Arguably Cnoc Mordáin is the best of the south Connemara summits, its petite grandeur surpassing even the rough topped Errisbeg. From the Galway to Carna road (R340) its steep SE facing slopes, some 4k long, look extremely impressive. The slopes are not so steep on the NW side, making the mountain a long scarp. The ridge is split into two parts by a col midway which drops to around 275m.
This part of south Connemara is granite country. The slightly pinkish granite of the ridge has been shaped by the passage of abrasive laden ice into roche moutonee. The rock is in long ridges similar to what you often see in the corduroy country of the Cahas or on Mount Gabriel, only the rock here is the much harder granite. Incidentally according to Wikipedia 'The term "roche moutonnée" comes from the French for "fleecy rock", a term for a French wig, despite its popular misinterpretation as "rock sheep."' Certainly if you were a student of geology you could do worse than this ridge for examples of glacial landforms. In fact the entire ridge looks like a giant roche moutonee.
For a quick baggers dash for the summit you could start from the unfenced road NE of the summit at around A (L8800 3920)
which looks straightforward though I didn't try it.
To take in the whole ridge and get a decent walk you can park at the end of the public road at Mordáin (L85936 35062)
at the SW end. Walk up the track approximately west until you are nearing the trees and can head for the summit ridge.
As you rise on the ridge the view expands dramatically, revealing Kilkieran Bay to the east with its flooded intricate landscape and south Connemara summits such as Errisbeg. Eventually the view of the Bens, the Turks, the Devil's Mother and even Mweelrea appear. Linkback: mountainviews.ie/summit/897/comment/3865/