However, the stomach does have a few special rolls and flutters resulting in an undulation of the entire lower torso.
The strata must once have risen above the present surface, and in many cases may be found descending to the surface again with a contrary dip, the intervening portion of the undulation having been worn away.
North of the Congo basin and separated from it by a broad undulation of the surface is the basin of Lake Chad - a flat-shored, shallow lake filled principally by the Shari coming from the south-east.
Climatic agencies have smoothed and modified everything rugged or abrupt, until an impression of gentle undulation rather than of grandeur is suggested.
Who knows but if our instruments were delicate enough we might detect an undulation in the crust of the earth?