Hello,

I'm working on the oldest commercial coal mines in the USA in the
Richmond Coal Basin at Midlothian, Virginia. They started in 1699 and
continued through to about 1932. The most intensive use was from about
1750 to 1865. The mines are a veritable "mountains of the moon"
landscape with holes, tailings heaps, railroads and other features
overlapped on 155 acres. The larger holes are up to 50 feet wide, none
has a bottom now deeper than 15 feet due to time and infilling and
caving. There are also a forest of smaller holes, usually about 10 feet
total diameter, including the upwelled ring of material around the
mouth. The mouths of these smaller ones are about 4 feet in diameter.
They are usually about 3 feet in depth. The problem is that none of
these complexes has been contour mapped and then interpreted. What
little mapping there is consists of a single point reading transposed
onto a 5' county contour map which shows vastly insufficient detail to
be useful.

These smallest holes are the subject of my question. I am working on
the assumption that they are ventilation shafts and were dug from the
bottom upward. The way these mines worked, from historical and Richmond
Basin specific descriptions by ex-pat English and Scots engineers, is
that typically a 7x14' hole was dug, half was left open for ventilation
and the other half was used for moving coal and people. A fire was lit
at the bottom of the open shaft and air was pulled down the vent
shafts, across the galleries and up the exhaust hole. Methane was
plentiful and caused all sorts of problems and catastrophes.

The small holes looked at from the side resemble a giant do-nut cut in
half the long way and laid on the ground. The body of the do-nut is the
slight upwelling of spoil. Most have coal rock spoil on them indicating
that the last materials out were very near the coal beds. The hole of
the donut is a cone shaped hole, none of which are over 3 feet deep.

Would I be correct in interpreting them as vent shafts? On the few
plans I have seen on relatively uncomplicated areas, they appear to
ring the larger shafts. Would I also be correct in assuming them to
have been dug from the bottom up? They occur isolated somewhat from the
nearest larger hole and never have more than a very slight upwelled
ring around the edge which I assume would keep most of the runoff water
out of them. I have also seen them next to streams which would flood
under our torrential semi-tropical downpours in the summers.

Any thoughts gratefully received. I've looked at Diderot and De Re
Metallica and a few others and have not found them helpful for this
problem.

Lyle Browning


Without stratigraphy, there is no archaeology.