"sown yellow in winter/ its lights diminished come summer"
Passage of time. Emphasises the father has been coming here a long time - grief is an ongoing process with no resolution.
"the mossy gums of trench and rampart"
Harsh descriptions of the hill's structure. Nature has taken over, infused with construction. Represents cohesion between nature and man.
Y Gaer is a tribute to grief and the power of nature
"The land is three-sixty about you here/an answer to any question"
Complete encapsulation, nature provides comfort and security. Suggests walking through and viewing nature as a way to overcome/approach difficulty.
"Where he can lean full tilt/against the wind's shoulder"
Desire for support - uses nature as a crutch to cope with his son's passing - complete reliance on nature.
Personification - to reciprocate the father's need for comfort.
"only in bad weather"
Pathetic fallacy represents his grief, the storm represents his fury at his son's death.
"shout into the storm/finding at last/something huge enough to blame"
Cathartic - the wind would cover his shouts, relates to need to show a hard, masculine front in Welsh society. The elements provide a moment of respite.