Abstract: Systems for heating a body of crushed hydrocarbonaceous material to produce hydrocarbons therefrom can involve heating multiple zones of the body of material sequentially. An exemplary system can include a body of crushed hydrocarbonaceous material having a lower zone and an upper zone. A lower heating conduit can be embedded in the lower zone, while an upper heating conduit is embedded in the upper zone. A collection conduit is embedded in the upper zone at a location above the upper heating conduit. A lower heating valve is also operatively associated with the lower heating conduit and is capable of switchably flowing a heat transfer fluid through the lower heating conduit. An upper heating valve is operatively associated with the upper heating conduit and capable of switchably flowing the heat transfer fluid through the upper heating conduit.