oxides or the like either before or after compacting the shale with reference to fig1 and 2 the following example will serve to illustrate this invention by describing the development of a small region 10 of an oil shale deposit which may be performed in successive stages to recover shale oil in other regions of the deposit the shale deposit lies below 300 feet of overburden and has a thickness of 120 feet the shale contains enough kerogen to provide a fischer assay richness of 30 gallons of hydrocarbons per ton of shale rock region 10 has a horizontal dimension of 120 by 40 feet and has a vertical dimension of 120 feet zones 13 14 and 15 are each 40 feet square in horizontal dimension and 120 feet in depth initially the bottom 24 feet of zone 13 is removed by conventional mining techniques through access drifts not shown in the figures the mined material is removed to the surface for surface retorting drill holes are placed in the remaining zone 13 shale in a pattern which will obtain the desired particle size distribution and permeability explosive charges are loaded in these holes and the charges are detonated progressively from the bottom up following the explosive caving both product recovering and air feeding facilities are installed gas flow through the.