Mount Kilimanjaro began forming in Africa's Great Rift Valley around a million years ago. George Solt, from Buckinghamshire, has not been around for quite as long as that, but at the age of 82, he has become the oldest man to climb the world's largest free-standing mountain.
Mr Solt took on the challenge with his son, daughter-in-law and three grandchildren, one of whom is 12 years old, in memory of his wife, Jen, who died last year. The money he raised by doing the climb will go towards Willen Hospice in Milton Keynes, where his wife spent her final days. "It's great, I can say I'm a world record holder and have done something no one else has ever done," Mr Solt said.
It took the group six days to get up and two days to get down Kilimanjaro. Mr Solt had prepared for months, using weights, cycling hard and walking. The hardest part about the challenge, he said, were the "headaches, nausea and plain tiredness". When he reached the top of the 5,895m peak, Mr Solt said, he was "totally blank and exhausted. I was just glad to be able to turn around and get down again".
But it was then that he encountered the most difficulty. He said the descent was "absolutely awful, I was absolutely wrecked. The bottom half was the worst, in the wet rainforest, it was very slippery, the next day I couldn't even walk down the hotel steps".
His 52-year-old son didn't make it to the summit: "He just suddenly went absolutely bananas and had to be taken down and was extremely ill on the way down but right as rain the minute he got to the bottom."
Mrs Solt had been a keen climber too, mountaineering until she was 80, but suffered from altitude sickness, which meant the couple did most of their climbing in Europe, rather than on higher peaks such as Everest.
Mr Solt is five years younger than the Frenchman Valtée Daniel who, at 87, claims to be the oldest man to have climbed the mountain. But Mr Daniel's climb has never been recognised by the Guinness Book of Records, who insist on certain rules being followed in order for a climber's claim to be accepted. In particular, the record attempt has to be verified by independent witnesses, must be filmed and photographed as well as meticulously documented in a logbook.
Mr Solt reached Kilimanjaro's Uhuru peak on 14 July 2010, and is now resting at home, waiting for Guinness World Records to verify his climb.