from wikipedia:Laccoliths tend to form at relatively shallow depths and are typically formed by relatively viscous magmas, such as those that crystallize to diorite, granodiorite, and granite. Cooling underground takes place slowly, giving time for larger crystals to form in the cooling magma. The surface rock above laccoliths often erodes away completely, leaving the core mound of igneous rock.that would explain a lot of the weird granite formations we saw in the high veldt of Zimbabwe....Brittania on line has a link to that here
Although these large masses are generally supposed to provide the best sample of the deep lithosphere (the outer shell of the Earth), they often appear to be floored over most of their outcrop area. They usually occur as laccoliths (low domelike intrusions with a flat base found between sedimentary beds), lopoliths (laccoliths with basin-shaped bases), or sills (tabular intrusions between other rocks).and HERE.
Great Dyke, narrow series of long, low ridges and hills in Zimbabwe, trending for about 320 miles (515 km). Consisting of four igneous complexes, they increase in height northward to about 1,500 feet (460 m) above the plateau surface in the Umvukwe Range, west of Harare (formerly Salisbury), the Zimbabwean capital. Minerals found in the Great Dyke include gold, silver, chromium, platinum, and nickel. Mica, asbestos, and tin are also extracted, as are minerals useful in construction.
and laccolith is not to be confused with Lopolith, Batholith, or Hydrolaccolith.
headsup GGG forum at FR...