ABSTRACT
The Great Rift Valley is one of the remarkable features and extends for several hundred miles. Apparently it is due to an immense subsidence or ‘down-throw.’ It has several extinct volcanoes along its floor, and many lakes, most of which are salt. The bridges are of three types as regards piers and abutments — first, masonry piers and abutments; second, piers and abutments of concrete; and, lastly, trestle piers, composed of 3-foot diameter steel cylinders, braced together with cross girders and angle iron, the cylinders being filled with concrete. Small drains are provided for by stoneware pipes, 12 inches and 18 inches diameter, laid on a concrete bed; larger drains are of oval steel cylinders on concrete, while arched culverts from 3-foot to 15-foot spans are usually of concrete. Along the floor of the Rift Valley itself, which is crossed / very obliquely, the works are of a simple character, only two streams of any magnitude being met with.
