The Cape Government Railway (CGR) from Cape Town was opened to Matjesfontein (192 miles 66 chains. Altitude 2966 feet) on 1 February 1878. From Matjiesfontein [today’s spelling] the alignment followed the course of the Bobbejaan River eastwards. The next passing loop was Whitehill (199 miles 27 chains. Altitude 2715 feet).
The logical route for the extension northwards from Whitehill, was adjacent to the course of the river. However, about 5 kms east of Whitehill, the Bobbejaan River shaped like an inverted and elongated “S” cuts a deep poort through the north - south Mostertshoek ridge. [This poort is known as Rietfonteinpoort.] This terrain would have necessitated two costly bridges each of two to three spans. In addition to the difficult terrain of the poort, the situation was complicated by Dwyka tillite inclusions in the dolerite sill. These geological features would have demanded extensive blasting.
Consequently about 3 kms north of Whitehill the alignment swung south-east away from the dry river course to cross the Mostertshoek ridge about 3 kms south of Rietfonteinpoort. This route over the ridge involved shallow cut-and-fill construction on the southern side. Deeper cuttings were necessary on the northern side. However, the rock in this area was relatively soft being Dwyka mudshale. A passing loop was built where the alignment crested the ridge. It was named Mostertshoek (203 miles 18 chains. Altitude 2722 feet). From Mostertshoek the alignment followed the course of a twisting spruit to the north-east. The alignment, with 1:40 and 1:60 embankments and cuttings, dropped...
