Not sure how best to describe these, but assuming you're on a train from Porthmadog travelling towards Blaenau along the old route now flooded! As you come out of the tunnel you pass the site of Moelwyn Halt, there was a small village here believe it or not of mainly railway workers and quarrymen.
To the right, a branch ran to the Brookes' Granite Quarry which can still be seen south of the lake.
To the left (North) a branch ran to the Moelwyn Zinc Mine, which later produced Copper and then Slate.
A little further on, again to the North was another branch which served the Moelwyn Slate Quarry. This has 4 (I think) inclines which are obvious today and are probably the ones that LAP was referring to behind the power station.
Next comes the Wrysgan Quarry Incline followed by Tanygrisiau Station. Cwmorthin Incline came down to the line just beyond the station site and was always troublesome to the railway company.
As you can see, the line had branches coming down to it all over the place - 5 there in just over a mile! I must get round to scanning a map in to show this clearer!