This article is about the river in northeast Wales. For the river in west Wales, see River Alun, Pembrokeshire. For the river in Romania, see Alun River.
The River Alyn crosses the carboniferouslimestone from Halkyn Mountain and north through the Loggerheads area before heading southeast, passing through Mold before reaching its confluence with the River Dee northeast of Wrexham.
Between Loggerheads and Rhydymwyn it runs through the Alyn Gorge, which is the site of the caves Ogof Hesp Alyn, Ogof Hen Ffynhonnau and Ogof Nadolig. It mainly runs across a limestone surface, creating potholes and underwater caves, into which the river flows through some of the summer, when water levels have decreased significantly. For parts of this stretch the river bed is dry for most of the year.
Flows in the River Alyn are significantly affected by mining, particularly the Milwr mine drainage tunnel which diverts a sizeable amount (23 million gallons of water per day.[1]) of the River Alyn out of its catchment and into the Dee estuary at Bagillt.[2]
^* Appleton, Peter (1989). "Limestones and Caves of North Wales". In Ford, Trevor D. (ed.). Limestones and Caves of Wales. Cambridge University Press. pp. 233–7. ISBN0-521-32438-6.
