Hertfordshire puddingstone
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Hertfordshire puddingstone is a conglomerate sedimentary rock composed of rounded flint pebbles cemented together by a younger matrix of silica quartz. The distinctive rock is largely confined to the
A fragment from a quern of probable Roman date made from Hertfordshire puddingstone. The rock contains many oval shaped grey and white pebbles of varying sizes in a quartz (silica) matrix.
A polished section of Hertfordshire puddingstone
Samples of Hertfordshire puddingstone at Hertford Museum
Hertfordshire puddingstone outside the Cock and Rabbit public house at The Lee, near Chesham
Silcrete
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Silcrete is an indurated soil duricrust formed when surface soil, sand, and gravel are cemented by dissolved silica. The formation of silcrete is similar to that of calcrete, formed by calcium carbona
Hertfordshire puddingstone
…around Chesham, where pieces can be seen as boundary stones and in rockeries. Despite a superficial similarity to concrete, it is an entirely natural silcrete. A fracture runs across both the pebbles and the sandy matrix as both have equal strength unlike concrete where the pebbles remain whole and a fracture…
Silcrete (siliceous paleosol) in the Waddens Cove Formation (formed during the Pennsylvanian), Sydney Basin, Nova Scotia
Bifacial silcrete point from Blombos Cave, South Africa, Middle Stone Age (71,000 BCE) (scale bar = 5cm)