Read the rocks: Mamley stromatolite trail

Stromatolites form when sticky mats of microbes trap fine sediment, grow upward through it, and trap more, layer by layer, over centuries. Cut through, they show wavy bands, domes and little columns. At Mamley these structures are preserved in pale dolomite laid down in a shallow Proterozoic sea.

From the Rock Garden, drive or walk the few minutes up to the Mamley site. Look along the exposed rock faces for repeating curved layers, a few millimetres thick, stacked into mounds. Wet rock shows the pattern more clearly, so a damp morning can help; a phone torch held at a low angle brings out the relief.

The site is protected as a National Geological Monument. Look, photograph and touch gently, but do not hammer, chip or remove anything. We give children a simple checklist: find a dome, a column and a flat layer. It turns a five-minute glance into half an hour of looking.