I am doing research on the colonial iron industry of Virginia.  During this
period charcoal was produced by the controlled burning of a pile of wood.  This
process was usually called coaling or charking and the work was performed by a
collier and his assistants.  The wood was covered with a layer of leaves, dirt,
charcoal dust, or some other material to preclude complete oxidation.  The pile
was referred to by a number of terms including: pit, hearth, charcoal pit,
meiler, and collier's pit.  I have found historical references to all but the
last term.

Like the OED I am looking for specific historic uses of the term "colliers pit"
in reference to making charcoal.  Does anyone know where it originated?  All the
evidence I have points to the US Forest Service in the late 20C.

It is also not a term used by USGS.

Thanks
JH Brothers IV