Heart of Wales Geopark

The rocks, fossils and people helping us understand this part of Wales.

The Heart of Wales Geopark, or Geoparc Calon Cymru, is a charitable project centred on the Builth–Llandrindod Inlier and the surrounding area. Its purpose is to help people understand the local geology and its connections with our landscape, wildlife and heritage. There is active research here, alongside the work of making that research accessible through walks, educational resources and opportunities to learn.

The word ‘inlier’ describes an area of older rock exposed at the surface, with younger rocks around it. Here, those older rocks belong to the Ordovician period. Around 460 million years ago, this part of what would become Wales was a marine environment, with volcanic islands rising from the sea.

That takes a little time to picture. The hills and valleys we recognise today came much later. The rocks preserve evidence of volcanic eruptions and of mud accumulating on an ancient seabed. Over the long history that followed, movements in the Earth’s crust folded and fractured them. Much later still, ice reshaped the landscape.

The area has long been known for its fossils, particularly trilobites: extinct sea animals with segmented bodies and hard outer coverings. The Geopark’s identification resources describe around sixty species from its Ordovician rocks. Some had remarkable spines; others had unusually large eyes. Even within this one group, there was a wonderful variety of life.

One discovery has given researchers an especially detailed view of that ancient sea. At Castle Bank, near Llandrindod Wells, Dr Joe Botting and Dr Lucy Muir discovered fossils whose study, with colleagues from Amgueddfa Cymru and other institutions, was published in 2023. More than 170 species were reported, including sponges, worms, starfish and many other small animals.

Many of these creatures were only one to five millimetres long. What makes the site particularly important is the preservation of soft tissues, which usually decay without leaving much trace. Shells and other hard parts tell us a great deal, but here researchers can also study animals that would ordinarily be missing from the fossil record. Some specimens preserve extraordinarily fine details, including eyes, tentacles and traces of internal organs.

I find the scale of this work very absorbing. Such small remains, examined patiently, can change our understanding of life hundreds of millions of years ago. Much remains to be discovered and understood.

The geology also helps us look more carefully at the differences between familiar places. Aberedw Hill, for example, includes Silurian mudstones, younger than the Ordovician rocks at the centre of the Geopark. Those hills belong to different chapters of the region’s history. Learning that makes me want to pay closer attention to the ground as well as the view.

The mineral springs at Llandrindod Wells and Builth Wells are another connection between geology and local life. Their waters move through fractured rock, and their mineral content reflects that underground journey. These springs are part of the area’s spa heritage. To me, they are a particularly clear example of how the ground beneath a place can influence its human history.

The Geopark’s interest in biodiversity matters too. It encourages us to consider the relationships between the rocks, the landscape and the life it supports. I would like to learn more about how the geology here influences soils and the movement of water, and how those conditions help shape the habitats we know on the farm and beyond.

For anyone staying at Fforest Fields, a visit to Radnorshire Museum in Llandrindod Wells offers a useful place to begin. Its collections include geology, fossils and natural history. The Geopark’s own resources and guided activities offer ways to take that interest out into the landscape.

You do not need to arrive knowing the names of the rocks. A little curiosity is enough to begin. I like the thought of returning to a familiar walk with one new thing to look for, and gradually getting to know this part of Wales more closely.

Find out more through the Heart of Wales Geopark website and Facebook page.