Contemporary igneous outbursts are extremely common in some of the ancient formations, and add, by their resistance to atmospheric erosion, to the extreme ruggedness of the scenery.
The unity and ruggedness of the highlands of Wales have proved sufficient to isolate the people from those of the rest of South Britain, and to preserve a purely Celtic race, still very largely of Celtic speech.
There is something arresting in that bold " I am the Man "; and the lyrical intensity, the religious depth and beauty of the whole, may well blind us to occasional ruggedness of metre and language, abrupt transitions from figure to figure and other alleged blemishes, some of which may not have seemed such to the poet's contemporaries (e.g.
In the mountains, ruggedness combines with thin and scattered soil to make these districts of small agricultural value.
Much of the ruggedness and beauty of the mountains is due to the erosive action of many alpine glaciers that once existed on the higher summits, and which have left behind their evidences in valleys and amphitheatres with towering walls, polished rock-expanses, glacial lakes and meadows and tumbling waterfalls.