A coal containing formation may be treated using an in situ thermal
process. A mixture of hydrocarbons, H.sub.2, and/or other formation
fluids may be produced from the formation. Heat may be applied to the
formation to raise a temperature of a portion of the formation to a
pyrolysis temperature. Heat sources within a relatively thin layer of
coal may be positioned in a staggered pattern near to edges of the layer
so that superposition of heat from the heat sources allows a large
percentage of the layer to reach a desired temperature.