The only bedrock exposures occur at Khakhea (Lamont,1950) on the sheet`s eastern margin and the sub-Kalahari geological map is therefore based on an interpretation of high-resolution airborne magnetic data controlled by the logs of about 92 boreholes. For the most part, the borehole information is from the percussion holes drilled for groundwater, with other boreholes drilled for kimberlites, or into the Molopo farms complex. Most of the boreholes occur in the southern half of the sheet, notably in the Molopo farms or around Malote where the Kalahari cover is relatively thin. Almost one-quarter of the boreholes intersected dolerite (including the majority of the boreholes targeted to intersect kimberlite). Most water boreholes penetrated into Waterberg sandstones or quartzites, with the remainder intersecting Karoo or Transvaal Supergroup strata.
