Jeremy Laurance: Last goodbyes that keep our loved ones' memories alive

I had never seen human ash until Sunday morning, when my brother-in-law shook a small part of Grandma out of the green plastic urn into the lid and handed it to his sister, my wife. It was much grittier than I expected. My first thought, which I guiltily suppressed, was that it looked like the Growmore I scatter on the roses each spring. Then I thought: could there be a better one-word epitaph for grandparents?

My wife took a pinch between her fingers and tossed it daintily into the air. "I need to check which way the wind is blowing," she said. Satisfied, she swung the lid – but too vigorously and its contents rose into the air, leaving the rest of us to brush Grandma out of our hair.

Then there was Grandpa. We were standing in a magnificent spot overlooking the Mawddach estuary near Barmouth in North Wales, where the family used to take their holidays. Swirls of mist curled over the amber and emerald trees at the head of the valley, the light glittered on the sandbanks as the tide raced out and beyond them rose the dark bulk of Cadair Idris, its peak lost in the clouds.

We had wanted Grandma and Grandpa to have a good view, in their final resting place. Were we mad? It had taken the 10 of us (four members of the family couldn't make it) all weekend to select the spot. We had crossed Barmouth bridge, spotting salmon in the tidal water, climbed another hill beside a gorge and circled a lake, its burnished surface unruffled by a breath of wind.

After lengthy debate we settled on a spot off the beaten track, thick with pink and purple heather (which Grandma loved), by a natural stone seat, where, we felt, they would be undisturbed. All the grandchildren took turns to shake the urns, some sprinkling carefully, others swinging vigorously, all of us shouting encouragement, till all around the heather was coated with a thin layer of white dust.

It was a mix of Roald Dahl and JRR Tolkien. Earlier we had creased up with laughter at a notice displayed in Barmouth harbour: "Any person found dumping ash, dust, clinker ... will be prosecuted". As we emerged from the cars later – "Have you got the grandparents?" someone yelled – the youngest grandchild bore them in a rucksack on his back, as they had borne him nearly two decades ago.

We expend enormous effort preparing for new arrivals into the world, planning pregnancy and birth, hoping for a good experience and a safe delivery – but so little thinking about what makes a good exit.

Some (more distant) members of the family had wondered why we had gone to the trouble and expense of taking a party of 10 to a distant corner of the country – to dispose of two shovelfuls of ash. All of us who were there felt differently. We had celebrated the family Grandpa and Grandma had created – and answered the question where people go when they die. Into the hearts of those who remember them.