This junction was north of Merryton station, (a new station dating from 2005).
Here the Mid Lanark Lines (Caledonian Railway) of 1905 met the older Lesmahagow Railway. The former was single track and the latter double track. The Mid Lanark line doubled before the junction.
There was a signal box, opened with the new line in 1905, on the south side of the junction with another building behind it.
Just to the west, and predating the junction, was Merryton Colliery on the north side of the line, with a different signal box.
The box closed in 1949, the two lines becoming single track lines running north to Ferniegair Junction. The route south to Dalserf was singled, its northbound line being lifted south of Merryton Junction.
The older line closed to passengers in 1951. It closed altogether in 1964. The Mid Lanark closed to passengers in 1965 and closed altogether in 1968.
After closure the trackbed remained intact and became steadily overgrown. It was cleared and track relaid for the Larkhall re-opening of 2005.