Hundreds of visitors came from far and wide to catch a glimpse of a 170-million-year-old seabed when it opened to the public for the first time.

Horn Park Quarry, near Beaminster, opened to the general public for the first time over the Bank Holiday, allowing people to see an abundance of ammonites, belemnites and marine gastropods lying fossilised exactly where they had drifted down all those years ago.

They found out what life must have been like in the warm, shallow lagoons of equatorial West Dorset in the Jurassic period. The scorching Bank Holiday weather gave an insight into what temperatures might have been in that period, and visitors were able to borrow goggles, gloves and hammers to extract fossils from pre-excavated rocks as souvenirs.

Various display boards explained local geology in general, the global importance of Horn Park Quarry, in particular, and there were notes about plant life on the site. Further activities ranged from examining various rock types under a magnifying glass to writing poetry inspired by history. Younger visitors crossed the seabed in search of missing letters, gathering information as they went.

Six-year-old Chloe and Joshua, five, were the youngest of three generations in their family group. Chloe said: “It was really good stepping on so many fossils in the hunt."

Joshua particularly enjoyed searching for fossils to take home from the big pile and says he loved getting the certificate for completing the hunt.

Holidaymaker Margaret Slater, 98, was the oldest visitor, having spotted the signs by the roadside while she and her family were on their way elsewhere. "What a lovely surprise," she said. "You're never too old to be amazed."

The open day was devised and implemented by volunteers at Beaminster Museum in collaboration with Natural England, which manages the site, and the Jurassic Coast Trust, which happily shares expertise about the rocks and fossils there.

Sam Scriven, programme manager for Heritage and Conservation for the Jurassic Coast Trust, said: "What a fantastic day. And what a pleasure to welcome so many interested people to England's smallest National Nature Reserve. I think everyone that visited agreed that Horn Park Quarry has a 'wow' factor, and that was helped along hugely by the work put in by the volunteers at Beaminster Museum."

Brian Earl, curator of Beaminster Museum, added: "The day was all about Horn Park Quarry, but I’m pleased that museum volunteers were able to contribute their own unique brand of energy and ingenuity. It was a particular joy to see so many local people having their eyes opened to this hidden jewel on their own doorstep."

Members of the public may still arrange private visits for themselves by emailing info.beaminstermuseum@gmail.com.