commonly quoted figure for growth rate.
Termites usually eat only the soft part of wood, leaving the annual rings intact.
In species with annual rings, these rings can be counted to find the age of the tree.
The presence of the dark lines is similar to the annual rings on a tree.
That results in boards with the annual rings mostly perpendicular to the faces.
Dendrochronology, the dating and study of annual rings in trees.