The diagram below shows a summary of depositional and tectonic events affecting the Glasgow area from the end of the Devonian through the Carboniferous and into the early Permian.
The rocks of the Fossil Grove are part of the Limestone Coal Formation (LC) which is about 325 million years old. The dolorite sill is of Early Permian age (about 294 million years)
LL = Lower Limestone Formation, LC = Limestone Coal Formation, UL = Upper Limestone Formation.