THE QUIZZYHOTA LACCOLITE 73 
at first sight it would appear that the actual base of the laccolite 
was exposed, but farther down stream the dolerite descends to the 
bed of the river. The sedimentary rocks in the bed of the river, 
though quite close to the dolerite, are unaltered and undisturbed. 
The top of the laccolite spreads out to the south beneath the 
thin covering of sedimentary beds, perhaps reaching the village of 
Komgha which lies to the west-southwest about 1o miles from the 
bridge in a straight line (18 by railway). Three miles from the 
village, however, the railway skirts a shallow valley on the plateau 
which is covered with rich black soil, very different from the light 
sandy soil derived from the weathering of the sedimentary beds, 
which is good only for pasture lands; here, however, every inch is 
cultivated. This is the first exposure of dolerite which one can 
definitely connect with the Quizzyhota laccolite. The dolerite 
continues along the railway for 2 miles, then runs over the sedi- 
mentary covering for half a mile, and then again for about 200 
yards is carried over the dolerite. Beyond, the railway cuttings 
are in the sedimentary beds forming a thin undisturbed covering 
to the laccolite, till the Etanga Valley is reached 2 miles farther on. 
Here the railway crosses the road at No. 6 railway cottage, and the 
plunge into the valley of the Kei begins. For a little distance the 
railway is cut in the eastern slope of the laccolite, which is here 
intensely weathered, the square jointed blocks having broken down 
into a brown sand, while in their centers there remain, in many cases, 
rounded blocks of quite unaltered rock. The blocks exposed in a 
similar position on the western end facing the river are jointed in 
the same way, but there is no evidence of the spheroidal weathering 
nor of the intense alteration. It appears that the intense crumbling 
is a consequence of the covering of sour soil which yields organic 
acids in large quantities and thus supplies a powerful solvent for the 
iron combined in the ferro-magnesian minerals. The finest example 
of the spheroidal weathering about here is in the great laccolite 
which lies 3 miles from Amabele Junction and which is exposed 
along the railway to within a few miles of Komgha village (27 miles 
from Amabele). Here the jointing is horizontal and vertical and 
every tenth block, more or less, has a solid unaltered core of grey 
dolerite. The weathered material can be dug with a spade and is 
