Victorian aqueduct on Avon Group (Lower Limestone Shale) © Elizabeth Woodger
This black limestone contains abundant marine fossils (e.g., brachiopods and crinoids). It belongs to the Avon Group (Lower Limestone Shale), which is found near the East and West Twin brooks in Burrington Combe.
Rainfall enters these streams and sinks underground in places where the impermeable Avon Group mudstone meets dissolvable Carboniferous limestone. Water flows through the extensive limestone aquifer, creating spectacular caves, before re-emerging along the spring line. This Victorian aqueduct (completed in 1851) still carries spring water through its pipeline to a reservoir supplying local drinking water.
Image part of the ‘Menhir 2023’ collection by Elizabeth Woodger, through the Moments on Mendip project.